1
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Ni C, O'Connor KM, Butler C, Veinot JGC. Synthesis of high-entropy germanides and investigation of their formation process. NANOSCALE HORIZONS 2024; 9:580-588. [PMID: 38446210 DOI: 10.1039/d4nh00012a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/07/2024]
Abstract
High-entropy alloys and compounds have emerged as an attractive research area in part because of their distinctive solid-solution structure and multi-element compositions that provide near-limitless tailorability. A diverse array of reports describing high-entropy compounds, including carbides, nitrides, sulfides, oxides, fluorides, silicides, and borides, has resulted. Strikingly, exploration of high-entropy germanides (HEGs) has remained relatively limited. In this study, we present a detailed investigation into the synthesis of HEGs, specifically AuAgCuPdPtGe and FeCoNiCrVGe, via a rapid thermal annealing. The structural, compositional, and morphological characteristics of the synthesized HEGs were assessed using laboratory X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Complementing these post-synthesis analyses, we interrogated the formation and growth mechanisms using in situ heating XRD and TEM and determined that HEG formation involved initial decomposition of germanane (GeNSs) during the annealing, followed by gradual grain growth via atom diffusion at temperatures below 600 °C, and finally a rapid grain growth process at elevated temperatures.
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Affiliation(s)
- Chuyi Ni
- Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2, Canada.
| | - Kevin M O'Connor
- Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2, Canada.
| | - Cole Butler
- Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2, Canada.
| | - Jonathan G C Veinot
- Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2, Canada.
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2
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Wei S, Qin N, Wu G, Xu Z, Miao L, Chen X, Yan J. Thermoelectric Properties of Zn-Doped YbMg 1.85-xZn xBi 1.98. MATERIALS (BASEL, SWITZERLAND) 2024; 17:973. [PMID: 38473446 DOI: 10.3390/ma17050973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 02/13/2024] [Accepted: 02/17/2024] [Indexed: 03/14/2024]
Abstract
Bi-based YbMg2Bi1.98 Zintl compounds represent promising thermoelectric materials. Precise composition and appropriate doping are of great importance for this complex semiconductor. Here, the influence of Zn substitution for Mg on the microstructure and thermoelectric properties of p-type YbMg1.85-xZnxBi1.98 (x = 0, 0.05, 0.08, 0.13, 0.23) was investigated. Polycrystalline samples were prepared using induction melting and densified with spark plasma sintering. X-ray diffraction confirmed that the major phase of the samples possesses the trigonal CaAl2Si2-type crystal structure, and SEM/EDS indicated the presence of minor secondary phases. The electrical conductivity increases and the lattice thermal conductivity decreases with more Zn doping in YbMg1.85-xZnxBi1.98, whereas the Seebeck coefficient has a large reduction. The band gap decreases with increasing Zn concentration and leads to bipolar conduction, resulting in an increase in the thermal conductivity at higher temperatures. Figure of merit ZT values of 0.51 and 0.49 were found for the samples with x = 0 and 0.05 at 773 K, respectively. The maximum amount of Zn doping is suggested to be less than x = 0.1.
