Tunable Magnetic Transition to a Singlet Ground State in a 2D van der Waals Layered Trimerized Kagomé Magnet

Incorporating magnetism into two-dimensional (2D) van der Waals (vdW) heterostructures is crucial for the development of functional electronic and magnetic devices. Here, we show that Nb₃X₈ (X = Cl, Br) is a family of 2D layered trimerized kagomé magnets that are paramagnetic at high temperatures and undergo a first-order phase transition on cooling to a singlet magnetic state. X-ray diffraction shows that a rearrangement of the vdW stacking accompanies the magnetic transition, with high- and low-temperature phases consistent with scanning transmission electron microscopy images of the end members α-Nb₃Cl₈ and β-Nb₃Br₈. The temperature of this transition is systematically varied across the solid solution Nb₃Cl_8-xBr_x (x = 0-8), with x = 6 having transitions near room temperature. The solid solution also varies the optical properties, which are further modulated by the phase transition. As such, they provide a platform on which to understand and exploit the interplay between dimensionality, magnetism, and optoelectronic behavior in vdW materials.

Effects of Solidification Pressure and Heat Treatment on the Microstructure and Micro-Hardness of AlSi9CuMg Alloy

The effect of high pressure (135 MPa) and the following heat treatment on the microstructure and micro-hardness of the squeezing cast AlSi9CuMg alloy is investigated, using optical microscopy (OM), Vickers tester, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results indicate that the application of high pressure can increase under-cooling and the cooling rate during solidification and cause the refinement of the microstructure. The enhanced melt flow resulting from high pressure can also break the dendrite to form the spherical and elliptical primary α (Al) grains during the early stage of solidification. The winter-sweet flower-shaped primary α (Al) phases can also be formed through plastic deformation caused by the flow of the partially solidified melt. The ageing treatment results showed that a maximum (peak) micro-hardness value was obtained for each of the three ageing temperatures at different ageing times, and the highest peak value was achieved at 175 °C for 480 min. The micro-hardness change of the sample under different ageing processes was attributed to the variation of type, density, and size of the precipitates.

nH2O) and their stability under conditions of variable temperature

Mineral phases which can be thought of as members of a metatorbernite-metazeunerite solid solution (Cu(UO₂)₂(PO₄)_{2- x}(AsO₄) _x.8H₂O have been identified in radioactive samples from spoil heaps at the uranium mine site in South Terras, Cornwall (grid reference SW935523). A complete solid solution (0 <  x < 2) was synthesized by precipitation from solution using uranium (VI) nitrate and copper (II) chloride and phosphoric acid/arsenic acid in the appropriate molar proportions. Refined unit cell parameters determined by Pawley fitting of powder X-ray diffraction data showed a linear variation in the a unit cell parameter according to Vegard's Law, allowing the composition of the natural mineral phases found at South Terras to be determined from measurement of their unit cell parameters. High-resolution variable-temperature synchrotron powder X-ray diffraction studies were carried out at the Diamond Light Source on three members of this solid solution ( x = 0, 1, 2) and showed different structural behaviour as a function of composition and temperature. Metatorbenite ( x = 0) retains its tetragonal symmetry at low temperatures and dehydrates to an amorphous phase at 473 K, whereas metazeunrite ( x = 2) transforms to an orthorhombic phase at low temperatures, regains its tetragonal symmetry on heating to 323 K and undergoes a further transition to an, as yet, unidentified phase at 473 K. This article is part of the theme issue 'Fifty years of synchrotron science: achievements and opportunities'.

Organic-mineral interfacial chemistry drives heterogeneous nucleation of Sr-rich (Ba x , Sr1-x )SO4 from undersaturated solution

Sr-bearing marine barite [(Ba _x , Sr_1-x )SO₄] cycling has been widely used to reconstruct geochemical evolutions of paleoenvironments. However, an understanding of barite precipitation in the ocean, which is globally undersaturated with respect to barite, is missing. Moreover, the reason for the occurrence of higher Sr content in marine barites than expected for classical crystal growth processes remains unknown. Field data analyses suggested that organic molecules may regulate the formation and composition of marine barites; however, the specific organic-mineral interactions are unclear. Using in situ grazing incidence small-angle X-ray scattering (GISAXS), size and total volume evolutions of barite precipitates on organic films were characterized. The results show that barite forms on organic films from undersaturated solutions. Moreover, from a single supersaturated solution with respect to barite, Sr-rich barite nanoparticles formed on organics, while micrometer-size Sr-poor barites formed in bulk solutions. Ion adsorption experiments showed that organic films can enrich cation concentrations in the adjacent solution, thus increasing the local supersaturation and promoting barite nucleation on organic films, even when the bulk solution was undersaturated. The Sr enrichment in barites formed on organic films was found to be controlled by solid-solution nucleation rates; instead, the Sr-poor barite formation in bulk solution was found to be controlled by solid-solution growth rates. This study provides a mechanistic explanation for Sr-rich marine barite formation and offers insights for understanding and controlling the compositions of solid solutions by separately tuning their nucleation and growth rates via the unique chemistry of solution-organic interfaces.

Structure, Shift in Redox Potential and Li-Ion Diffusion Behavior in Favorite LiFe1⁻xVxPO4F Solid-Solution Cathodes

Solid-solution Li-ion cathode materials transform through a single-phase reaction thus leading to a long-term structural stability and improved cyclability. In this work, a two- to single-phase Li⁺-extraction/insertion mechanism is studied through tuning the stoichiometry of transition-metal Fe/V cations to trigger a transition in the chemical reactivity path. Tavorite triclinic-structured LiFe_1−xV_xPO₄F (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1) solid-solution powders were prepared by a facile one-step solid-state method from hydrothermal-synthesized and commercial raw materials. The broad shape of cyclic voltammetry (CV) peaks, sloping charge/discharge profiles and sloping open-circuit voltage (OCV) profiles were observed in LiFe_1−xV_xPO₄F solid-solution cathodes while 0 < x < 1. These confirm strongly a single-phase behavior which is different from the two-phase behavior in the end-members (x = 0 or 1). The electronegativity of M (M = Fe_1−xV_x) for the redox potential of Fe^2+/3+ couple or the M–O₄F₂ bond length for the V^3+/4+ couple plays respectively a dominant role in LiFe_1−xV_xPO₄F solid-solution cathodes.

The Enhancement of H2 Evolution over Sr1-1.5xTbxWO4 Solid Solution under Ultraviolet Light Irradiation

In this work, Sr_1-1.5xTb_xWO₄ (0 ≤ x ≤ 0.2) solid solutions were synthesized via a traditional high-temperature solid state method. Le Bail fitting on the powder X-ray diffraction (XRD) pattern showed that these solid solutions are pure phase. Scanning electron microscopy showed that the SrWO₄ and Sr_0.82Tb_0.12WO₄ samples are composed of micrometer particles and submicron crystallites, respectively. Ultraviolet-visible diffuse reflectance spectra suggested that the bandgaps of Sr_1-1.5xTb_xWO₄ are narrower than the undoped sample. The Sr_0.82Tb_0.12WO₄ sample, with the assistance of 1.5 wt % Ru-cocatalyst, exhibits the best performance for H₂ evolution in 5 vol % aqueous triethanolamine (TEOA), which results in about 6.1 and 2.8 times efficiency improvement compared with the intrinsic SrWO₄ in methanol and aqueous TEOA, respectively. All the photocatalysts recycled after the photocatalytic reactions showed no degradation when checked by powder XRD.

