1
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Silva RS, Rodrigues JE, Gainza J, Serrano-Sánchez F, Martínez L, Huttel Y, Martínez JL, Alonso JA. Magnetoelastic Coupling Evidence by Anisotropic Crossed Thermal Expansion in Magnetocaloric RSrCoFeO 6 (R = Sm, Eu) Double Perovskites. Inorg Chem 2024; 63:7007-7018. [PMID: 38557070 PMCID: PMC11022179 DOI: 10.1021/acs.inorgchem.4c00594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 03/15/2024] [Accepted: 03/19/2024] [Indexed: 04/04/2024]
Abstract
Double perovskite oxides, characterized by their tunable magnetic properties and robust interconnection between the lattice and magnetic degrees of freedom, present an enticing foundation for advanced magnetic refrigeration materials. Herein, we delve into the influence of rare-earth elements on RSrCoFeO6 (R = Sm, Eu) disordered double perovskites by examining their structural, electronic, magnetic, and magnetocaloric properties. Temperature-dependent synchrotron X-ray diffraction analysis confirmed the stability of the orthorhombic phase (Pnma) across a wide temperature range. X-ray photoemission spectroscopy revealed that both Sm and Eu are in the 3+ state, whereas multiple states for Co2+/3+ and Fe3+/4+ are identified. The magnetic investigation and magnetocaloric effect (MCE) analysis brought to light the presence of a long-range antiferromagnetic (AFM) order with a second-order phase transition (SOPT) in both samples. The maximum magnetic entropy change ΔSMmax was approximately 0.9 J/kg K for both samples at applied field 0-7 T, manifesting prominently above Neel temperatures TN ≈ 93 K (Sm) and 84 K (Eu). Nevertheless, different relative cooling powers (RCP) of 112.6 J/kg (Sm) and 95.5 J/kg (Eu) were observed. A detailed analysis of the temperature-dependent lattice parameters shed light on a distinct magnetocaloric effect across the magnetic transition temperature, unveiling an anisotropic thermal expansion [αV = 1.41 × 10-5 K-1 (Sm) and αV = 1.54 × 10-5 K-1 (Eu)] wherein the thermal expansion axial ratio αbSm/αbEu = 0.61 became lower with increasing temperature, which suggests that the Eu sample experiences a greater thermal expansion in the b-axis direction. At the atomic bonding level, the evidence for magnetoelastic coupling around the magnetic transition temperatures TN was found through the anomalies along the average Co/Fe-O bond distance, formal valence, octahedral distortion, as well as an anisotropic lattice expansion.
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Affiliation(s)
- Romualdo S. Silva
- Instituto
de Ciencia de Materiales de Madrid (ICMM), CSIC, E-28049 Madrid, Spain
| | - João E. Rodrigues
- European
Synchrotron Radiation Facility (ESRF), 71 Avenue des Martyrs, 38000 Grenoble, France
- CELLS-ALBA
Synchrotron Light Source, Cerdanyola del Vallès, E-08290 Barcelona, Spain
| | - Javier Gainza
- Instituto
de Ciencia de Materiales de Madrid (ICMM), CSIC, E-28049 Madrid, Spain
| | | | - Lidia Martínez
- Instituto
de Ciencia de Materiales de Madrid (ICMM), CSIC, E-28049 Madrid, Spain
| | - Yves Huttel
- Instituto
de Ciencia de Materiales de Madrid (ICMM), CSIC, E-28049 Madrid, Spain
| | - José Luis Martínez
- Instituto
de Ciencia de Materiales de Madrid (ICMM), CSIC, E-28049 Madrid, Spain
| | - José Antonio Alonso
- Instituto
de Ciencia de Materiales de Madrid (ICMM), CSIC, E-28049 Madrid, Spain
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2
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Rodrigues JEFS, Gainza J, Serrano-Sánchez F, Silva RS, Dejoie C, Nemes NM, Dura OJ, Martínez JL, Alonso JA. Thermal Expansion and Rattling Behavior of Gd-Filled Co 4Sb 12 Skutterudite Determined by High-Resolution Synchrotron X-ray Diffraction. Materials (Basel) 2022; 16:370. [PMID: 36614710 PMCID: PMC9822039 DOI: 10.3390/ma16010370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 12/16/2022] [Accepted: 12/26/2022] [Indexed: 06/17/2023]
Abstract
In this work, Gd-filled skutterudite GdxCo4Sb12 was prepared using one step method under high pressure in a piston-cylinder-based press at 3.5 GPa and moderate temperature of 800 °C. A detailed structural characterization was performed using synchrotron X-ray diffraction (SXRD), revealing a filling fraction of x = 0.033(2) and an average <Gd−Sb> bond length of 3.3499(3) Å. The lattice thermal expansion accessed via temperature-dependent SXRD led to a precise determination of a Debye temperature of 322(3) K, from the fitting of the unit-cell volume expansion using the second order Grüneisen approximation. This parameter, when evaluated through the mean square displacements of Co and Sb, displayed a value of 265(2) K, meaning that the application of the harmonic Debye theory underestimates the Debye temperature in skutterudites. Regarding the Gd atom, its intrinsic disorder value was ~5× and ~25× higher than those of the Co and Sb, respectively, denoting that Gd has a strong rattling behavior with an Einstein temperature of θE = 67(2) K. As a result, an ultra-low thermal conductivity of 0.89 W/m·K at 773 K was obtained, leading to a thermoelectric efficiency zT of 0.5 at 673 K.
