The CeFe11Ti permanent magnet: a closer look at the microstructure of the compound

High-performance permanent magnets (PM) are compounds with outstanding intrinsic magnetic properties. Most PMs are obtained from a favorable combination of rare earth metals (RE  =  Nd, Pr, Ce) with transition metals (TM  =  Fe, Co). Amongst them, CeFe₁₁Ti claims considerable attention due to its large Curie temperature, saturation magnetization, and significant magnetocrystalline anisotropic energy. CeFe₁₁Ti has several potential applications, in particular, in the development of electric motors for future automatic electrification. In this work, we shed some light on the mictrostructure of this compound by performing periodic hybrid-exchange density functional theory (DFT) calculations. We use a combined approach of atom-centered local orbitals, plane waves and full-potential linear muffin-tin orbital (LMTO) for our computations. The electronic configuration of the atoms involved in different steps of formation of the crystal structure of CeFe₁₁Ti gives an explanation on the effect of Ce and Ti on its magnetic properties. While Ti stabilizes the structure, atomic orbitals of Ce hybridizes with Fe atomic orbitals to a significant extent and alters the electronic bands. Our calculations confirm a valence of 3⁺ for Ce, which has been deemed crucial to obtain a large magnetocrystalline anisotropy. In addition, we analyze several spin configurations, with the ferromagnetic configuration being most stable. We compare and contrast our data to those available and provide an insight for further development of optimized high-performance PMs. Moreover, we compute the Magnetocrystalline Anisotropy of this compound by means of two approaches: the Force Theorem and a full-potential LMTO method.

Benzoquinone-Bridged Heterocyclic Zwitterions as Building Blocks for Molecular Semiconductors and Metals

In pursuit of closed-shell building blocks for single-component organic semiconductors and metals, we have prepared benzoquino-bis-1,2,3-thiaselenazole QS, a heterocyclic selenium-based zwitterion with a small gap (λ_max = 729 nm) between its highest occupied and lowest unoccupied molecular orbitals. In the solid state, QS exists in two crystalline phases and one nanocrystalline phase. The structures of the crystalline phases (space groups R3 c and P2₁/ c) have been determined by high-resolution powder X-ray diffraction methods at ambient and elevated pressures (0-15 GPa), and their crystal packing patterns have been compared with that of the related all-sulfur zwitterion benzoquino-bis-1,2,3-dithiazole QT (space group Cmc2₁). Structural differences between the S- and Se-based materials are interpreted in terms of local intermolecular S/Se···N'/O' secondary bonding interactions, the strength of which varies with the nature of the chalcogen (S vs Se). While the perfectly two-dimensional "brick-wall" packing pattern associated with the Cmc2₁ phase of QT is not found for QS, all three phases of QS are nonetheless small band gap semiconductors, with σ_RT ranging from 10^-5 S cm^-1 for the P2₁/ c phase to 10^-3 S cm^-1 for the R3 c phase. The bandwidths of the valence and conduction bands increase with applied pressure, leading to an increase in conductivity and a decrease in thermal activation energy E_act. For the R3 c phase, band gap closure to yield an organic molecular metal with a σ_RT of ∼10² S cm^-1 occurs at 6 GPa. Band gaps estimated from density functional theory band structure calculations on the ambient- and high-pressure crystal structures of QT and QS correlate well with those obtained experimentally.

Uptake and speciation of uranium in synthetic gypsum (CaSO4•2H2O): Applications to radioactive mine tailings

Phosphogypsum formed from the production of phosphoric acid represents by far the biggest accumulation of gypsum-rich wastes in the world and commonly contains elevated radionuclides, including uranium, as well as other heavy metals and metalloids. Therefore, billions-of-tons of phosphogypsum stockpiled worldwide not only possess serious environmental problems but also represent a potential uranium resource. Gypsum is also a major solid constituent in many other types of radioactive mine tailings, which stems from the common usage of sulfuric acid in extraction processes. Therefore, management and remediation of radioactive mine tailings as well as future beneficiation of uranium from phosphogysum all require detailed knowledge about the nature and behavior of uranium in gypsum. However, little is known about the uptake mechanism or speciation of uranium in gypsum. In this study, synthesis experiments suggest an apparent pH control on the uptake of uranium in gypsum at ambient conditions: increase in U from 16 μg/g at pH = 6.5 to 339 μg/g at pH = 9.5. Uranium L₃-edge synchrotron X-ray absorption spectroscopic analyses of synthetic gypsum show that uranyl (UO₂)²⁺ at the Ca site is the dominant species. The EXAFS fitting results also indicate that uranyl in synthetic gypsum occurs most likely as carbonate complexes and yields an average U-O distance ∼0.25 Å shorter than the average Ca-O distance, signifying a marked local structural distortion. Applications to phosphogypsum from the New Wales phosphoric acid plant (Florida, USA) and uranium mine tailings from the Key Lake mill (Saskatchewan, Canada) show that gypsum is an important carrier of uranium over a wide range of pH and controls the fate of this radionuclide in mine tailings. Also, development of new technologies for recovering U from phosphogypsum in the future must consider lattice-bound uranyl in gypsum.

Information as a distinct dimension for satisfaction assessment of outpatient psychiatric services

The purpose of this study is to verify whether information on services would appear as a distinct dimension of satisfaction in a multidimensional scale. Data collection was performed in two phases: 263 patients received the original version of the questionnaire and 200 received an adapted version of the scale. The findings suggest that not only is it important to consider information as a distinct dimension of satisfaction but it is equally important to examine three categories, consisting of satisfaction with information on; patients' problems/illness; distinct treatment components such as medication and psychotherapy; and patients' treatment progress.

Patients' perspective on their relatives' involvement in treatment during a short-term psychiatric hospitalization

With the growing interest in the patient's perspective regarding mental health services, several instruments have been developed for this area of research. However, despite the availability of multidimensional questionnaires, the dimensions evaluated have rarely addressed the issue of the involvement of relatives in treatment. The present study aimed at documenting the preferences and level of satisfaction of 92 patients hospitalized in short-term psychiatric units regarding the involvement of their relatives in treatment. Data was collected using an open-ended question and two standardized scales developed for the purposes of this study. The results demonstrated that the majority of patients preferred that their relatives be involved in many aspects of their treatment. In fact, a relatively high rate of dissatisfaction of 35.6% was observed among patients concerning the lack of notification of their relatives about changes in their treatment. In the context of deinstitutionalization, where relatives are invited to play an increasing role in the community reintegration of the patient, these findings highlight the pertinence of addressing the patient's perspective with regard to treatment planning with relatives.