Combustion Synthesis of Non-Precious CuO-CeO₂ Nanocrystalline Catalysts with Enhanced Catalytic Activity for Methane Oxidation

In this study, xCuO-CeO₂ mixed oxide catalysts (Cu weight ratio x = 1.5, 3, 4.5, 6 and 15 wt.%) were prepared using solution combustion synthesis (SCS) and their catalytic activities towards the methane (CH₄) oxidation reaction were studied. The combustion synthesis of the pure CeO₂ and the CuO-CeO₂ solid solution catalysts was performed using copper and/or cerium nitrate salt as an oxidizer and citric acid as a fuel. A variety of standard techniques, including scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were employed to reveal the microstructural, crystal, thermal and electronic properties that may affect the performance of CH₄ oxidation. The CuO subphase was detected in the prepared solid solution and confirmed with XRD and Raman spectroscopy, as indicated by the XRD peaks at diffraction angles of 35.3° and 38.5° and the Ag Raman mode at 289 cm-1, which are characteristics of tenorite CuO. A profound influence of Cu content was evident, not only affecting the structural and electronic properties of the catalysts, but also the performance of catalysts in the CH₄ oxidation. The presence of Cu in the CeO₂ lattice obviously promoted its catalytic activity for CH₄ catalytic oxidation. Among the prepared catalysts, the 6% CuO-CeO₂ catalyst demonstrated the highest performance, with T50 = 502 °C and T80 = 556 °C, an activity that is associated with the availability of a fine porous structure and the enhanced surface area of this catalyst. The results demonstrate that nanocrystalline copper-ceria mixed oxide catalysts could serve as an inexpensive and active material for CH₄ combustion.

Effects of an Alternating Magnetic Field/Ag Multi-Alloying Combined Solidification Process on Cu⁻14Fe Alloy

An alternating magnetic field (AMF)/Ag multi-alloying combined process was applied to the solidification of Cu–14Fe alloy to study its effects on the microstructure and properties of the resulting samples. The applied AMF and Ag multi-alloying had positive effects on the refinement of the primary Fe phase and precipitation of Fe solute atoms, respectively. These results indicated that the combined AMF/Ag multi-alloying process was effective to improve the distribution of the primary Fe phase and reduce the Fe content of the Cu matrix, which increased the conductivity of the alloy. The application of the combined AMF/Ag multi-alloying process to the solidification of Cu–Fe alloy provided samples with improved comprehensive properties compared with those of samples solidified using a single process (AMF or Ag multi-alloying).

A new form of Cd3TeO6 revealing dimorphism

Phase-formation studies in the system CdO-TeO3 using a CsCl/NaCl melt at comparatively low temperatures revealed that tricadmium orthotellurate(VI), Cd3TeO6, is dimorphic. The new modification of Cd3TeO6 is denoted as the β-form and adopts the rhombohedral Mg3TeO6 structure type with one Cd and two O sites in general positions, and two Te sites with site symmetry each. In comparison with the previously reported monoclinic cryolite-type α-form that was prepared at higher temperatures, β-Cd3TeO6 has a much lower density and most likely represents a metastable modification. Whereas the [TeO6] octa-hedra in both polymorphs are very similar and show only minor deviations from ideal values, the polyhedra around the CdII sites are different, with a distorted [CdO6] octa-hedron in both modifications but an additional [CdO8] polyhedron with a [4 + 4] coordination in the α-form.

A Study of the Effect of 2 at.% Sn on the Microstructure and Isothermal Oxidation at 800 and 1200 °C of Nb-24Ti-18Si-Based Alloys with Al and/or Cr Additions

Alloying with Al, Cr, Sn, and Ti significantly improves the oxidation of Nb silicide-based alloys at intermediate and high temperatures. There is no agreement about what the concentration of Sn in the alloys should be. It has been suggested that with Sn ≤ 3 at.% the oxidation is improved and formation of the brittle A15-Nb₃Sn compound is suppressed. Definite improvements in oxidation behaviour have been observed with 5 at.% Sn or even higher concentrations, up to 8 at.% Sn. The research reported in this paper is about three model alloys with low Sn concentration and nominal compositions Nb-24Ti-18Si-5Cr-2Sn (ZX3), Nb-24Ti-18Si-5Al-2Sn (ZX5), and Nb-24Ti-18Si-5Al-5Cr-2Sn (ZX7) that were studied to understand the effect of the 2 at.% Sn addition on as-cast and heat-treated microstructures and isothermal oxidation in air at 800 and 1200 °C for 100 h. There was macrosegregation of Si and Ti in the alloys ZX3 and ZX5 and only of Si in the alloy ZX7. The Nb_ss was stable in all alloys. Tin and Ti exhibited opposite partitioning behaviour in the Nb_ss. The βNb₅Si₃ was the primary phase in all three cast alloys and had partially transformed to αNb₅Si₃ in the alloy ZX3. Aluminium in synergy with Sn increased the sluggishness of the βNb₅Si₃ to αNb₅Si₃ transformation during solidification. After the heat treatment the transformation of βNb₅Si₃ to αNb₅Si₃ had been completed in all three alloys. Fine precipitates were observed inside some αNb₅Si₃ grains in the alloys ZX5 and ZX7. In the latter alloys the A15-Nb₃X (X = Al, Si, and Sn) formed after the heat treatment, i.e., the synergy of Al and Sn promoted the stability of A15-Nb₃X intermetallic in these Nb-silicide-based alloys even at this low Sn concentration. A Nb_ss + Nb₅Si₃ eutectic formed in all three alloys and there was evidence of anomalous eutectic in the parts of the alloys ZX3 and ZX7 that had solidified under high cooling rate and/or high melt undercooling. A very fine ternary Nb_ss + Nb₅Si₃ + NbCr₂ eutectic was also observed in parts of the alloy ZX3 that had solidified under high cooling rate. At 800 °C none of the alloys suffered from catastrophic pest oxidation; ZX7 had a smaller oxidation rate constant. A thin Sn-rich layer formed continuously between the scale and Nb_ss in the alloys ZX3 and ZX5. At 1200 °C the scales formed on all three alloys spalled off, the alloys exhibited parabolic oxidation in the early stages followed by linear oxidation; the alloy ZX5 gave the smallest rate constant values. A thicker continuous Sn-rich zone formed between the scale and substrate in all three alloys. This Sn-rich zone was noticeably thicker near the corners of the specimen of the alloy ZX7 and continuous around the whole specimen. The Nb₃Sn, Nb₅Sn₂Si, and NbSn₂ compounds were observed in the Sn-rich zone. At both temperatures the scales formed on all three alloys consisted of Nb-rich and Nb and Si-rich oxides, and Ti-rich oxide also was formed in the scales of the alloys ZX3 and ZX7 at 1200 °C. The formation of a Sn-rich layer/zone did not prevent the contamination of the bulk of the specimens by oxygen, as both Nb_ss and Nb₅Si₃ were contaminated by oxygen, the former more severely than the latter.

A Study of the Effects of Al, Cr, Hf, and Ti Additions on the Microstructure and Oxidation of Nb-24Ti-18Si Silicide Based Alloys

In Nb-silicide based alloys Al, Cr, Hf, and Ti additions are crucial for achieving balance of properties. It is not known how the simultaneous addition of Hf with Al and Ti, or Hf with Al, Cr, and Ti affects macrosegregation, and how the alloying affects hardness, Young’s modulus and bulk alloy oxidation, and contamination of the solid solution Nb_ss and the Nb₅Si₃ compound by oxygen. Two alloys with nominal compositions (at.%) Nb-24Ti-18Si-5Al-5Hf (alloy NbSiTiHf-5Al) and Nb-24Ti-18Si-5Al-5Cr-5Hf (alloy NbSiTiHf-5Al-5Cr) were studied in the as-cast and heat-treated conditions and after isothermal oxidation at 800 and 1200 °C and were compared with similar alloys without Hf. In both alloys there was macrosegregation of Si and Ti, which was more severe in NbSiTiHf-5Al. Both alloys formed Nb_ss+βNb₅Si₃ eutectic. The Nb_ss was stable and its Al and Cr concentrations increased with increasing Ti concentration. In both conditions the βNb₅Si₃ was observed in the alloys NbSiTiHf-5Al and NbSiTiHf-5Al-5Cr, and the γNb₅Si₃ only in the alloy NbSiTiHf-5Al. In both heat-treated alloys, separate Hf-rich Nb₅Si₃ grains were formed. The Si and Al concentrations in Nb₅Si₃ respectively decreased and increased with increasing Ti concentration. Al and Cr had a stronger hardening effect in the Nb_ss than Al, Cr, and Hf. Al, Cr, and Ti had a stronger negative effect on the Young’s modulus of the Nb_ss compared with Al, Cr, Hf, and Ti. When Nb was substituted by Ti, Cr, and Hf, and Si by Al in the βNb₅Si₃, the Young’s modulus was reduced compared with the unalloyed silicide. At 800 °C both alloys did not exhibit catastrophic pest-oxidation after 100 h. The Nb_ss and Nb₅Si₃ were contaminated by oxygen in both alloys, the former more severely. At 1200 °C the scales spalled-off, more severely in the alloy NbSiTiHf-5Al, where substrate that was heavily contaminated by oxygen below the scale also spalled-off. In both alloys the contamination of Nb₅Si₃ and Nb_ss by oxygen was more severe compared with 800 °C, but the silicides were not contaminated by oxygen in their bulk. The Nb_ss was not contaminated by oxygen only in the bulk of the alloy NbSiTiHf-5Al-5Cr.