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Affiliation(s)
- Simin Wei
- School of Resources, Environment and Materials, Guangxi University, Nanning 530004, China
| | - Nailing Qin
- School of Resources, Environment and Materials, Guangxi University, Nanning 530004, China
| | - Guiying Wu
- School of Resources, Environment and Materials, Guangxi University, Nanning 530004, China
| | - Zhengbing Xu
- School of Resources, Environment and Materials, Guangxi University, Nanning 530004, China
- State Key Laboratory of Featured Metal Materials and Life-Cycle Safety for Composite Structures, Nanning 530004, China
| | - Lei Miao
- State Key Laboratory of Featured Metal Materials and Life-Cycle Safety for Composite Structures, Nanning 530004, China
- Guangxi Key Laboratory for Relativity Astrophysics, School of Physical Science and Technology, Guangxi University, Nanning 530004, China
| | - Xiyong Chen
- School of Resources, Environment and Materials, Guangxi University, Nanning 530004, China
- State Key Laboratory of Featured Metal Materials and Life-Cycle Safety for Composite Structures, Nanning 530004, China
| | - Jialin Yan
- School of Resources, Environment and Materials, Guangxi University, Nanning 530004, China
- State Key Laboratory of Featured Metal Materials and Life-Cycle Safety for Composite Structures, Nanning 530004, China
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3
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Guo M, Liu M, Zhu J, Zhu Y, Guo F, Cai W, Zhang Y, Zhang Q, Sui J. Mechanism of Thermoelectric Performance Enhancement in CaMg 2 Bi 2 -Based Materials with Different Cation Site Doping. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2306251. [PMID: 37691045 DOI: 10.1002/smll.202306251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 08/29/2023] [Indexed: 09/12/2023]
Abstract
Chemical bonds determine electron and phonon transport in solids. Tailoring chemical bonding in thermoelectric materials causes desirable or compromise thermoelectric transport properties. In this work, taking an example of CaMg2 Bi2 with covalent and ionic bonds, density functional theory calculations uncover that element Zn, respectively, replacing Ca and Mg sites cause the weakness of ionic and covalent bonding. Electrically, Zn doping at both Ca and Mg sites increases carrier concentration, while the former leads to higher carrier concentration than that of the latter because of its lower vacancy formation energy. Both doping types increase density-of-state effective mass but their mechanisms are different. The Zn doping Ca site induces resonance level in valence band and Zn doping Mg site promotes orbital alignment. Thermally, point defect and the change of phonon dispersion introduced by doping result in pronounced reduction of lattice thermal conductivity. Finally, combining with the further increase of carrier concentration caused by Na doping and the modulation of band structure and the decrease of lattice thermal conductivity caused by Ba doping, a high figure-of-merit ZT of 1.1 at 823 K in Zn doping Ca sample is realized, which is competitive in 1-2-2 Zintl phase thermoelectric systems.
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Affiliation(s)
- Muchun Guo
- School of Materials Science and Engineering, Xihua University, Chengdu, 610039, China
| | - Ming Liu
- National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin, 150001, China
| | - Jianbo Zhu
- National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin, 150001, China
| | - Yuke Zhu
- National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin, 150001, China
| | - Fengkai Guo
- National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin, 150001, China
| | - Wei Cai
- National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin, 150001, China
| | - Yongsheng Zhang
- Advanced Research Institute of Multidisciplinary Sciences, Qufu Normal University, Qufu, 273165, China
| | - QinYong Zhang
- School of Materials Science and Engineering, Xihua University, Chengdu, 610039, China
| | - Jiehe Sui
- National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin, 150001, China
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4
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Ono K, Kihou K, Usui H, Kuroki K, Goto Y, Lee CH. Rb(Zn,Cu) 4As 3 as a New High-Efficiency Thermoelectric Material. ACS OMEGA 2023; 8:42900-42906. [PMID: 38024771 PMCID: PMC10652267 DOI: 10.1021/acsomega.3c06021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Accepted: 09/29/2023] [Indexed: 12/01/2023]
Abstract
The thermoelectric performance of RbZn4-xCuxAs3 crystallized in the KCu4S3-type structure was investigated. Samples were synthesized via solid-state reactions, followed by hot pressing. Hole carriers were doped by substituting Zn with Cu until x = 0.02, resulting in an increase of the power factor from 0.049 to 0.52 mW/mK2 at T = 797 K. The lattice thermal conductivity was substantially low, with a value of 1.61 W/mK at T = 312 K, independent of doping. This can be attributed to the large vibration of the Rb atoms, as demonstrated by the neutron diffraction analysis. The maximum dimensionless figure of merit, ZT, was 0.53 at T = 797 K, representing the highest value for the 143-Zintl compounds. The result indicated that the 143-Zintl compounds could be a new class of high-performance thermoelectric materials.
