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Chen GR, Wang MF, Lee CS. Synthesis and characterization of new multinary selenides Sn4In5Sb9Se25 and Sn6.13Pb1.87In5.00Sb10.12Bi2.88Se35. J SOLID STATE CHEM 2022. [DOI: 10.1016/j.jssc.2021.122855] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Nakayama K, Souma S, Trang CX, Takane D, Chen C, Avila J, Takahashi T, Sasaki S, Segawa K, Asensio MC, Ando Y, Sato T. Nanomosaic of Topological Dirac States on the Surface of Pb 5Bi 24Se 41 Observed by Nano-ARPES. NANO LETTERS 2019; 19:3737-3742. [PMID: 31038974 DOI: 10.1021/acs.nanolett.9b00875] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We have performed scanning angle-resolved photoemission spectroscopy with a nanometer-sized beam spot (nano-ARPES) on the cleaved surface of Pb5Bi24Se41, which is a member of the (PbSe)5(Bi2Se3)3 m homologous series (PSBS) with m = 4 consisting of alternate stacking of the topologically trivial insulator PbSe bilayer and four quintuple layers (QLs) of the topological insulator Bi2Se3. This allows us to visualize a mosaic of topological Dirac states at a nanometer scale coming from the variable thickness of the Bi2Se3 nanoislands (1-3 QLs) that remain on top of the PbSe layer after cleaving the PSBS crystal, because the local band structure of topological origin changes drastically with the thickness of the Bi2Se3 nanoislands. A comparison of the local band structure with that in ultrathin Bi2Se3 films on Si(111) gives us further insights into the nature of the observed topological states. This result demonstrates that nano-ARPES is a very useful tool for characterizing topological heterostructures.
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Affiliation(s)
- Kosuke Nakayama
- Department of Physics , Tohoku University , Sendai 980-8578 , Japan
| | | | - Chi Xuan Trang
- Department of Physics , Tohoku University , Sendai 980-8578 , Japan
| | - Daichi Takane
- Department of Physics , Tohoku University , Sendai 980-8578 , Japan
| | - Chaoyu Chen
- Synchrotron SOLEIL , L'Orme des Merisiers , Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cédex , France
| | - Jose Avila
- Synchrotron SOLEIL , L'Orme des Merisiers , Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cédex , France
| | | | - Satoshi Sasaki
- School of Physics and Astronomy , University of Leeds , Leeds LS2 9JT , United Kingdom
| | - Kouji Segawa
- Department of Physics , Kyoto Sangyo University , Kyoto 603-8555 , Japan
| | - Maria Carmen Asensio
- Instituto de Ciencia de Materiales de Madrid (ICMM) , CSIC, Cantoblanco , 28049 Madrid Spain
| | - Yoichi Ando
- Physics Institute II , University of Cologne , 50937 Köln , Germany
| | - Takafumi Sato
- Department of Physics , Tohoku University , Sendai 980-8578 , Japan
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Sassi S, Candolfi C, Dauscher A, Lenoir B, Koza MM. Inelastic neutron scattering study of the lattice dynamics of the homologous compounds (PbSe) 5(Bi 2Se 3) 3m (m = 1, 2 and 3). Phys Chem Chem Phys 2018; 20:14597-14607. [PMID: 29766168 DOI: 10.1039/c8cp01277f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report on the inelastic response of the homologous compounds (PbSe)5(Bi2Se3)3m for m = 1, 2 and 3 followed in a broad temperature range (50-500 K) using high-resolution powder inelastic neutron scattering experiments. These results are complemented by low-temperature measurements of the specific heat (2-300 K). The evolution of the anisotropic crystal structure of these compounds with varying m, built from alternate Pb-Se and mBi-Se layers, only weakly influences the generalized phonon density of states. In all the three compounds, intense inelastic signals, likely mainly associated with the dynamics of the Pb atoms, are observed in the 4.5-6 meV low-energy range. The response of these low-energy modes to temperature variations indicates a conventional quasi-harmonic behavior over the whole temperature range investigated. The modes located above 8 meV show a minor temperature effect regardless of the value of m. The low-energy excess of vibrational modes manifests itself in the low-temperature specific heat as a pronounced peak in the Cp(T)/T3 data near 10 K. The lack of significant anharmonicity beyond that associated with the thermal expansion of the lattice suggests that the inherent disorder in the monoclinic unit cell and scattering at interlayer interfaces are the most important ingredients that limit the heat transport in this series of compounds.