Polymorphic phase transformations of 3-chloro-trans-cinnamic acid and its solid solution with 3-bromo-trans-cinnamic acid

We have investigated the polymorphic phase transformations above ambient temperature for 3-chloro-trans-cinnamic acid (3-ClCA, C₉H₇ClO₂) and a solid solution of 3-ClCA and 3-bromo-trans-cinnamic acid (3-BrCA, C₉H₇BrO₂). At 413 K, the γ polymorph of 3-ClCA transforms to the β polymorph. Interestingly, the structure of the β polymorph of 3-ClCA obtained in this transformation is different from the structure of the β polymorph of 3-BrCA obtained in the corresponding polymorphic transformation from the γ polymorph of 3-BrCA, even though the γ polymorphs of 3-ClCA and 3-BrCA are isostructural. We also report a high-temperature phase transformation from a γ-type structure to a β-type structure for a solid solution of 3-ClCA and 3-BrCA (with a molar ratio close to 1:1). The γ polymorph of the solid solution is isostructural with the γ polymorphs of pure 3-ClCA and pure 3-BrCA, while the β-type structure produced in the phase transformation is structurally similar to the β polymorph of pure 3-BrCA.

Controlling Thermal Expansion Behaviors of Fence-Like Metal-Organic Frameworks by Varying/Mixing Metal Ions

Solvothermal reactions of 3-(4-pyridyl)-benzoic acid (Hpba) with a series of transition metal ions yielded isostructral metal-organic frameworks [M(pba)2]·2DMA (MCF-52; M = Ni2+, Co2+, Zn2+, Cd2+, or mixed Zn2+/Cd2+; DMA = N,N-dimethylacetamide) possessing two-dimensional fence-like coordination networks based on mononuclear 4-connected metal nodes and 2-connected organic ligands. Variable-temperature single-crystal X-ray diffraction studies of these materials revealed huge positive and negative thermal expansions with |α| > 150 × 10-6 K-1, in which the larger metal ions give the larger thermal expansion coefficients, because the increased space not only enhance the ligand vibrational motion and hinged-fence effect, but also allow larger changes of steric hindrance between the layers. In addition, the solid-solution crystal with mixed metal ions further validates the abundant thermal expansion mechanisms of these metal-organic layers.

Synthesis and Electrochemistry of O3-type NaFeO2-NaCo0.5Ni0.5O2 Solid Solutions for Na-Ion Positive Electrodes

The synthesis, structure, and electrochemistry in Na cells of NaFe _xM_{1- x}O₂ positive electrode materials with M = Ni, Co_0.5Ni_0.5, and Co are reported. In particular, the properties of O3-NaFeO₂-NaCo_0.5Ni_0.5O₂ solid solutions having compositions NaFe _x(Co_0.5Ni_0.5)_{1- x}O₂ with 0 ≤ x ≤ 0.5 are explored. It is found that the substitution of Fe in NaNi_0.5Co_0.5O₂ causes an increase in first cycle energy density from 320 to 440 mWh/g in a 1.5-4.0 V test. However, capacity retention is generally reduced when x is increased for all M = Ni, Co_0.5Ni_0.5, and Co. In general, NaFe _xM_{1- x}O₂ samples with M = Co had the highest capacity retention for all values of x. Ex situ X-ray diffraction and Mössbauer results of as-prepared and charged materials are directly compared for NaFe _x(Co_0.5Ni_0.5)_{1- x}O₂ and NaFe _xCo_{1- x}O₂ ( x = 0.4, 0.5). Iron was found to be in the +3 oxidation state in the as-prepared materials. A significant fraction of Fe³⁺ is oxidized to Fe⁴⁺ in these samples when they are charged to 4.0 V.

Ge0.57Ti0.43O2: a new high-pressure material with rutile-type crystal structure

Single crystals of a GeO2-TiO2 solid solution with the corresponding composition Ge0.57Ti0.43O2 (germanium titanium tetra-oxide) were obtained by devitrification of germania-titania glass at high pressure and temperature. The new compound crystallizes in the rutile structure type (space group P42/mnm), where Ge and Ti share the same position M (site symmetry m.mm), with occupancy values of 0.57 (3) and 0.43 (3), respectively, and one O-atom position (m.2m). The M site is in a sixfold O-atom coordination and, as in the original TiO2 rutile structure, an elongation of the O-M-O bonds along the c-axis direction of the coordination polyhedron and deviation of the angles from 90° lead to a decrease in the coordination symmetry from octa-hedral to tetra-gonal. The Ge and Ti atoms are fully disordered in the structure, which indicates that the rutile structure is surprisingly pliant given the differing sizes of the two cations.

Crystal Structure and Thermoelectric Properties of Lightly Substituted Higher Manganese Silicides

The dissipation of MnSi layered precipitates during solidification is critical for further enhancement of the thermoelectric properties of the higher manganese silicides. We have investigated the effects of partial substitution of V in Mn sites and of Ge in Si sites on the crystal structures and thermoelectric properties of these silicides in detail. As previously reported, a small amount of V-substitution is quite effective in completely dissipating the MnSi striations; in contrast, a small proportion of these MnSi striations always remains present in the Ge-substitution case, even in the vicinity of the Ge solubility limits. For completely MnSi-dissipated samples, domain separation of the regular and highly strained arrangements of the Si atoms is realized. This domain separation suppresses the deterioration of the carrier mobility of the partially V-substituted samples and maintains even higher electrical conductivity to yield a high thermoelectric power factor of ∼2.3 mW/K 2 m at higher temperatures.

Alloying and Hardness of Eutectics with Nbss and Nb₅Si₃ in Nb-silicide Based Alloys

In Nb-silicide based alloys, eutectics can form that contain the Nb_ss and Nb₅Si₃ phases. The Nb₅Si₃ can be rich or poor in Ti, the Nb can be substituted with other transition and refractory metals, and the Si can be substituted with simple metal and metalloid elements. For the production of directionally solidified in situ composites of multi-element Nb-silicide based alloys, data about eutectics with Nb_ss and Nb₅Si₃ is essential. In this paper, the alloying behaviour of eutectics observed in Nb-silicide based alloys was studied using the parameters ΔH_mix, ΔS_mix, VEC (valence electron concentration), δ (related to atomic size), Δχ (related to electronegativity), and Ω (= T_m ΔS_mix/|ΔH_mix|). The values of these parameters were in the ranges −41.9 < ΔH_mix <−25.5 kJ/mol, 4.7 < ΔS_mix < 15 J/molK, 4.33 < VEC < 4.89, 6.23 < δ < 9.44, 0.38 < Ω < 1.35, and 0.118 < Δχ < 0.248, with a gap in Δχ values between 0.164 and 0.181. Correlations between ΔS_mix, Ω, ΔS_mix, and VEC were found for all of the eutectics. The correlation between ΔH_mix and δ for the eutectics was the same as that of the Nb_ss, with more negative ΔH_mix for the former. The δ versus Δχ map separated the Ti-rich eutectics from the Ti-poor eutectics, with a gap in Δχ values between 0.164 and 0.181, which is within the Δχ gap of the Nb_ss. Eutectics were separated according to alloying additions in the Δχ versus VEC, Δχ versus <Si>, δ versus <Si>, and VEC versus <Si> maps, where <Si> = Al + Ge + Si + Sn. Convergence of data in maps occurred at δ ≈ 9.25, VEC ≈ 4.35, Δχ in the range ≈ 0.155 to 0.162, and <Si> in the range ≈ 21.6 at.% to ≈ 24.3 at.%. The convergence of data also indicated that the minimum concentration of Ti and maximum concentrations of Al and Si in the eutectic were about 8.7 at.% Ti, 6.3 at.% Al, and 21.6 at.% Si, respectively, and that the minimum concentration of Si in the eutectic was in the range 8 < Si < 10 at.%.