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Affiliation(s)
- Keigo Ono
- National
Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan
- Department
of Applied Physics and Physico-Informatics, Faculty of Science and
Technology, Keio University, Yokohama, Kanagawa 223-8522, Japan
| | - Kunihiro Kihou
- National
Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan
| | - Hidetomo Usui
- Department
of Physics and Materials Science, Shimane
University, Matsue, Shimane 690-8504, Japan
| | - Kazuhiko Kuroki
- Department
of Physics, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Yosuke Goto
- National
Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan
| | - Chul-Ho Lee
- National
Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan
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5
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Bougoffa A, Mabrouki AE, Trabelsi A, Dhahri E, Khirouni K. Photovoltaic properties of new solar cell based on ideal cubic NaNbO 3 thin films: a combined experimental and density functional theory study. RSC Adv 2023; 13:30092-30100. [PMID: 37842673 PMCID: PMC10573870 DOI: 10.1039/d3ra04084d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2023] [Accepted: 10/07/2023] [Indexed: 10/17/2023] Open
Abstract
We explore the photovoltaic properties of a novel homojunction solar cell based on NNO(p)/NNO(n) perovskite by employing a combination of material synthesis, characterization and density functional theory calculations that are novel ideas compared to those previously reported in the literature. The band structure reveals that NaNbO3 introduces a n-type semiconductor. Moreover, using DFT calculation, we created n-NNO by a simple substitution in the O site by 4.16% fluorine atoms. Experimental and DFT calculation reveals that NNO perovskite exhibits a direct bandgap of ∼1.6 eV, with a slightly larger two other direct bandgaps of ∼2.13 and 3.24 eV. After extracting the necessary parameters, an electrical modelization of an n-NNO/p-NNO solar cell is performed by Maple software revealed that the cell conversion efficiency can reach 17% which presents a first path to identify a new solar cell based only on perovskite material.
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Affiliation(s)
- Amira Bougoffa
- Laboratory of Applied Physics, Faculty of Sciences of Sfax, University of Sfax B. P. 1171 Sfax 3000 Tunisia +21626923772
| | - Ala Eddin Mabrouki
- Laboratory of Applied Physics, Faculty of Sciences of Sfax, University of Sfax B. P. 1171 Sfax 3000 Tunisia +21626923772
| | - Abdessalem Trabelsi
- Laboratory of Applied Physics, Faculty of Sciences of Sfax, University of Sfax B. P. 1171 Sfax 3000 Tunisia +21626923772
| | - Essebti Dhahri
- Laboratory of Applied Physics, Faculty of Sciences of Sfax, University of Sfax B. P. 1171 Sfax 3000 Tunisia +21626923772
| | - Kamel Khirouni
- Laboratory of Physics of Materials and Nanomaterials Applied for Environment, Faculty of Sciences Gabes, University of Gabes 6079 Gabes Tunisia
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6
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Isotta E, Peng W, Balodhi A, Zevalkink A. Elastic Moduli: a Tool for Understanding Chemical Bonding and Thermal Transport in Thermoelectric Materials. Angew Chem Int Ed Engl 2023; 62:e202213649. [PMID: 36516061 DOI: 10.1002/anie.202213649] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 12/14/2022] [Accepted: 12/14/2022] [Indexed: 12/15/2022]
Abstract
The elastic behavior of a material can be a powerful tool to decipher thermal transport. In thermoelectrics, measuring the elastic moduli-directly tied to sound velocity-is critical to understand trends in lattice thermal conductivity, as well as study bond anharmonicity and phase transitions, given the sensitivity of elastic moduli to the chemical bonding. In this review, we introduce the basics of elasticity and explain the origin of high-temperature lattice softening from a bonding perspective. We then review elasticity data throughout classes of thermoelectrics, and explore trends in sound velocity, anharmonicity, and thermal conductivity. We reveal how experimental sound velocities can improve the accuracy of common thermal conductivity models and present a critical discussion of Grüneisen parameter estimates from elastic moduli. Readers will be equipped with tools to leverage elasticity measurements or calculations to accurately interpret thermal transport trends.
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Affiliation(s)
- Eleonora Isotta
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI, USA
| | - Wanyue Peng
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI, USA
| | - Ashiwini Balodhi
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI, USA
| | - Alexandra Zevalkink
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI, USA
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7
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Guo K, Zhang Y, Yuan S, Tang Q, Lin C, Luo P, Yang J, Pan S, Zhao LD, Cheng G, Zhang J, Luo J. NaCdSb: An Orthorhombic Zintl Phase with Exceptional Intrinsic Thermoelectric Performance. Angew Chem Int Ed Engl 2023; 62:e202212515. [PMID: 36226714 DOI: 10.1002/anie.202212515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Indexed: 11/05/2022]
Abstract
Many Zintl phases are promising thermoelectric materials owning to their features like narrow band gaps, multiband behaviors, ideal charge transport tunnels, and loosely bound cations. Herein we show a new Zintl phase NaCdSb with exceptional intrinsic thermoelectric performance. Pristine NaCdSb exhibits semiconductor behaviors with an experimental hole concentration of 2.9×1018 cm-3 and a calculated band gap of 0.5 eV. As the temperature increases, the hole concentration rises gradually and approaches its optimal one, leading to a high power factor of 11.56 μW cm-1 K-2 at 673 K. The ultralow thermal conductivity is derived from the small phonon group velocity and short phonon lifetime, ascribed to the structural anharmonicity of Cd-Sb bonds. As a consequence, a maximum zT of 1.3 at 673 K has been achieved without any doping optimization or structural modification, demonstrating that NaCdSb is a remarkable thermoelectric compound with great potential for performance improvement.