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Affiliation(s)
- Selma Sassi
- Institut Jean Lamour, UMR 7198 CNRS, Université de Lorraine, 2 allée André Guinier-Campus ARTEM, BP 50840, 54011 Nancy Cedex, France.
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Sassi S, Candolfi C, Gendarme C, Dauscher A, Lenoir B. Synthesis and transport properties of the Te-substituted homologous compounds Pb 5Bi 6Se 14-xTe x (0 ≤ x ≤ 1.0). Dalton Trans 2018. [PMID: 29537002 DOI: 10.1039/c7dt04916a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The crystal structure and transport properties (2-723 K) of the homologous compound Pb5Bi6Se14 with partial substitution of Te for Se are studied by means of powder X-ray diffraction, scanning electron microscopy, electrical resistivity, thermopower, thermal conductivity and Hall effect measurements. Polycrystalline samples of Pb5Bi6Se14-xTex (0 ≤ x ≤ 1.0) were prepared by a two-step synthesis method based on the pseudo-binary PbSe-Bi2Se3 phase diagram combined with Te substitution in the PbSe precursor. The successful insertion of Te into the crystal structure of Pb5Bi6Se14 was confirmed by powder X-ray diffraction and scanning electron microscopy. Transport property measurements indicate an increase in the heavily doped character of the transport with increasing the Te concentration. The extremely low lattice thermal conductivity values (0.3-0.4 W m-1 K-1 at 723 K) that approach the glassy limit at high temperatures are nearly independent of the chemical composition suggesting no influence on point-defect scattering mechanisms in the substituted compounds. Despite the inherent complexity of this system, the evolution of the electronic properties with x is well described by a simple single-parabolic band model. Because the increase in the power factor with increasing x is compensated by the concomitant increase in the electronic thermal conductivity, this substitution does not yield enhanced ZT values with respect to the pristine compound with a similar peak ZT value of 0.5 achieved at 723 K. Nevertheless, the simple synthetic method used in this study to insert a doping element opens new avenues for controlling the transport properties of the homologous series (PbSe)5(Bi2Se3)3m (m = 1, 2 and 3).
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Affiliation(s)
- Selma Sassi
- Institut Jean Lamour, UMR 7198 CNRS - Université de Lorraine, 2 allée André Guinier-Campus ARTEM, BP 50840, 54011 Nancy Cedex, France.
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Sassi S, Candolfi C, Delaizir G, Migot S, Ghanbaja J, Gendarme C, Dauscher A, Malaman B, Lenoir B. Crystal Structure and Transport Properties of the Homologous Compounds (PbSe) 5(Bi 2Se 3) 3m (m = 2, 3). Inorg Chem 2017; 57:422-434. [PMID: 29257669 DOI: 10.1021/acs.inorgchem.7b02656] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report on a detailed investigation of the crystal structure and transport properties in a broad temperature range (2-723 K) of the homologous compounds (PbSe)5(Bi2Se3)3m for m = 2, 3. Single-crystal X-ray diffraction data indicate that the m = 2, 3 compounds crystallize in the monoclinic space groups C2/m (No. 12) and P21/m (No. 11), respectively. In agreement with diffraction data, high-resolution transmission electron microscopy analyses carried out on single crystals show that the three-dimensional crystal structures are built from alternating Pb-Se and m Bi-Se layers stacked along the a axis in both compounds. Scanning electron microcopy and electron-probe microanalyses reveal deviations from the nominal stoichiometry, suggesting a domain of existence in the pseudo binary phase diagram at 873 K. The complex atomic-scale structures of these compounds lead to very low lattice thermal conductivities κL that approach the glassy limit at high temperatures. A comparison of the κL values across this series unveiled an unexpected increase with increasing m from m = 1 to m = 3, in contrast to the expectation that increasing the structural complexity should tend to lower the thermal transport. This result points to a decisive role played by the Pb-Se/Bi-Se interfaces in limiting κL in this series. Both compounds behave as heavily doped n-type semiconductors with relatively low electrical resistivity and thermopower values. As a result, moderate peak ZT values of 0.25 and 0.20 at 700 K were achieved in the m = 2, 3 compounds, respectively. The inherent poor ability of these structures to conduct heat suggests that these homologous compounds may show interesting thermoelectric properties when properly optimized by extrinsic dopants.