In Situ Embedded Pseudo Pd-Sn Solid Solution in Micropores Silica with Remarkable Catalytic Performance for CO and Propane Oxidation

Most of the industrial and environmental catalytic reactions are operated at high temperature for a long time, and the sintering of the active centers is the main factor leading to catalysts deactivation, especially for noble metal catalysts. Herein we develop a dual confinement (enhanced metal-oxide interaction and the porous shell confinement) strategy to prepare Pd-Sn pseudo solid solution and in situ embedded in microporous silica for the first time and showed superior catalytic performance for CO and propane total oxidation (two main vehicle emission gases), even stored more than 640 days.

A New Class of Ternary Compound for Lithium-Ion Battery: from Composite to Solid Solution

Searching for high-performance cathode materials is a crucial task to develop advanced lithium-ion batteries (LIBs) with high-energy densities for electrical vehicles (EVs). As a promising lithium-rich material, Li₂MnO₃ delivers high capacity over 200 mAh g^-1 but suffers from poor structural stability and electronic conductivity. Replacing Mn⁴⁺ ions by relatively larger Sn⁴⁺ ions is regarded as a possible strategy to improve structural stability and thus cycling performance of Li₂MnO₃ material. However, large difference in ionic radii of Mn⁴⁺ and Sn⁴⁺ ions leads to phase separation of Li₂MnO₃ and Li₂SnO₃ during high-temperature synthesis. To prepare solid-solution phase of Li₂MnO₃-Li₂SnO₃, a buffer agent of Ru⁴⁺, whose ionic radius is in between that of Mn⁴⁺ and Sn⁴⁺ ions, is introduced to assist the formation of a single solid-solution phase. The results show that the Li₂RuO₃-Li₂MnO₃-Li₂SnO₃ ternary system evolves from mixed composite phases into a single solid-solution phase with increasing Ru content. Meanwhile, discharge capacity of this ternary system shows significantly increase at the transformation point which is ascribed to the improvement of Li⁺/e^- transportation kinetics and anionic redox chemistry for solid-solution phase. The role of Mn/Sn molar ratio of Li₂RuO₃-Li₂MnO₃-Li₂SnO₃ ternary system has also been studied. It is revealed that higher Sn content benefits cycling stability of the system because Sn⁴⁺ ions with larger sizes could partially block the migration of Mn⁴⁺ and Ru⁴⁺ from transition metal layer to Li layer, thus suppressing structural transformation of the system from layered-to-spinel phase. These findings may enable a new route for exploring ternary or even quaternary lithium-rich cathode materials for LIBs.

Microstructural Evolution and Phase Formation in 2nd-Generation Refractory-Based High Entropy Alloys

Refractory-based high entropy alloys (HEAs) of the 2nd-generation type are new intensively-studied materials with a high potential for structural high-temperature applications. This paper presents investigation results on microstructural evolution and phase formation in as-cast and subsequently heat-treated HEAs at various temperature-time regimes. Microstructural examination was performed by means of scanning electron microscopy (SEM) combined with the energy dispersive spectroscopy (EDS) mode of electron probe microanalysis (EPMA) and qualitative X-ray diffraction (XRD). The primary evolutionary trend observed was the tendency of Zr to gradually segregate as the temperature rises, while all the other elements eventually dissolve in the BCC solid solution phase once the onset of Laves phase complex decomposition is reached. The performed thermodynamic modelling was based on the Calculation of Phase Diagrams method (CALPHAD). The BCC A2 solid solution phase is predicted by the model to contain increasing amounts of Cr as the temperature rises, which is in perfect agreement with the actual results obtained by SEM. However, the model was not able to predict the existence of the Zr-rich phase or the tendency of Zr to segregate and form its own solid solution—most likely as a result of the Zr segregation trend not being an equilibrium phenomenon.

Crystal structures of the solid solutions Na3Zn0.912Cd0.088B5O10 and Na3Zn0.845Mg0.155B5O10

The solid solutions Na₃Zn_0.912Cd_0.088B₅O₁₀ and Na₃Zn_0.845Mg_0.155B₅O₁₀ adopt the ortho­rhom­bic form of the parent compound Na₃ZnB₅O₁₀ where parts of the zinc cations are replaced by cadmium and magnesium cations, respectively.

Two new penta­borates, tris­odium zinc cadmium penta­borate, Na₃Zn_0.912Cd_0.088B₅O₁₀, and tris­odium zinc magnesium penta­borate, Na₃Zn_0.845Mg_0.155B₅O₁₀, have been synthesized by high-temperature solution reactions at 1023 K. Their crystal structures were determined by single-crystal X-ray diffraction. Both solid solutions crystallize in the ortho­rhom­bic form of the parent compound Na₃ZnB₅O₁₀ (space group type Pbca, Z = 8) and contain the double ring [B₅O₁₀]⁵⁻ anion composed of one BO₄ tetra­hedron and four BO₃ triangles as the basic structural motif. The anions are bridged by tetra­hedrally coordinated and occupationally disordered M²⁺ (M = Zn/Cd, Zn/Mg) cations via common O atoms to form [MB₅O₁₀]_n³ⁿ⁻ layers. The intra­layer inter­secting channels and the inter­layer voids are occupied by Na⁺ cations to balance the charge.

Correlation of Structure, Tunable Colors, and Lifetimes of (Sr, Ca, Ba)Al₂O₄:Eu2+, Dy3+ Phosphors

(Sr, Ca, Ba)Al₂O₄:Eu²⁺, Dy³⁺ phosphors were prepared via a high temperature solid-state reaction method. The correlation of phase structure, optical properties and lifetimes of the phosphors are investigated in this work. For the (Sr, Ca)Al₂O₄:Eu²⁺, Dy³⁺ phosphors, the different phase formation from monoclinic SrAl₂O₄ phase to hexagonal SrAl₂O₄ phase to monoclinic CaAl₂O₄ phase was observed when the Ca content increased. The emission color of SrAl₂O₄:Eu²⁺, Dy³⁺ phosphors varied from green to blue. For the (Sr, Ba)Al₂O₄:Eu²⁺, Dy³⁺ phosphors, different phase formation from the monoclinic SrAl₂O₄ phase to the hexagonal BaAl₂O₄ phase was observed, along with a shift of emission wavelength from 520 nm to 500 nm. More interestingly, the decay time of SrAl₂O₄:Eu²⁺, Dy³⁺ changed due to the different phase formations. Lifetime can be dramatically shortened by the substitution of Sr²⁺ with Ba²⁺ cations, resulting in improving the performance of the alternating current light emitting diode (AC-LED). Finally, intense LEDs are successfully obtained by combining these phosphors with Ga(In)N near UV chips.

A 2D Substitutional Solid Solution through Hydrogen Bonding of Molecular Building Blocks

Two-dimensional (2D) molecular self-assembly allows for the formation of well-defined supramolecular layers with tailored geometrical, compositional, and chemical properties. To date, random intermixing and entropic effects in these systems have largely been associated with crystalline disorder and glassy phases. Here we describe a 2D crystalline self-assembled molecular system that exhibits random incorporation of substitutional molecules. The lattice is formed from a mixture of trimesic acid (TMA) and terthienobenzenetricarboxylic acid (TTBTA), C₃-symmetric hydrogen-bonding units of very different sizes (0.79 and 1.16 nm, respectively), at the solution-highly oriented pyrolitic graphite (HOPG) interface. Remarkably, the TTBTA substitutes into the TMA lattice at a fixed stoichiometry near 12%. The resulting lattice constant is consistent with Vegard's law prediction for an alloy with a composition TMA_0.88TTBTA_0.12, and the substrate orientation of the lattice is defined by an epitaxial relation with the HOPG substrate. The Gibbs free energy for the TMA/TTBTA lattice was elucidated by considering the entropy of intermixing, via Monte Carlo simulations of multiplicity of the substitutional lattices, and the enthalpy of intermixing, via density functional theory calculations. The latter show that both the bond enthalpy of the H-bonded lattice and the adsorption enthalpy of the molecule/substrate interactions play important roles. This work provides insight into the manifestation of entropy in a molecular crystal constrained by both epitaxy and intermolecular interactions and demonstrates that a randomly intermixed yet crystalline 2D solid can be formed through hydrogen bonding of molecular building blocks of very different size.