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Affiliation(s)
- Kai Guo
- School of Physics and Materials Science, Guangzhou University, Guangzhou, 510006, China.,Research Center for Advanced Information Materials (CAIM), Huangpu Research & Graduate School of Guangzhou University, Sino-Singapore Guangzhou Knowledge City Huangpu District, Guangzhou, 510555, China
| | - Yuting Zhang
- School of Materials Science and Engineering, Shanghai University, 99 Shangda Road, Shanghai, 200444, China
| | - Song Yuan
- School of Materials Science and Engineering, Shanghai University, 99 Shangda Road, Shanghai, 200444, China
| | - Qinghang Tang
- Materials Genome Institute, Shanghai University, 99 Shangda Road, Shanghai, 200444, China.,Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan, 430072, China
| | - Chen Lin
- School of Materials Science and Engineering, Shanghai University, 99 Shangda Road, Shanghai, 200444, China
| | - Pengfei Luo
- School of Materials Science and Engineering, Shanghai University, 99 Shangda Road, Shanghai, 200444, China
| | - Jiong Yang
- Materials Genome Institute, Shanghai University, 99 Shangda Road, Shanghai, 200444, China
| | - Shusheng Pan
- School of Physics and Materials Science, Guangzhou University, Guangzhou, 510006, China.,Research Center for Advanced Information Materials (CAIM), Huangpu Research & Graduate School of Guangzhou University, Sino-Singapore Guangzhou Knowledge City Huangpu District, Guangzhou, 510555, China
| | - Li-Dong Zhao
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Guofeng Cheng
- Analysis & Testing Center for Inorganic Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050, China
| | - Jiye Zhang
- School of Materials Science and Engineering, Shanghai University, 99 Shangda Road, Shanghai, 200444, China
| | - Jun Luo
- School of Materials Science and Engineering, Shanghai University, 99 Shangda Road, Shanghai, 200444, China.,Materials Genome Institute, Shanghai University, 99 Shangda Road, Shanghai, 200444, China
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8
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Structures of Three Alkaline-Earth Metal Germanides Refined from Single-Crystal X-ray Diffraction Data. CHEMISTRY 2022. [DOI: 10.3390/chemistry4040094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The calcium- and strontium- alumo-germanides SrxCa1–xAl2Ge2 (x ≈ 0.4) and SrAl2Ge2 have been synthesized and structurally characterized. Additionally, a binary calcium germanide CaGe has also been identified as a byproduct. All three crystal structures have been established from single-crystal X-ray diffraction methods and refined with high accuracy and precision. The binary CaGe crystallizes with a CrB-type structure in the orthorhombic space group Cmcm (no. 63; Z = 4; Pearson symbol oC8), where the germanium atoms are interconnected into infinite zigzag chains, formally [Ge]2−. The calcium atoms are arranged in monocapped trigonal prisms, centered by Ge atoms. SrxCa1−xAl2Ge2 (x ≈ 0.4) and SrAl2Ge2 have been confirmed to crystallize with a CaAl2Si2-type structure in the trigonal space group P3¯m1 (no. 164; Z = 1; Pearson symbol hP5), where the germanium and aluminum atoms form puckered double-layers, formally [Al2Ge2]2−. The calcium atoms are located between the layers and reside inside distorted octahedra of Ge atoms. All presented structures have a valence electron count satisfying the octet rules (e.g., Ca2+Ge2− and Ca2+[Al2Ge2]2−) and can be regarded as Zintl phases.