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Affiliation(s)
- João E. F. S. Rodrigues
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas, Sor Juana Inés de la Cruz 3, E-28049 Madrid, Spain
- European Synchrotron Radiation Facility (ESRF), 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Javier Gainza
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas, Sor Juana Inés de la Cruz 3, E-28049 Madrid, Spain
| | - Federico Serrano-Sánchez
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas, Sor Juana Inés de la Cruz 3, E-28049 Madrid, Spain
| | - Romualdo S. Silva
- Department of Physics, Federal University of Sergipe, São Cristóvão 49100-000, SE, Brazil
| | - Catherine Dejoie
- European Synchrotron Radiation Facility (ESRF), 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Norbert M. Nemes
- Departamento de Física de Materiales, Universidad Complutense de Madrid, E-28040 Madrid, Spain
| | - Oscar J. Dura
- Departamento de Física Aplicada, Universidad de Castilla-La Mancha, E-13071 Ciudad Real, Spain
| | - José L. Martínez
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas, Sor Juana Inés de la Cruz 3, E-28049 Madrid, Spain
| | - José Antonio Alonso
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas, Sor Juana Inés de la Cruz 3, E-28049 Madrid, Spain
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3
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Rodrigues JEFS, Gainza J, Serrano-Sánchez F, Nemes NM, Dura OJ, Martínez JL, Alonso JA. A novel crystallographic location of rattling atoms in filled Eu
x
Co 4Sb 12 skutterudites prepared under high-pressure conditions. Z KRIST-CRYST MATER 2022. [DOI: 10.1515/zkri-2022-0051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Abstract
Thermoelectric M
x
Co4Sb12 skutterudites are well-known to exhibit a reduced thermal conductivity thanks to the rattling effect of the M-filler at the large cages occurring in the framework, centered at the 2a sites of the
I
m
3
‾
$Im\overline{3}$
space group. A novel Eu-filled skutterudite has been synthesized under high-pressure conditions at 3.5 GPa in a piston-cylinder hydrostatic press. The structural refinement from high-angular resolution synchrotron X-ray diffraction (SXRD) patterns unveils an unusual position for Eu filler atoms. By difference Fourier synthesis they are found at 12d sites, conforming statistically occupied octahedra within the mentioned cages around 2a positions. The Debye temperature was estimated by averaging the isotropic displacements by the atomic masses, leading to
θ
D
${\theta }_{D}$
of 273(2) K. Oftedal plots concerning the y and z Sb fractional positions, the unit-cell parameter
a
and M filling fraction include the novel Eu specimen in the trend observed for other filled materials prepared under high-pressure, including rare-earths, alkali or alkali-earth elements, all accepted as rattlers in filled skutterudites. A total thermal conductivity (κ) of 0.82 W m−1 K−1 is measured at 773 K for Eu0.02(1)Co4Sb12, below that of other filled skutterudites, which is promoted by the enhanced phonon scattering of Eu located at 12d sites. FE-SEM images showed large, homogeneous grains, well compacted after the high-pressure synthesis.
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Affiliation(s)
- João Elias F. S. Rodrigues
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC) , Sor Juana Inés de la Cruz 3, E-28049 , Madrid , Spain
- European Synchrotron Radiation Facility (ESRF) , 71 Avenue des Martyrs, 38000 Grenoble , France
| | - Javier Gainza
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC) , Sor Juana Inés de la Cruz 3, E-28049 , Madrid , Spain
| | - Federico Serrano-Sánchez
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC) , Sor Juana Inés de la Cruz 3, E-28049 , Madrid , Spain
| | - Norbert M. Nemes
- Departamento de Física de Materiales , Universidad Complutense de Madrid , E-28040 Madrid , Spain
| | - Oscar J. Dura
- Departamento de Física Aplicada , Universidad de Castilla-La Mancha , Ciudad Real , E-13071 , Spain
| | - Jose Luis Martínez
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC) , Sor Juana Inés de la Cruz 3, E-28049 , Madrid , Spain
| | - Jose Antonio Alonso
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC) , Sor Juana Inés de la Cruz 3, E-28049 , Madrid , Spain
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4
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Gainza J, Serrano-Sánchez F, Dura OJ, Nemes NM, Martínez JL, Fernández-Díaz MT, Alonso JA. Reduced Thermal Conductivity in Nanostructured AgSbTe 2 Thermoelectric Material, Obtained by Arc-Melting. Nanomaterials (Basel) 2022; 12:3910. [PMID: 36364685 PMCID: PMC9653711 DOI: 10.3390/nano12213910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/02/2022] [Accepted: 11/04/2022] [Indexed: 06/16/2023]
Abstract
AgSbTe2 intermetallic compound is a promising thermoelectric material. It has also been described as necessary to obtain LAST and TAGS alloys, some of the best performing thermoelectrics of the last decades. Due to the random location of Ag and Sb atoms in the crystal structure, the electronic structure is highly influenced by the atomic ordering of these atoms and makes the accurate determination of the Ag/Sb occupancy of paramount importance. We report on the synthesis of polycrystalline AgSbTe2 by arc-melting, yielding nanostructured dense pellets. SEM images show a conspicuous layered nanostructuration, with a layer thickness of 25-30 nm. Neutron powder diffraction data show that AgSbTe2 crystalizes in the cubic Pm-3m space group, with a slight deficiency of Te, probably due to volatilization during the arc-melting process. The transport properties show some anomalies at ~600 K, which can be related to the onset temperature for atomic ordering. The average thermoelectric figure of merit remains around ~0.6 from ~550 up to ~680 K.