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Affiliation(s)
- Selma Sassi
- Institut Jean Lamour, UMR 7198 CNRS-Université de Lorraine , 2 allée André Guinier-Campus ARTEM, 54011 Nancy, France
| | - Christophe Candolfi
- Institut Jean Lamour, UMR 7198 CNRS-Université de Lorraine , 2 allée André Guinier-Campus ARTEM, 54011 Nancy, France
| | - Gaëlle Delaizir
- Sciences des Procédés Céramique et de Traitement de Surface (SPCTS), UMR CNRS 7315-Univsersité de Limoges , Limoges, France
| | - Sylvie Migot
- Institut Jean Lamour, UMR 7198 CNRS-Université de Lorraine , 2 allée André Guinier-Campus ARTEM, 54011 Nancy, France
| | - Jaafar Ghanbaja
- Institut Jean Lamour, UMR 7198 CNRS-Université de Lorraine , 2 allée André Guinier-Campus ARTEM, 54011 Nancy, France
| | - Christine Gendarme
- Institut Jean Lamour, UMR 7198 CNRS-Université de Lorraine , 2 allée André Guinier-Campus ARTEM, 54011 Nancy, France
| | - Anne Dauscher
- Institut Jean Lamour, UMR 7198 CNRS-Université de Lorraine , 2 allée André Guinier-Campus ARTEM, 54011 Nancy, France
| | - Bernard Malaman
- Institut Jean Lamour, UMR 7198 CNRS-Université de Lorraine , 2 allée André Guinier-Campus ARTEM, 54011 Nancy, France
| | - Bertrand Lenoir
- Institut Jean Lamour, UMR 7198 CNRS-Université de Lorraine , 2 allée André Guinier-Campus ARTEM, 54011 Nancy, France
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Sato M, Ando Y. Topological superconductors: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:076501. [PMID: 28367833 DOI: 10.1088/1361-6633/aa6ac7] [Citation(s) in RCA: 258] [Impact Index Per Article: 36.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
This review elaborates pedagogically on the fundamental concept, basic theory, expected properties, and materials realizations of topological superconductors. The relation between topological superconductivity and Majorana fermions are explained, and the difference between dispersive Majorana fermions and a localized Majorana zero mode is emphasized. A variety of routes to topological superconductivity are explained with an emphasis on the roles of spin-orbit coupling. Present experimental situations and possible signatures of topological superconductivity are summarized with an emphasis on intrinsic topological superconductors.
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Affiliation(s)
- Masatoshi Sato
- Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502, Japan
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Jood P, Ohta M. Hierarchical Architecturing for Layered Thermoelectric Sulfides and Chalcogenides. MATERIALS 2015; 8:1124-1149. [PMID: 28787992 PMCID: PMC5455437 DOI: 10.3390/ma8031124] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 02/25/2015] [Accepted: 02/26/2015] [Indexed: 11/16/2022]
Abstract
Sulfides are promising candidates for environment-friendly and cost-effective thermoelectric materials. In this article, we review the recent progress in all-length-scale hierarchical architecturing for sulfides and chalcogenides, highlighting the key strategies used to enhance their thermoelectric performance. We primarily focus on TiS2-based layered sulfides, misfit layered sulfides, homologous chalcogenides, accordion-like layered Sn chalcogenides, and thermoelectric minerals. CS2 sulfurization is an appropriate method for preparing sulfide thermoelectric materials. At the atomic scale, the intercalation of guest atoms/layers into host crystal layers, crystal-structural evolution enabled by the homologous series, and low-energy atomic vibration effectively scatter phonons, resulting in a reduced lattice thermal conductivity. At the nanoscale, stacking faults further reduce the lattice thermal conductivity. At the microscale, the highly oriented microtexture allows high carrier mobility in the in-plane direction, leading to a high thermoelectric power factor.
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Affiliation(s)
- Priyanka Jood
- Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan.
| | - Michihiro Ohta
- Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan.
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