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9
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Hu J, Zhu J, Guo F, Qin H, Liu Y, Zhang Q, Liu Z, Cai W, Sui J. Electronic Orbital Alignment and Hierarchical Phonon Scattering Enabling High Thermoelectric Performance p-Type Mg 3Sb 2 Zintl Compounds. RESEARCH 2022; 2022:9842949. [PMID: 35582692 PMCID: PMC9079362 DOI: 10.34133/2022/9842949] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 03/24/2022] [Indexed: 11/06/2022]
Abstract
Environmentally friendly Mg3Sb2-based materials have drawn intensive attention owing to their promising thermoelectric performance. In this work, the electrical properties of p-type Mg3Sb2 are dramatically optimized by the regulation of Mg deficiency. Then, we, for the first time, found that Zn substitution at the Mg2 site leads to the alignment of px,y and pz orbital, resulting in a high band degeneracy and the dramatically enhanced Seebeck coefficient, demonstrated by the DFT calculations and electronic properties measurement. Moreover, Zn alloying decreases Mg1 (Zn) vacancies formation energy and in turn increases Mg (Zn) vacancies and optimizes the carrier concentration. Simultaneously, the Mg/Zn substitutions, Mg vacancies, and porosity structure suppress the phonon transport in a broader frequency range, leading to a low lattice thermal conductivity of ~0.47 W m-1 K-1 at 773 K. Finally, a high ZT of ~0.87 at 773 K was obtained for Mg1.95Na0.01Zn1Sb2, exceeding most of the previously reported p-type Mg3Sb2 compounds. Our results further demonstrate the promising prospects of p-type Mg3Sb2-based material in the field of mid-temperature heat recovery.
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Affiliation(s)
- Jinsuo Hu
- State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China
| | - Jianbo Zhu
- State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China
| | - Fengkai Guo
- State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China
| | - Haixu Qin
- State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China
| | - Yijie Liu
- Department of Materials Science and Engineering, Harbin Institute of Technology, Shenzhen 518055, China
| | - Qian Zhang
- Department of Materials Science and Engineering, Harbin Institute of Technology, Shenzhen 518055, China
| | - Zihang Liu
- State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China
| | - Wei Cai
- State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China
| | - Jiehe Sui
- State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China
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10
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Prediction of topological Dirac semimetal in Ca-based Zintl layered compounds CaM 2X 2 (M = Zn or Cd; X = N, P, As, Sb, or Bi). Sci Rep 2022; 12:4582. [PMID: 35301355 PMCID: PMC8930984 DOI: 10.1038/s41598-022-08370-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 03/08/2022] [Indexed: 11/10/2022] Open
Abstract
Topological Dirac materials are attracting a lot of attention because they offer exotic physical phenomena. An exhaustive search coupled with first-principles calculations was implemented to investigate 10 Zintl compounds with a chemical formula of CaM2X2 (M = Zn or Cd, X = N, P, As, Sb, or Bi) under three crystal structures: CaAl2Si2-, ThCr2Si2-, and BaCu2S2-type crystal phases. All of the materials were found to energetically prefer the CaAl2Si2-type structure based on total ground state energy calculations. Symmetry-based indicators are used to evaluate their topological properties. Interestingly, we found that CaM2Bi2 (M = Zn or Cd) are topological crystalline insulators. Further calculations under the hybrid functional approach and analysis using k · p model reveal that they exhibit topological Dirac semimetal (TDSM) states, where the four-fold degenerate Dirac points are located along the high symmetry line in-between Г to A points. These findings are verified through Green's function surface state calculations under HSE06. Finally, phonon spectra calculations revealed that CaCd2Bi2 is thermodynamically stable. The Zintl phase of AM2X2 compounds have not been identified in any topological material databases, thus can be a new playground in the search for new topological materials.