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Affiliation(s)
- Javier Gainza
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain
| | - Federico Serrano-Sánchez
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain
| | - Oscar J. Dura
- Departamento de Física Aplicada, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain
| | - Norbert M. Nemes
- Departamento de Física de Materiales, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Jose Luis Martínez
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain
| | | | - José Antonio Alonso
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain
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5
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López CA, Abia C, Rodrigues JE, Serrano-Sánchez F, Nemes NM, Martínez JL, Fernandez-Díaz MT, Biškup N, Alvarez-Galván C, Carrascoso F, Castellanos-Gomez A, Alonso JA. Author Correction: Enhanced stability in CH 3NH 3PbI 3 hybrid perovskite from mechano-chemical synthesis: structural, microstructural and optoelectronic characterization. Sci Rep 2022; 12:8416. [PMID: 35589953 PMCID: PMC9120503 DOI: 10.1038/s41598-022-12534-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Affiliation(s)
- Carlos A López
- Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049, Madrid, Spain. .,INTEQUI (CONICET‑UNSL), and Facultad de Química, Bioquímica y Farmacia, UNSL, 5700, Almirante Brown 1455, San Luis, Argentina.
| | - Carmen Abia
- Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049, Madrid, Spain.,Institut Laue Langevin, BP 156X, 38042, Grenoble, France
| | - Joao E Rodrigues
- Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049, Madrid, Spain
| | | | - Norbert M Nemes
- Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049, Madrid, Spain.,Departamento de Física de Materiales, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - José L Martínez
- Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049, Madrid, Spain
| | | | - Neven Biškup
- Departamento de Física de Materiales, Universidad Complutense de Madrid, 28040, Madrid, Spain.,Instituto Pluridisciplinar, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | | | - Felix Carrascoso
- Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049, Madrid, Spain
| | | | - José A Alonso
- Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049, Madrid, Spain.
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6
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Serrano-Sánchez F, Fernández-Díaz MT, Martínez JL, Alonso JA. On the magnetic structure and magnetic behaviour of the most distorted member of the series of RNiO 3 perovskites (R = Lu). Dalton Trans 2022; 51:2278-2286. [PMID: 35040857 DOI: 10.1039/d1dt03571a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The crystal structure of LuNiO3 perovskite has been examined below RT and across TN = 125 K by neutron powder diffraction. In this temperature region (2-298 K), well below the metal-insulator transition this oxide exhibits at TMI = 599 K, this material is insulating and characterized by a partial charge disproportionation of the Ni valence. In the perovskite structure, defined in the monoclinic P21/n space group, there are two inequivalent Ni sites located in alternating octahedra of different sizes. The structural analysis with high-resolution techniques (λ = 1.594 Å) unveils a subtle increase of the charge disproportionation as temperature decreases, reaching δeff = 0.34 at 2 K. The magnetic structure has been investigated from low-T NPD patterns collected with a larger wavelength (λ = 2.52 Å). Magnetic peaks are observed below TN; they can be indexed with a propagation vector k = (½, 0, ½), as previously observed in other RNiO3 perovskites for the Ni sublattice. Among the three possible solutions for the magnetic structure, the first one is discarded since it would correspond to a full charge ordering (Ni2+ + Ni4+), with magnetic moments only on Ni2+ ions, not compatible with the structural findings assessing a partial charge disproportionation. The best agreement is found for a non-collinear model with two different moments in Ni1 and Ni2 sites, 1.4(1) μB, and m 0.7(1) μB at 2 K, the ordered magnetic moments lying on the a-c plane. This is similar to that found for YNiO3. In complement, the magnetic and thermal properties of LuNiO3 have been investigated. AC susceptibility curves exhibit a clear peak centered at TN = 125 K, corresponding to the establishment of the Ni antiferromagnetic structure. This is corroborated by DC susceptibility and specific heat measurements. Magnetization vs. field measurements confirm that the system is antiferromagnetic down to 2 K, without any further magnetic change. This linear behavior is also observed in the paramagnetic regime (T > TN).