Photocatalytic Mechanism Regulation of Bismuth Oxyhalogen via Changing Atomic Assembly Method

Exciton and carrier photocatalytic processes have been proved in bismuth oxyhalogen photocatalysts. But, there are no reports about how to regulate the different mechanisms to improve photocatalytic activity for different reaction. Here, we found that the photocatalytic mechanisms could be regulated by changing the assembly method of bismuth, oxygen, and halogen atoms. Reactive oxygen species (ROS) experimentals results concluded that solid solution BiOBr_0.5I_0.5 showed enhanced exciton photocatalytic process, and coupling 0.5BiOBr/0.5BiOI displayed improved carrier photocatalytic proces. This work promoted the understanding about solid solution and coupling for bismuth oxyhalogen.

Crystal structure of the tetra-hydro-furan disolvate of a 94:6 solid solution of [N2,N6-bis-(di-tert-butyl-phosphan-yl)pyridine-2,6-di-amine]-dibromido-manganese(II) and its monophosphine oxide analogue

The MnBr₂ complex of N²,N⁶-bis­(di-tert-butyl­phosphan­yl)pyridine-2,6-di­amine (1·MnBr₂) co-crystallizes with 5.69% of the monophosphine oxide analogue (1O·MnBr₂) and two tetra­hydro­furan (THF) mol­ecules, namely {N²,N⁶-bis­(di-tert-butyl­phosphan­yl)pyridine-2,6-di­amine}­dibromido­manganese(II)–[bis­(di-tert-butyl­phosphan­yl)({6-[(di-tert-butyl­phosphan­yl)amino]­pyridin-2-yl}amino)­phosphine oxide]di­bromido­manganese(II)–tetra­hydro­furan (0.94/0.06/2), [MnBr₂(C₂₁H₄₁N₃P₂)]_0.94[MnBr₂(C₂₁H₄₁N₃OP₂)]_0.06·2C₄H₈O. The 1·MnBr₂ and 1O·MnBr₂ complexes are connected by weak N—H⋯Br hydrogen bonding into chains extending along [001] with the THF mol­ecules located between the layers formed by these chains.

The MnBr₂ complex of N²,N⁶-bis­(di-tert-butyl­phosphan­yl)pyridine-2,6-di­amine (1·MnBr₂) co-crystallizes with 5.69% of the monophosphine oxide analogue (1O·MnBr₂) and two tetra­hydro­furan (THF) mol­ecules, namely [N²,N⁶-bis­(di-tert-butyl­phosphan­yl)pyridine-2,6-di­amine]­dibromido­manganese(II)–[bis­(di-tert-butyl­phosphan­yl)({6-[(di-tert-butyl­phosphan­yl)amino]­pyridin-2-yl}amino)­phosphine oxide]di­bromido­manganese(II)–tetra­hydro­furan (0.94/0.06/2), [MnBr₂(C₂₁H₄₁N₃P₂)]_0.94[MnBr₂(C₂₁H₄₁N₃OP₂)]_0.06·2C₄H₈O. The 1·MnBr₂ and 1O·MnBr₂ complexes are occupationally disordered about general positions. Both complexes feature square-pyramidal coordination of the Mn^II atoms. They are connected by weak N—H⋯Br hydrogen bonding into chains extending along [001]. The THF mol­ecules are located between the layers formed by these chains. One THF mol­ecule is involved in hydrogen bonding to an amine H atom.

Experimental and Computational Hydrate Screening: Cytosine, 5-Flucytosine and Their Solid Solution

The structural, temperature- and moisture dependent stability features of cytosine and 5-flucytosine monohydrates, two pharmaceutically important compounds, were rationalized using complementary experimental and computational approaches. Moisture sorption/desorption, water activity, thermal analysis and calorimetry were applied to determine the stability ranges of hydrate ↔ anhydrate systems, while X-ray diffraction, IR spectroscopy and crystal structure prediction provided the molecular level understanding. At 25 °C, the critical water activity for the cytosine hydrate ↔ anhydrate system is ~0.43 and for 5-flucytosine ~0.41. In 5-flucytosine the water molecules are arranged in open channels, therefore the kinetic desorption data, dehydration < 40% relative humidity (RH), conform with the thermodynamic data, whereas for the cytosine isolated site hydrate dehydration was observed at RH < 15%. Peritectic dissociation temperatures of the hydrates were measured to be 97 °C and 84.2 °C for cytosine and 5-flucytosine, respectively, and the monohydrate to anhydrate transition enthalpies to be around 10 kJ mol-1. Computed crystal energy landscapes not only revealed that the substitution of C5 (H or F) controls the packing and properties of cytosine/5-flucytosine solid forms, but also have enabled the finding of a monohydrate solid solution of the two substances which shows increased thermal- and moisture-dependent stability compared to 5-flucytosine monohydrate.

Simultaneous Ni Doping at Atom Scale in Ceria and Assembling into Well-Defined Lotuslike Structure for Enhanced Catalytic Performance

Oxide materials with redox capability have attracted worldwide attentions in many applications. Introducing defects into crystal lattice is an effective method to modify and optimize redox capability of oxides as well as their catalytic performance. However, the relationship between intrinsic characteristics of defects and properties of oxides has been rarely reported. Herein, we report a facile strategy to introduce defects by doping a small amount of Ni atoms (∼1.8 at. %) into ceria lattice at atomic level through the effect of microstructure of crystal on the redox property of ceria. Amazingly, a small amount of single Ni atom-doped ceria has formed a homogeneous solid solution with uniform lotuslike morphology. It performs an outstanding catalytic performance of a reduced T₅₀ of CO oxidation at 230 °C, which is 135 °C lower than that of pure CeO₂ (365 °C). This is largely attributed to defects such as lattice distortion, crystal defects and elastic strain induced by Ni dopants. The DFT calculation has revealed that the electron density distribution of oxygen ions near Ni dopant, the reduced formation energy of oxygen vacancy originated from local chemical effect caused by local distortion after Ni doping. These differences have a great effect on increasing the concentration of oxygen vacancies and enhancing the migration of lattice oxygen from bulk to a surface which is closely related to optimized redox properties. As a result, oxygen storage capacity and the associated catalytic reactivity has been largely increased. We have clearly demonstrated the change of crystal lattice and the charge distribution effectively modify its chemical and physical properties at the atomic scale.

Effects of Pr₆O11 Addition on the Acid Resistance of Ceramic Proppant

This paper investigated the effect of Pr₆O₁₁ addition on the acid resistance of ceramic proppant. Acid resistance of proppants can be improved by introducing Pr₆O₁₁ into the Al₂O₃-CaO-MgO-SiO₂ (ACMS) system. To illustrate and explain the mechanism of acid resistance, the samples were characterized by different techniques, using X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The phase structure of the specimens was characterized by XRD and SEM-detected microstructures of the specimens. It was observed that with the increase of rare-earth oxide content, the acid solubility of the specimens decreased, and then increased when it reached the minimum value 0.45 wt %. The results of the research show that the improvement of acid resistance with rare-earth oxides was achieved by refining the grain size, strengthening the grain boundary, and turning Ca₂Al₂SiO₇, in which acid resistance is poor, into CaAl₁₂O₁₉, which possesses better acid resistance, and then enhance the acid resistance of the proppants. Furthermore, Pr₆O₁₁ can form a solid solution with Ca₂Al₂SiO₇ and CaAl₁₂O₁₉. The acid resistance of CaAl₁₂O₁₉ improves with the increase of solid solubility. In contrast, the acid resistance of Ca₂Al₂SiO₇ will decrease after Ca₂Al₂SiO₇ forms a solid solution with Pr₆O₁₁.

Substitution of indium for chromium in TlIn5-x Cr x Se8: crystal structure of TlIn4.811(5)Cr0.189(5)Se8

The new thallium penta-(indium/chromium) octa-selenide, TlIn_4.811(5)Cr_0.189(5)Se₈, has been synthesized by solid-state reaction. It crystallizes isotypically with TlIn₅Se₈ in the space group C2/m. Although the two Tl positions are disordered and only partially occupied, no Tl deficiency was observed. The insertion of chromium in the structure has been confirmed by EDS analysis. Chromium substitutes indium exclusively at one of three In sites, viz. at one of the positions with site symmetry 2/m (Wyckoff position 2a). In the crystal structure, edge-sharing InSe₆ octa-hedra, and (In,Cr)Se₆ octa-hedra and InSe₄ tetra-hedra make up two types of columns that are linked into a framework in which two different types of channels parallel to [010] are present. The Tl atoms are located in the larger of the channels, whereas the other, smaller channel remains unoccupied.