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Affiliation(s)
- Federico Serrano-Sánchez
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Sor Juana Inés de la Cruz 3, E-28049, Madrid, Spain.
| | | | - José Luis Martínez
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Sor Juana Inés de la Cruz 3, E-28049, Madrid, Spain.
| | - José Antonio Alonso
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Sor Juana Inés de la Cruz 3, E-28049, Madrid, Spain.
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7
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Figueiredo Soares Rodrigues JE, Gainza J, Serrano-Sánchez F, Ferrer M, Popescu C, Alonso J. Unveiling the structural behaviour under pressure of filled M
0.5Co 4Sb 12 ( M = K, Sr, La, Ce and Yb) thermoelectric skutterudites. Acta Crystallogr A Found Adv 2021. [DOI: 10.1107/s0108767321092308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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8
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Gainza J, Serrano-Sánchez F, Nemes NM, Dura OJ, Martínez JL, Fauth F, Alonso JA. Strongly reduced lattice thermal conductivity in Sn-doped rare-earth (M) filled skutterudites M x Co 4Sb 12-y Sn y , promoted by Sb-Sn disordering and phase segregation. RSC Adv 2021; 11:26421-26431. [PMID: 35479462 PMCID: PMC9037351 DOI: 10.1039/d1ra04270j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 07/26/2021] [Indexed: 11/21/2022] Open
Abstract
CoSb3 thermoelectric skutterudite has been filled with rare-earth metals (M = La, Ce, Yb) and partially doped with Sn in specimens of M x Co4Sb12-y Sn y stoichiometry. This has been achieved under high-pressure conditions at 3.5 GPa in a piston-cylinder hydrostatic press. A structural investigation using synchrotron X-ray diffraction data reveals a phase segregation in twin skutterudite phases with filling fraction fluctuation and different unit-cell sizes. As a result of three effects acting as phonon scatterers, namely the rattling effect of M at the wide 8a cages of the cubic Im3̄ structure, the phase segregation, and the intrinsic disorder introduced by Sn substitution at the Sb sublattice, the total thermal conductivity (κ) dramatically falls to reach minimum values under 2 W m-1 K-1, well below those typically exhibited by other thermoelectric materials based upon single-filled skutterudites. The power factor is substantially enhanced to 1.11 mW m-1 K-2 in Yb0.5Co4Sb11.6Sn0.4 with respect to the unfilled composition, as a result of the charge transfer promoted by the filler.
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Affiliation(s)
- J Gainza
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Sor Juana Inés de la Cruz 3 E-28049 Madrid Spain
| | - F Serrano-Sánchez
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Sor Juana Inés de la Cruz 3 E-28049 Madrid Spain
| | - N M Nemes
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Sor Juana Inés de la Cruz 3 E-28049 Madrid Spain
- Departamento de Física de Materiales, Universidad Complutense de Madrid E-28040 Madrid Spain
| | - O J Dura
- Departamento de Física Aplicada, Universidad de Castilla-La Mancha Ciudad Real E-13071 Spain
| | - J L Martínez
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Sor Juana Inés de la Cruz 3 E-28049 Madrid Spain
| | - F Fauth
- CELLS-ALBA Synchrotron Cerdanyola del Valles Barcelona E-08290 Spain
| | - J A Alonso
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Sor Juana Inés de la Cruz 3 E-28049 Madrid Spain
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9
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Rodrigues JEFS, Gainza J, Serrano-Sánchez F, Ferrer MM, Fabris GSL, Sambrano JR, Nemes NM, Martínez JL, Popescu C, Alonso JA. Unveiling the Structural Behavior under Pressure of Filled M 0.5Co 4Sb 12 (M = K, Sr, La, Ce, and Yb) Thermoelectric Skutterudites. Inorg Chem 2021; 60:7413-7421. [PMID: 33900757 PMCID: PMC8414478 DOI: 10.1021/acs.inorgchem.1c00682] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Skutterudite-type
compounds based on □Co4Sb12 pnictide
are promising for thermoelectric application due
to their good Seebeck values and high carrier mobility. Filling the
8a voids (in the cubic space group Im3̅) with different elements (alkali, alkali earth, and rare
earth) helps to reduce the thermal conductivity and thus increases
the thermoelectric performance. A systematic characterization by synchrotron
X-ray powder diffraction of different M-filled Co4Sb12 (M = K, Sr, La, Ce, and Yb) skutterudites was carried out
under high pressure in the range ∼0–12 GPa. The isothermal
equations of state (EOS) were obtained in this pressure range and
the Bulk moduli (B0) were calculated for
all the filled skutterudites, yielding unexpected results. A lattice
expansion due to the filler elements fails in the description of the
Bulk moduli. Topochemical studies of the filler site environment exhibited
a slight disturbance and an increased ionic character when the filler
is incorporated. The mechanical properties by means of Bulk moduli
resulted in being sensitive to the presence of filler atoms inside
the skutterudite voids, being affected by the covalent/ionic exchange
of the Co–Sb and Sb–Sb bonds. High-pressure studies in the range ∼0−12
GPa
were carried out for M-filled Co4Sb12 (M = K,
Sr, La, Ce, and Yb) skutterudites. The isothermal equations of state
(EOS) were obtained and the Bulk moduli (B0) were calculated, yielding unexpected results. Topochemical studies
of the filler site environment exhibited a slight disturbance and
an increased ionic character when the filler is incorporated. (left)
3D structure and (right) Laplacian of electronic density isolines
of the M−Sb and Sb−Sb interactions.
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Affiliation(s)
- João Elias F S Rodrigues
- Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, E-28049 Madrid, Spain.,European Synchrotron Radiation Facility, ESRF, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Javier Gainza
- Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, E-28049 Madrid, Spain
| | | | - Mateus M Ferrer
- CCAF, PPGCEM/CDTec, Federal University of Pelotas, CEP 96010-610 Pelotas, Rio Grande do Sul, Brazil
| | - Guilherme S L Fabris
- Materials Science and Engineering Postgraduate Program, Department of Materials Engineering, Federal University of Rio Grande do Norte, 59078-970 Natal, Brazil
| | - Julio R Sambrano
- Modeling and Molecular Simulation Group, São Paulo State University, 17030-360 Bauru, SP, Brazil
| | - Norbert M Nemes
- Departamento de Física de Materiales, Universidad Complutense de Madrid, E-28040 Madrid, Spain
| | - José L Martínez
- Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, E-28049 Madrid, Spain
| | - Catalin Popescu
- CELLS-ALBA Synchrotron, E-08290 Cerdanyola del Valles, Barcelona, Spain
| | - José A Alonso
- Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, E-28049 Madrid, Spain
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10
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Serrano-Sánchez F, Martínez JL, Fauth F, Alonso JA. On the lack of monoclinic distortion in the insulating regime of EuNiO 3 and GdNiO 3 perovskites by high-angular resolution synchrotron X-ray diffraction: a comparison with YNiO 3. Dalton Trans 2021; 50:7085-7093. [PMID: 33949539 DOI: 10.1039/d1dt00646k] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Rare-earth nickelates RNiO3 (R = Y, LaLu) are electron-correlated perovskite materials where the interplay between charge and spin order results in a rich phase diagram, evolving from antiferromagnetic insulators to paramagnetic metals. They are well-known to undergo metal-insulator (MI) transitions as a function of temperature and the size of the rare-earth ion. For intermediate-size Eu3+ and Gd3+ ions, the MI transitions are described to happen at TMI = 463 K and 511 K, respectively. We have investigated their structural evolution across TMI with the excellent angular resolution of synchrotron X-ray diffraction, using high-crystalline quality samples prepared at elevated hydrostatic pressures. Unlike YNiO3, synthesized and measured under the same conditions, exhibiting a characteristic monoclinic phase (space group P21/n) in the insulating regime (below TMI), the present EuNiO3 and GdNiO3 samples do not exhibit such a symmetry, but their crystal structures can be defined in an orthorhombic superstructure of perovskite (space group Pbnm) in all the temperature interval, between 100 and 623 K for Eu and 298 K and 650 K for Gd. Nevertheless, an abrupt evolution of the unit-cell parameters is observed upon metallization above TMI. A prior report of a charge disproportionation effect by Mössbauer spectroscopy on Fe-doped perovskite samples seems to suggest that the distribution of two distinct Ni sites must not exhibit the required long-range ordering to be effectively detected by diffraction methods. An abrupt contraction of the b parameter of EuNiO3 in the 175-200 K range, coincident with the onset of antiferromagnetic ordering, suggests a magnetoelastic coupling, not described so far in rare-earth nickelates. The magnetic susceptibility is dominated by the paramagnetic signal of the rare-earth ions; however, the AC susceptibility curves yield a Néel temperature corresponding to the antiferromagnetic ordering of the Ni moments of TN = 197 K for EuNiO3, corroborated by specific heat measurements. For GdNiO3, a χT vs. T plot presents a clear change in the slope at TN = 187 K, also consistent with specific heat data. Magnetization measurements at 2 K under large fields up to 14 T show a complete saturation of the magnetic moments with a rather high ordered moment of 7.5μB per f.u.
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Affiliation(s)
- Federico Serrano-Sánchez
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Sor Juana Inés de la Cruz 3, E-28049, Madrid, Spain.
| | - José Luis Martínez
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Sor Juana Inés de la Cruz 3, E-28049, Madrid, Spain.
| | - François Fauth
- CELLS-ALBA Synchrotron, Cerdanyola del Valles, Barcelona, E-08290, Spain
| | - José Antonio Alonso
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Sor Juana Inés de la Cruz 3, E-28049, Madrid, Spain.