Synergistic Strategy to Enhance the Thermoelectric Properties of CoSbS1-xSex Compounds via Solid Solution

High thermal conductivity of CoSbS-based limited its own prospect application in thermoelectric energy conversion. Solid solution is an effective approach to optimize the performance of thermoelectric materials with high lattice thermal conductivity because of the enhanced phonons scattering from disorder atoms. In this paper, we have synthesized and measured the thermoelectric properties of solid solution CoSbS_1-xSe_x (x = 0, 0.05, 0.10, 0.15, 0.20, 0.30) series samples. The collaborative optimization (enhancing the power factors and reducing the thermal conductivities) to add zT values were realized via substitution of S atoms with the isoelectronic Se atoms in the matrix. Meanwhile, the lowest room temperature lattice thermal conductivity in CoSbS-based materials is obtained (4.72 W m^-1 K^-1) at present. Benefiting from the results of synergistic strategy, a zT of 0.35 was achieved at 923 K for sample CoSbS_0.85Se_0.15, a 59% improvement as compared with that of the pristine CoSbS. Band calculation demonstrated that CoSbS_0.85Se_0.15 present a similar band dispersion with CoSbS. The mechanism of point defect scattering for reducing the lattice thermal conductivity at room temperature, was also analyzed by the Callaway model. The contributions to decrease the room temperature lattice thermal conductivity from the mass and the strain fluctuation in the crystal are comparable. These results can also be extended to other high-efficiency thermoelectric materials with stiff bond and smaller Gruneisen parameters.

Direct Single-Enzyme Biomineralization of Catalytically Active Ceria and Ceria-Zirconia Nanocrystals

Biomineralization is an intriguing approach to the synthesis of functional inorganic materials for energy applications whereby biological systems are engineered to mineralize inorganic materials and control their structure over multiple length scales under mild reaction conditions. Herein we demonstrate a single-enzyme-mediated biomineralization route to synthesize crystalline, catalytically active, quantum-confined ceria (CeO_2-x) and ceria-zirconia (Ce_1-yZr_yO_2-x) nanocrystals for application as environmental catalysts. In contrast to typical anthropogenic synthesis routes, the crystalline oxide nanoparticles are formed at room temperature from an otherwise inert aqueous solution without the addition of a precipitant or additional reactant. An engineered form of silicatein, rCeSi, as a single enzyme not only catalyzes the direct biomineralization of the nanocrystalline oxides but also serves as a templating agent to control their morphological structure. The biomineralized nanocrystals of less than 3 nm in diameter are catalytically active toward carbon monoxide oxidation following an oxidative annealing step to remove carbonaceous residue. The introduction of zirconia into the nanocrystals leads to an increase in Ce(III) concentration, associated catalytic activity, and the thermal stability of the nanocrystals.

Crystal structure of the solid solution Ba8.35Pb0.65(B3O6)6

The fundamental building units of Ba_8.35Pb_0.65(B₃O₆)₆ are isolated planar B₃O₆ anionic groups, which are distributed layer upon layer perpendicular to [001], with (Pb/Ba) and Ba sites alternately located between the B₃O₆ sheets.

Single crystals of lead barium borate, Ba_8.35Pb_0.65(B₃O₆)₆, octabarium lead(II) hexa­kis­(triborate), have been obtained by spontaneous nucleation from a high-temperature melt. Its three-dimensional structure is constructed on the basis of a BaO₉ polyhedron, a (Pb/Ba)O₆ octa­hedron (occupancy ratio Pb:Ba = 0.216:0.784) and a condensed B₃O₆ ring anion. In the crystal, the planar B₃O₆ anions are stacked in an alternating fashion with Ba and (Pb/Ba) atoms along [001]. A comparison is made with the structures of related solid solutions in the system Ba/Pb/B/O.

Mechanistic insights into acyclovir-polyethylene glycol 20000 binary dispersions

Objective:

The objective of this study is to provide a mechanistic insight into solubility enhancement and dissolution of acyclovir (ACY) by polyethylene glycol20000 (PEG20000).

Materials and Methods:

Solid dispersions with differing ratios of drug (ACY) and carrier (PEG20000) were prepared and evaluated by phase solubility, in vitro release studies, kinetic analysis, in situ perfusion, and in vitro permeation studies. Solid state characterization was also done by Powder X-Ray Diffraction (PXRD), Differential Scanning Calorimetry (DSC), Fourier Transform Infrared spectroscopy (FT-IR) analysis and surface morphology was assessed by Polarizing Microscopic Image (PMI) analysis, Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and Nuclear Magnetic Resonance (NMR) analysis.

Results:

Thermodynamic parameters proved the solubilization effect of carrier. The aqueous solubility and dissolution of ACY were increased in all samples. Formation of solid solution, crystallinity reduction, and absence of interaction between drug and carrier was proved by XRD, DSC, and FTIR analysis. The particle size reduction and change in surface morphology were confirmed by SEM and AFM and analysis. The permeation coefficient and amount of drug diffused was higher in samples as compared to ACY. The stability was high in dispersions, and it was proved by NMR analysis.

Conclusion:

The mechanical insights into the enhancement of solubility and dissolution could be used as a platform to improve the aqueous solubility for other poor water soluble drugs.

An Ideal Solid Solution Model for C-S-H

A model for an ideal solid solution, developed by Nourtier-Mazauric et al. [Oil & Gas Sci. Tech. Rev. IFP, 60 [2] (2005) 401], is applied to calcium-silicate-hydrate (C-S-H). Fitting the model to solubility data reported in the literature for C-S-H yields reasonable values for the compositions of the end-members of the solid solution and for their equilibrium constants. This model will be useful in models of hydration kinetics of tricalcium silicate because it is easier to implement than other solid solution models, it clearly identifies the driving force for growth of the most favorable C-S-H composition, and it still allows the model to accurately capture variations in C-S-H composition as the aqueous solution changes significantly at early hydration times.

Controlling Shape Anisotropy of ZnS-AgInS2 Solid Solution Nanoparticles for Improving Photocatalytic Activity

Independently controlling the shape anisotropy and chemical composition of multinary semiconductor particles is important for preparing highly efficient photocatalysts. In this study, we prepared ZnS-AgInS₂ solid solution ((AgIn)_xZn_2(1-x)S₂, ZAIS) nanoparticles with well-controlled anisotropic shapes, rod and rice shapes, by reacting corresponding metal acetates with a mixture of sulfur compounds with different reactivities, elemental sulfur, and 1,3-dibutylthiourea, via a two-step heating-up process. The chemical composition predominantly determined the energy gap of ZAIS particles: the fraction of Zn²⁺ in rod-shaped particles was tuned by the ratio of metal precursors used in the nanocrystal formation, while postpreparative Zn²⁺ doping was necessary to increase the Zn²⁺ fraction in the rice-shaped particles. The photocatalytic H₂ evolution rate with irradiation to ZAIS particles dispersed in an aqueous solution was significantly dependent on the chemical composition in the case of using photocatalyst particles with a constant morphology. In contrast, photocatalytic activity at the optimum ZAIS composition, x of 0.35-0.45, increased with particle morphology in the order of rice (size: ca. 9 × ca. 16 nm) < sphere (diameter: ca. 5.5 nm) < rod (size: 4.6 × 27 nm). The highest apparent quantum yield for photocatalytic H₂ evolution was 5.9% for rod-shaped ZAIS particles, being about two times larger than that obtained with spherical particles.