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11
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Rodrigues JEFS, Gainza J, Serrano-Sánchez F, López C, Dura OJ, Nemes N, Martinez JL, Huttel Y, Fauth F, Fernández-Diaz MT, Biškup N, Alonso JA. Structural Features, Anisotropic Thermal Expansion, and Thermoelectric Performance in Bulk Black Phosphorus Synthesized under High Pressure. Inorg Chem 2020; 59:14932-14943. [PMID: 33006896 DOI: 10.1021/acs.inorgchem.0c01573] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Black phosphorus (BP) allotrope has an orthorhombic crystal structure with a narrow bandgap of 0.35 eV. This material is promising for 2D technology since it can be exfoliated down to one single layer: the well-known phosphorene. In this work, bulk BP was synthesized under high-pressure conditions at high temperatures. A detailed structural investigation using neutron and synchrotron X-ray diffraction revealed the occurrence of anisotropic strain effects on the BP lattice; the combination of both sets of diffraction data allowed visualization of the lone electron pair 3s2. Temperature-dependent neutron diffraction data collected at low temperature showed that the a axis (zigzag) exhibits a quasi-temperature-independent thermal expansion in the temperature interval from 20 up to 150 K. These results may be a key to address the anomalous behavior in electrical resistivity near 150 K. Thermoelectric properties were also provided; low thermal conductivity from 14 down to 6 Wm-1K-1 in the range 323-673 K was recorded in our polycrystalline BP, which is below the reported values for single-crystals in literature.
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Affiliation(s)
| | - Javier Gainza
- Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, E-28049 Madrid, Spain
| | | | - Carlos López
- INTEQUI, (UNSL-CONICET), and Fac. de Química, Bioquímica y Farmacia, UNSL, Almirante Brown 1455, 5700, San Luis (SL), Argentina
| | - Oscar J Dura
- Departamento de Física Aplicada, Universidad de Castilla-La Mancha, E-13071 Ciudad Real, Spain
| | - Norbert Nemes
- Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, E-28049 Madrid, Spain.,Departamento de Física de Materiales, Universidad Complutense de Madrid, E-28040 Madrid, Spain
| | - Jose L Martinez
- Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, E-28049 Madrid, Spain
| | - Yves Huttel
- Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, E-28049 Madrid, Spain
| | - Francois Fauth
- CELLS-ALBA Synchrotron, E-08290 Cerdanyola del Valles, Barcelona, Spain
| | | | - Nevenko Biškup
- Departamento de Física de Materiales, Universidad Complutense de Madrid, E-28040 Madrid, Spain.,Instituto Pluridisciplinar, Universidad Complutense de Madrid, E-28040 Madrid, Spain
| | - José Antonio Alonso
- Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, E-28049 Madrid, Spain
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12
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López CA, Abia C, Alvarez-Galván MC, Hong BK, Martínez-Huerta MV, Serrano-Sánchez F, Carrascoso F, Castellanos-Gómez A, Fernández-Díaz MT, Alonso JA. Crystal Structure Features of CsPbBr 3 Perovskite Prepared by Mechanochemical Synthesis. ACS Omega 2020; 5:5931-5938. [PMID: 32226873 PMCID: PMC7098001 DOI: 10.1021/acsomega.9b04248] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 02/03/2020] [Indexed: 05/04/2023]
Abstract
We present a mechanochemical procedure, with solvent-free, green-chemistry credentials, to grow all-inorganic CsPbBr3 perovskite. The crystal structure of this perovskite and its correlations with the physicochemical properties have been studied. Synchrotron X-ray diffraction (SXRD) and neutron powder diffraction (NPD) allowed us to follow the crystallographic behavior from 4 to 773 K. Unreported features like the observed negative thermal expansion of the b unit-cell parameter stem from octahedral distortions in the 4-100 K temperature range. The mechanochemical synthesis was designed to reduce the impact energy during the milling process, leading to a defect-free, well-crystallized sample characterized by a minimum unit-cell volume and octahedral tilting angles in the low-temperature orthorhombic perovskite framework, defined in the Pbnm space group. The UV-vis diffuse reflectance spectrum shows a reduced band gap of 2.22(3) eV, and the photocurrent characterization in a photodetector reveals excellent properties with potential applications of this material in optoelectronic devices.
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Affiliation(s)
- Carlos A. López
- Instituto
de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid, Spain
- INTEQUI,
(UNSL-CONICET) and Facultad de Química, Bioquímica y
Farmacia, UNSL, Almirante Brown 1455, 5700 San Luis, Argentina
- E-mail: ,
(C.A.L.)
| | - Carmen Abia
- Instituto
de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid, Spain
- Institut
Laue Langevin, 38042 Grenoble Cedex, France
| | | | - Bo-Kyung Hong
- Instituto
de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid, Spain
- Instituto
de Catálisis y Petroleoquímica, CSIC, Cantoblanco, 28049 Madrid, Spain
| | | | | | - Felix Carrascoso
- Instituto
de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid, Spain
| | | | | | - José A. Alonso
- Instituto
de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid, Spain
- E-mail: (J.A.A.)
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13
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Gainza J, Serrano-Sánchez F, Biskup N, Nemes NM, Martínez JL, Fernández-Díaz MT, Alonso JA. Influence of Nanostructuration on PbTe Alloys Synthesized by Arc-Melting. Materials (Basel) 2019; 12:E3783. [PMID: 31752118 PMCID: PMC6888120 DOI: 10.3390/ma12223783] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 11/13/2019] [Accepted: 11/14/2019] [Indexed: 12/03/2022]
Abstract
PbTe-based alloys have the best thermoelectric properties for intermediate temperature applications (500-900 K). We report on the preparation of pristine PbTe and two doped derivatives (Pb0.99Sb0.01Te and Ag0.05Sb0.05Pb0.9Te, so-called LAST18) by a fast arc-melting technique, yielding nanostructured polycrystalline pellets. XRD and neutron powder diffraction (NPD) data assessed the a slight Te deficiency for PbTe, also yielding trends on the displacement factors of the 4a and 4b sites of the cubic Fm-3m space group. Interestingly, SEM analysis shows the conspicuous formation of layers assembled as stackings of nano-sheets, with 20-30 nm thickness. TEM analysis shows intra-sheet nanostructuration on the 50 nm scale in the form of polycrystalline grains. Large numbers of grain boundaries are created by this nanostructuration and this may contribute to reduce the thermal conductivity to a record-low value of 1.6 Wm-1K-1 at room temperature. In LAST18, a positive Seebeck coefficient up to 600 μV K-1 at 450 K was observed, contributing further towards improving potential thermoelectric efficiency.
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Affiliation(s)
- Javier Gainza
- Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco, E-28049 Madrid, Spain; (F.S.-S.); (J.L.M.); (J.A.A.)
- Departamento de Física de Materiales, Universidad Complutense de Madrid, E-28040 Madrid, Spain; (N.B.); (N.M.N.)
| | - Federico Serrano-Sánchez
- Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco, E-28049 Madrid, Spain; (F.S.-S.); (J.L.M.); (J.A.A.)
| | - Neven Biskup
- Departamento de Física de Materiales, Universidad Complutense de Madrid, E-28040 Madrid, Spain; (N.B.); (N.M.N.)
- Instituto Pluridisciplinar, Universidad Complutense de Madrid, E-28040 Madrid, Spain
| | - Norbert Marcel Nemes
- Departamento de Física de Materiales, Universidad Complutense de Madrid, E-28040 Madrid, Spain; (N.B.); (N.M.N.)
| | - José Luis Martínez
- Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco, E-28049 Madrid, Spain; (F.S.-S.); (J.L.M.); (J.A.A.)
| | | | - José Antonio Alonso
- Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco, E-28049 Madrid, Spain; (F.S.-S.); (J.L.M.); (J.A.A.)
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14
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Serrano-Sánchez F, Fauth F, Martínez JL, Alonso JA. Experimental Observation of Monoclinic Distortion in the Insulating Regime of SmNiO3 by Synchrotron X-ray Diffraction. Inorg Chem 2019; 58:11828-11835. [DOI: 10.1021/acs.inorgchem.9b02013] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Federico Serrano-Sánchez
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Sor Juana Inés de la Cruz 3, E-28049, Madrid, Spain
| | - François Fauth
- CELLS−ALBA Synchrotron, Cerdanyola del Valles, E-08290 Barcelona, Spain
| | - José Luis Martínez
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Sor Juana Inés de la Cruz 3, E-28049, Madrid, Spain
| | - José Antonio Alonso
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Sor Juana Inés de la Cruz 3, E-28049, Madrid, Spain
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15
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Serrano-Sánchez F, Nemes NM, Martínez JL, Juan-Dura O, de la Torre MA, Fernández-Díaz MT, Alonso JA. Structural evolution of a Ge-substituted SnSe thermoelectric material with low thermal conductivity. J Appl Crystallogr 2018. [DOI: 10.1107/s1600576718000808] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Thermoelectric materials are expected to become new alternative sources of sustainable energy. Among them, the SnSe intermetallic alloy has been described as an excellent thermoelectric compound, characterized by an extremely low thermal conductivity with maximum performance at the onset of a structural phase transition at 800 K. Recently, novel SnSe derivatives with Ge substitution have been synthesized by a direct arc-melting technique. This produces nanostructured polycrystalline samples that exhibit a record high Seebeck coefficient, anticipating an excellent performance above room temperature. Here, the structural phase transition from a GeS-type structure (space groupPnma) to a TlI-type structure (space groupCmcm) is investigatedin situ vianeutron powder diffraction (NPD) in the temperature range 298–853 K for the selected composition Sn0.8Ge0.2Se. This transition takes place at 803 K, as shown by differential scanning calorimetry. The analysis from the NPD data shows a non-monotonic behaviour of the anisotropic displacement parameters upon entering the domain of theCmcmstructure. The energies of the atomic vibrations have been quantitatively analysed by fitting the temperature-dependent mean-square displacements to Einstein oscillators. The thermal conductivity of Sn0.8Ge0.2Se is as low as 0.35 W m−1 K−1at 773 K, which mostly represents the lattice thermal contribution.