Optimizing Blue Persistent Luminescence in (Sr1-δBaδ)2MgSi2O7:Eu2+,Dy3+ via Solid Solution for Use in Point-of-Care Diagnostics

Inorganic persistent luminescent phosphors are an excellent class of optical reporters for enabling sensitive point-of-care diagnostics, particularly with smartphone-based biosensing devices in testing formats such as the lateral flow assay (LFA). Here, the development of persistent phosphors for this application is focused on the solid solution (Sr_1-δBa_δ)₂MgSi₂O₇:Eu²⁺,Dy³⁺ (δ = 0, 0.125, 0.25, 0.375), which is prepared using a high-temperature solid-state reaction as confirmed by synchrotron X-ray powder diffraction. The substitution of barium for strontium enables control over the Eu²⁺ 5d-orbital crystal field splitting (CFS) as a tool for tuning the emission wavelength while maintaining luminescence lifetimes >9 min across the composition range. Thermoluminescence measurements of the solid solution provide evidence that trap states contribute to the persistent lifetimes with the trap depths also remaining constant as a function of composition. Time-gated luminescence images of these compounds are captured on a smartphone arranged in a layout to mimic a point-of-care test and demonstrate the viability of using these materials as optical reporters. Moreover, comparing the blue-emitting (Sr_0.625Ba_0.375)₂MgSi₂O_7:Eu²⁺,Dy³⁺ and the green-emitting SrAl₂O₄:Eu²⁺,Dy³⁺ in a single LFA-type format shows these two compounds can be detected and resolved simultaneously, thereby permitting the development of a multiplexed LFA.

Solid Solution Photocatalyst with Spontaneous Polarization Exhibiting Low Recombination Toward Efficient CO2 Photoreduction

Decreasing the recombination of photogenerated carriers is a major challenge for efficiently converting solar energy into chemical energy by photocatalysis. Here, we have demonstrated that growth of a polar GaN:ZnO solid solution single crystal along its polarization axis is beneficial to efficient separation of photogenerated carriers, owing to the periodic potential barriers and wells generated from the periodically positive and negative atom arrangements in crystal structure. Local charge imbalance caused by replacing Ga(3+) with Zn(2+) leads to a polarization vector in the {0 0 0 1} planes of GaN:ZnO solid solution, thus forming a 1 D electron transport path along [2 1‾  1‾  0] in the {0 0 0 1} planes of GaN:ZnO solid solution to decrease recombination. Shorting the hole-transport distance by synthesizing porous nanoplates can further decrease recombination under the polarization field and improve the performance of polar photocatalyst in photoreduction of CO2 into CH4 .

High-Performance Hydrogen Evolution from MoS2(1-x) P(x) Solid Solution

A MoS2(1-x) P(x) solid solution (x = 0 to 1) is formed by thermally annealing mixtures of MoS2 and red phosphorus. The effective and stable electrocatalyst for hydrogen evolution in acidic solution holds promise for replacing scarce and expensive platinum that is used in present catalyst systems. The high performance originates from the increased surface area and roughness of the solid solution.

A single Eu2+-activated high-color-rendering oxychloride white-light phosphor for white-light-emitting diodes

Single-phased, high-color-rendering index (CRI) white-light phosphors are emerging as potential phosphor-converted white-light-emitting diodes (WLEDs) and as an alternative to blends of tricolor phosphors. However, it is a challenge to create a high CRI white light from a single-doped activator. Here, we present a high CRI (Ra = 91) white-light phosphor, Sr₅(PO₄)_3-x(BO₃)_xCl:Eu²⁺, composed of Sr₅(PO₄)₃Cl as the beginning member and Sr₅(BO₃)₃Cl as the end member. This work utilized the solid-solution method, and tunable Eu²⁺ emission was achieved. Color-tunable Eu²⁺ emissions in response to structural variation were observed in Sr₅(PO₄)_3-x(BO₃)_xCl solid solutions. This was further confirmed using X-ray Rietveld refinement, electron paramagnetic resonance spectroscopy, and in the photoluminescence spectra. The color-tunable emissions included the white light that originated from the combination of the blue emission of Sr₅(PO₄)₃Cl:Eu²⁺ and an induced Eu²⁺ yellow emission at approximately 550 nm in the solid solution. Importantly, the white-light phosphors showed a greater R9 = 90.2 under excitation at 365 nm. This result has rarely been reported in the literature and is greater than that of (R9 = 14.3) commercial Y₃A_l5O₁₂:Ce³⁺-based WLEDs. These findings demonstrate the great potential of Sr₅(PO₄)_3-x(BO₃)_xCl:0.04Eu²⁺ as a white-light phosphor for near-UV phosphor-converted WLEDs. These results also provide a shortcut for developing a high CRI white-light phosphor from a single Eu²⁺-doped compound.

Hot melt extrusion based solid solution approach: Exploring polymer comparison, physicochemical characterization and in-vivo evaluation

The objective of this study was to develop solid solution (SSL) using hot-melt extrusion as a continuous manufacturing method. Powder blends of artesunate (ARS) a water insoluble drug with either Soluplus (SOL) or Kollidon VA64 (VA64) and additives in the form of surfactants or plasticizers were extruded to manufacture extrudes. The incorporation of surfactant or plasticizers facilitates smooth extrusion processing of the drug-excipient blend which directly reduced the residence time to form extrudes and works as parameter to control flow of the drug-excipients melt inside the extruder barrel. Differential scanning calorimetry (DSC) and X-ray diffraction (TXRD) analysis revealed the existence of the drug within the extrudes in amorphous state. Scanning electron microscopy (SEM), Raman spectroscopy (RS), Raman imaging (RI) and Atomic force microscopy (AFM) analytical characterization were carry out on the SSL formulations showed a homogeneous drug distribution within the extrudes. (2)D NMR and (1)H NMR studies were undertaken to reveal the possible drug-excipient interactions. The SSL produced via continuous HME processing showed significantly faster release of ARS compared to the pure drug substance. It is observed that F1 SSL (soluplus based) have 66.44 times higher AUC(0-72) and 16.60 times higher Cmax than pure ARS. Also K1 SSL (Kollidon VA64 based) have 62.20 times higher AUC(0-72) and 13.40 times higher Cmax than pure ARS.

Solution-Processed Ambipolar Organic Thin-Film Transistors by Blending p- and n-Type Semiconductors: Solid Solution versus Microphase Separation

Here, we report solid solution of p- and n-type organic semiconductors as a new type of p-n blend for solution-processed ambipolar organic thin film transistors (OTFTs). This study compares the solid-solution films of silylethynylated tetraazapentacene 1 (acceptor) and silylethynylated pentacene 2 (donor) with the microphase-separated films of 1 and 3, a heptagon-embedded analogue of 2. It is found that the solid solutions of (1)x(2)1-x function as ambipolar semiconductors, whose hole and electron mobilities are tunable by varying the ratio of 1 and 2 in the solid solution. The OTFTs of (1)0.5(2)0.5 exhibit relatively balanced hole and electron mobilities comparable to the highest values as reported for ambipolar OTFTs of stoichiometric donor-acceptor cocrystals and microphase-separated p-n bulk heterojunctions. The solid solution of (1)0.5(2)0.5 and the microphase-separated blend of 1:3 (0.5:0.5) in OTFTs exhibit different responses to light in terms of absorption and photoeffect of OTFTs because the donor and acceptor are mixed at molecular level with π-π stacking in the solid solution.

Properties of Schottky Barrier Diodes on (In(x)Ga(1-x))₂O₃ for 0.01 ≤ x ≤ 0.85 Determined by a Combinatorial Approach

We investigated properties of an (In(x)Ga(1-x))2O3 thin film with laterally varying cation composition that was realized by a large-area offset pulsed laser deposition approach. Within a two inch diameter thin film, the composition varies between 0.01 ≤ x ≤ 0.85, and three crystallographic phases (cubic, hexagonal, and monoclinic) were identified. We observed a correlation between characteristic parameters of Schottky barrier diodes fabricated on the thin film and its chemical and structural material properties. The highest Schottky barriers and rectification of the diodes were found for low indium contents. The thermal stability of the diodes is also best for Ga-rich parts of the sample. Conversely, the series resistance is lowest for large In content. Overall, the (In(x)Ga(1-x))2O3 alloy is well-suited for potential applications such as solar-blind photodetectors with a tunable absorption edge.

Facile Synthesis of n-type (AgIn)(x)Zn(2(1-x))S2/p-type Ag2S Nanocomposite for Visible Light Photocatalytic Reduction To Detoxify Hexavalent Chromium

n-type (AgIn)(x)Zn(2(1-x))S2/p-type Ag2S nanocomposites with 10%, 20%, and 30% Ag2S loading were successfully synthesized via the simple solvothermal and sol gel methods. The as-prepared nanocomposites were characterized, and their visible light photocatalytic reductions were tested for detoxification of hexavalent chromium (Cr(VI)). The results showed only 20 mg of the as-prepared nanocomposites could reduce 100 mL of 20 ppm potassium dichromate by almost 100% in less than 90 min without adding any hole scavenger agents and pH adjustment (pH = 7). The good photocatalytic reduction was related to the narrower bandgap of (AgIn)(x)Zn(2(1-x))S2 solid solution because of the hybridized orbitals of Ag, In, Zn, and S and low recombination rate of photogenerated electron and hole pairs due to the effectiveness of p-type Ag2S and n-type (AgIn)(x)Zn(2(1-x))S2 nanoheterojunctions. This work not only gives a contribution to the creation of visible light photocatalysis for wide-bandgap semiconductors, but also extends our technological viewpoints in designing highly efficient metal sulfide photocatalyst. To the best of our knowledge, this work is the first finding of a high photocatalytic reduction of hexavalent chromium under visible light illumination by simultaneously using both concepts of p-n nanoheterojunction and solid solution in our photocatalyst design. In this present work, these concepts were used to replace the use of hole scavenger agents, which were commonly used by many other works to retard the recombination rate of photoinduced electron and hole pairs for photodegradation of hexavalent chromium.

Incommensurate modulation and thermal expansion of Sr3B(2 + x)Si(1 - x)O(8 - x/2) solid solutions

Crystal structures of Sr3B(2 + x)Si(1 - x)O(8 - x/2) solid solutions with nominal compositions x = 0.28, 0.53, 0.78 in the Sr3B2SiO8-Sr2B2O5 section of the SrO-B2O3-SiO2 system are refined using single-crystal X-ray diffraction data. Incommensurate structure modulations are mainly associated with various orientations of corner-sharing (B,Si)-polyhedra. Preference is given to the (3 + 2)-dimensional symmetry group Pnma(0βγ)000(0βγ)000 for a single crystal compared with an alternate model of a twin formed by monoclinic components, each of them corresponding to the (3 + 1)-dimensional symmetry group P2(1)/n(0βγ). Single-phase polycrystalline samples of solid solutions are investigated by high-temperature X-ray powder diffraction in air. Orientation preferences of the BO3 units lead to a strong anisotropy of thermal expansion. Negative expansion is observed along the a axis over the temperature range 303-753 K. Anisotropy decreases both on heating and decreasing of the boron content.

Hollow Ball-in-Ball CoxFe3-xO4 Nanostructures: High-Performance Anode Materials for Lithium-Ion Battery

The intrinsic electronic conductivity can be improved by doping efficiently. CoxFe3-xO4 nanostructures have been synthesized for the first time to improve the conductivity of lithium battery electrode. The solid solution CoxFe3--xO4 were characterized by X-ray diffraction pattern (XRD), Raman spectrum, scanning electron microscopy (SEM), transmission electron microscope (TEM), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). The results show that the doping enlarge the lattice spacing but the structure of Co3O4 is stable in the Li-ion intercalation/deintercalation process. The AC impedance spectrum reveals the conductivity is well improved. In addition, the solid solution CoxFe3-xO4 exhibit excellent electrochemical characteristics. The electrodes with 20% molar ratio of Fe ions own a reversible capacity of 650.2 mA h g(-1) at a current density of 1 A g(-1) after 100 cycles.

Utilization of Metal Sulfide Material of (CuGa)(1-x)Zn(2x)S2 Solid Solution with Visible Light Response in Photocatalytic and Photoelectrochemical Solar Water Splitting Systems

Upon forming a solid solution between CuGaS2 and ZnS, we have successfully developed a highly active (CuGa)(1-x)Zn(2x)S2 photocatalyst for H2 evolution in the presence of sacrificial reagents under visible light irradiation. The Ru-loaded (CuGa)0.8Zn0.4S2 functioned as a H2-evolving photocatalyst in a Z-scheme system with BiVO4 of an O2-evolving photocatalyst and Co complexes of an electron mediator. The Z-scheme system split water into H2 and O2 under visible light and simulated sunlight irradiation. The (CuGa)(1-x)Zn(2x)S2 possessed a p-type semiconductor character. The photoelectrochemical cell with a Ru-loaded (CuGa)0.5ZnS2 photocathode and a CoO(x)-modified BiVO4 photoanode split water even without applying an external bias. Thus, we successfully demonstrated that the metal sulfide material group can be available for Z-scheme and electrochemical systems to achieve solar water splitting into H2 and O2.

Solid tryptophan as a pseudoracemate: physicochemical and crystallographic characterization

The crystalline nature of solid tryptophan has been characterized by X-ray single crystal and powder diffraction analyses, differential scanning calorimetry, as well as measurement of solid-liquid equilibrium in water/isopropanol solution. Both the thermodynamic and crystallographic investigations have demonstrated unambiguously that solid tryptophan crystallizes in the form of a pseudoracemate (i.e., solid solution) with maximum melting over the entire enantiomeric composition range. Comparative single-crystal X-ray studies show that the crystal structures of racemic and enantiomeric tryptophan give very similar solid-state packing geometries dictated by hydrogen bonding interactions. Our results indicate that the insignificant difference between homochiral and heterochiral interactions accounts for the formation of a pseudoracemate for this system.

Structural disorder and transformation in crystal growth: direct observation of ring-opening isomerization in a metal-organic solid solution

A rare example is reported in which discrete Ag2 L 2 ring and (AgL)∞ chain motifs [L = N,N'-bis(3-imidazol-1-yl-propyl)-pyromellitic diimide] co-crystallize in the same crystal lattice with varying ratios and degrees of disorder. Crystal structures obtained from representative crystals reveal compatible packing arrangements of the cyclic and polymeric isomers within the crystal lattice, which enables them to co-exist within a crystalline solid solution. A feasible pathway for transformation between the isomers is suggested via facile rotation of the coordinating imidazolyl groups. This chemical system could provide a chance for direct observation of ring-opening isomerization at the crystal surface. Mass spectrometry and (1)H NMR titration show a dynamic equilibrium between cyclic and oligomeric species in solution, and a potential crystallization process is suggested involving alignment of precursors directed by aromatic stacking interactions between pyromellitic diimide units, followed by ring-opening isomerization at the interface between the solid and the solution. Both cyclic and oligomeric species can act as precursors, with interconversion between them being facile due to a low energy barrier for rotation of the imidazole rings. Thermogravimetric analysis and variable-temperature powder X-ray diffraction indicate a transition to a different crystalline phase around 120°C, which is associated with loss of solvent from the crystal lattice.

Crystal structure of the solid solution (Sr1.65Pb0.35)Al6O11

The title compound, di(strontium/lead) hexa-aluminate, is a member of the solid solution series (Sr2-x Pb x )Al6O11. It contains two statistically occupied M (2+) (M = Sr, Pb) sites [both with site symmetries ..m; Sr:Pb occupancy ratios = 0.756 (2):0.244 (2) and 0.8968 (19):0.1032 (19)] that are located in the voids of an aluminate framework. The M (2+) sites are surrounded by six and seven O atoms, respectively, if a cut-off M-O distance of 3 Å is chosen, resulting in considerably distorted MO x polyhedra. The aluminate framework consists of three AlO6 octa-hedra (two with point-group symmetries ..2/m and one with ..2) sharing edges to form partially filled layers extending parallel to (100) and located at x = 0, 0.5. Adjacent AlO6 layers are linked by a network made up from two crystallographically different AlO4 tetra-hedra by sharing corners.

Determination of the solubility of crystalline low molar mass compounds in polymers by differential scanning calorimetry

A mathematical equation has been derived to calculate the liquidus for a binary system consisting of an amorphous polymer and a crystalline low molar mass compound. The experimental input to this equation is an interaction enthalpy, which is derived from the variation of the melting enthalpy with composition in differential scanning calorimetry (DSC) experiments. The predictive power of the equation has been tested with mixtures of acetylsalicylic acid, carbamazepine, or intraconazole with poly(ethylene glycol) as well as mixtures of carbamazepine with poly(acrylic acid), poly(hydroxystyrene), or poly(vinylpyrrolidone). It has been confirmed that the evaluation of the melting enthalpy in DSC is a suitable method to identify the preferred solute-polymer combinations for thermodynamically stable molecular dispersions.