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16
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Gharsallah M, Serrano-Sánchez F, Bermúdez J, Nemes NM, Martínez JL, Elhalouani F, Alonso JA. Nanostructured Bi2Te3 Prepared by a Straightforward Arc-Melting Method. Nanoscale Res Lett 2016; 11:142. [PMID: 26976428 PMCID: PMC4791409 DOI: 10.1186/s11671-016-1345-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 02/27/2016] [Indexed: 06/04/2023]
Abstract
Thermoelectric materials constitute an alternative source of sustainable energy, harvested from waste heat. Bi2Te3 is the most utilized thermoelectric alloy. We show that it can be readily prepared in nanostructured form by arc-melting synthesis, yielding mechanically robust pellets of highly oriented polycrystals. This material has been characterized by neutron powder diffraction (NPD), scanning electron microscopy (SEM), and electronic and thermal transport measurements. A microscopic analysis from NPD data demonstrates a near-perfect stoichiometry of Bi2Te3 and a fair amount of anharmonicity of the chemical bonds. The as-grown material presents a metallic behavior, showing a record-low resistivity at 320 K of 2 μΩ m, which is advantageous for its performance as a thermoelectric material. SEM analysis shows a stacking of nanosized sheets, each of them presumably single-crystalline, with large surfaces perpendicular to the c crystallographic axis. This nanostructuration notably affects the thermoelectric properties, involving many surface boundaries that are responsible for large phonon scattering factors, yielding a thermal conductivity as low as 1.2 W m(-1) K(-1) around room temperature.
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Affiliation(s)
- M Gharsallah
- Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco, E-28049, Madrid, Spain
- National School of Engineers, Sfax University, Sfax, B. P. W 3038, Tunisia
| | - F Serrano-Sánchez
- Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco, E-28049, Madrid, Spain
| | - J Bermúdez
- Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco, E-28049, Madrid, Spain
| | - N M Nemes
- Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco, E-28049, Madrid, Spain
| | - J L Martínez
- Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco, E-28049, Madrid, Spain
| | - F Elhalouani
- National School of Engineers, Sfax University, Sfax, B. P. W 3038, Tunisia
| | - J A Alonso
- Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco, E-28049, Madrid, Spain.
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17
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Serrano-Sánchez F, Nemes NM, Dura OJ, Fernandez-Diaz MT, Martínez JL, Alonso JA. Structural phase transition in polycrystalline SnSe: a neutron diffraction study in correlation with thermoelectric properties. J Appl Crystallogr 2016. [DOI: 10.1107/s1600576716015405] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
SnSe has been recently reported as a promising and highly efficient thermoelectric intermetallic alloy. The present material has been prepared by arc melting, as mechanically robust pellets, consisting of highly oriented polycrystals. The evolution of its orthorhombic GeS-type structure (space groupPnma) and phase transition to TlI-type structure (space groupCmcm) at high temperature has been studiedin situby neutron powder diffraction (NPD) in the temperature range 295–873 K. This transition has been identified by differential scanning calorimetry measurements, yielding sharp peaks at 795 K. In addition, thermal transport properties were measured in a similar temperature range, and large Seebeck coefficients, as high as 1050 µV K−1at 625 K, were found. The analysis from NPD data demonstrates an almost perfect stoichiometry, Sn0.998(8)Se, that does not evolve with temperature, and a progressive decrease of the anharmonicity of the chemical bonds upon entering the domain of theCmcmstructure.
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18
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Gharsallah M, Serrano-Sánchez F, Nemes NM, Mompeán FJ, Martínez JL, Fernández-Díaz MT, Elhalouani F, Alonso JA. Giant Seebeck effect in Ge-doped SnSe. Sci Rep 2016; 6:26774. [PMID: 27251233 PMCID: PMC4890000 DOI: 10.1038/srep26774] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 05/06/2016] [Indexed: 11/09/2022] Open
Abstract
Thermoelectric materials may contribute in the near future as new alternative sources of sustainable energy. Unprecedented thermoelectric properties in p-type SnSe single crystals have been recently reported, accompanied by extremely low thermal conductivity in polycrystalline samples. In order to enhance thermoelectric efficiency through proper tuning of this material we report a full structural characterization and evaluation of the thermoelectric properties of novel Ge-doped SnSe prepared by a straightforward arc-melting method, which yields nanostructured polycrystalline samples. Ge does not dope the system in the sense of donating carriers, yet the electrical properties show a semiconductor behavior with resistivity values higher than that of the parent compound, as a consequence of nanostructuration, whereas the Seebeck coefficient is higher and thermal conductivity lower, favorable to a better ZT figure of merit.
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Affiliation(s)
- M Gharsallah
- Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco, E-28049 Madrid, Spain.,Sfax University, National School of Engineers, B. P. W 3038, Tunisia
| | - F Serrano-Sánchez
- Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco, E-28049 Madrid, Spain
| | - N M Nemes
- Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco, E-28049 Madrid, Spain
| | - F J Mompeán
- Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco, E-28049 Madrid, Spain
| | - J L Martínez
- Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco, E-28049 Madrid, Spain
| | | | - F Elhalouani
- Sfax University, National School of Engineers, B. P. W 3038, Tunisia
| | - J A Alonso
- Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco, E-28049 Madrid, Spain
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