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11
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Li Y, Weng T, Li P, Huang H, He X, Guo K, Zhang J, Xing J, Li S, Jiang Y, Luo J. Improved Thermal Stability and Enhanced Thermoelectric Properties of p-Type BaCu 2Te 2 by Doping of Cl. ACS APPLIED MATERIALS & INTERFACES 2022; 14:5634-5642. [PMID: 35057614 DOI: 10.1021/acsami.1c23212] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Doping in semiconductors is a widely implemented strategy for manipulation of carrier concentration, which is a critical parameter to regulate the thermoelectric performance. Stoichiometric BaCu2Te2 shows high hole concentration and unstable transport properties owing to the inherent Cu vacancy and dynamic precipitation behavior. In this work, Te has been partially substituted by Cl in BaCu2Te2 to suppress the overhigh hole concentration. Due to the high electronegativity of Cl, strong Cl-Cu bonds can significantly inhibit the Cu migration and the consequent dynamic precipitation. Meanwhile, nano-precipitate BaCl2 distributes in the grain boundary, acting as ionic blocking layers. Therefore, the thermal stability of the samples can be essentially improved via chemical bonding strengthening and grain boundary engineering. In terms of thermal transport, the introduced point defects and second phase strengthen the short-wavelength and medium-wavelength phonon scattering, leading to further reduced thermal conductivity. Eventually, the repeatable ZT value of BaCu2Te1.98Cl0.02 reached 1.22 at 823 K, which is higher by 19.6% compared with 1.02 of pristine BaCu2Te2. The average ZTs of BaCu2Te2-xClx (x = 0, 0.02, 0.04, and 0.06) in the temperature range of 323-823 K are 0.737 for x = 0.02, 0.689 for x = 0.04, and 0.667 for x = 0.06, which are 24.6, 17.2, and 13.4% higher than the average ZT of 0.588 corresponding to the undoped sample, respectively. The study shows that synergetic enhancements of thermal stability and thermoelectric properties can be achieved by strengthening chemical bonding and constructing ionic blocking layers in the grain boundary, which can be applied to other fast-ionic conductor thermoelectric materials.
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Affiliation(s)
- Yang Li
- School of Materials Science and Engineering, Shanghai University, 99 Shangda Road, Shanghai 200444, China
| | - Tianyao Weng
- School of Materials Science and Engineering, Shanghai University, 99 Shangda Road, Shanghai 200444, China
| | - Peisi Li
- School of Materials Science and Engineering, Shanghai University, 99 Shangda Road, Shanghai 200444, China
| | - Hai Huang
- School of Materials Science and Engineering, Shanghai University, 99 Shangda Road, Shanghai 200444, China
| | - Xinliu He
- School of Materials Science and Engineering, Shanghai University, 99 Shangda Road, Shanghai 200444, China
| | - Kai Guo
- School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, China
- Research Center for Advanced Information Materials (CAIM), Huangpu Research & Graduate School of Guangzhou University, Sino-Singapore Guangzhou Knowledge City, Huangpu District, Guangzhou 510555, China
| | - Jiye Zhang
- School of Materials Science and Engineering, Shanghai University, 99 Shangda Road, Shanghai 200444, China
| | - Juanjuan Xing
- School of Materials Science and Engineering, Shanghai University, 99 Shangda Road, Shanghai 200444, China
| | - Shuankui Li
- School of Advanced Materials, Peking University Shenzhen Graduate School, Shenzhen 518055, China
| | - Ying Jiang
- Materials Genome Institute, Shanghai University, 99 Shangda Road, Shanghai 200444, China
| | - Jun Luo
- School of Materials Science and Engineering, Shanghai University, 99 Shangda Road, Shanghai 200444, China
- Materials Genome Institute, Shanghai University, 99 Shangda Road, Shanghai 200444, China
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12
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Liu D, Peng H, Sa R. Discovering the desirable physical properties of arsenic compounds AB 2As 2 and their alloys: a theoretical study. Phys Chem Chem Phys 2022; 24:26288-26296. [DOI: 10.1039/d2cp03333j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
The stability, elastic, electronic, and optical properties of AB2As2 (A = Ca, Sr; B = Mg, Zn, Cd) and their alloys with a trigonal CaAl2Si2-type structure are thoroughly examined for the first time based on the first-principles calculations.
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Affiliation(s)
- Diwen Liu
- School of Materials and Chemical Engineering, Pingxiang University, Pingxiang, 337055, China
| | - Huan Peng
- School of Materials and Chemical Engineering, Pingxiang University, Pingxiang, 337055, China
| | - Rongjian Sa
- College of Materials and Chemical Engineering, Minjiang University, Fuzhou 350108, China
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13
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Balvanz A, Baranets S, Ogunbunmi MO, Bobev S. Two Polymorphs of BaZn 2P 2: Crystal Structures, Phase Transition, and Transport Properties. Inorg Chem 2021; 60:14426-14435. [PMID: 34494828 DOI: 10.1021/acs.inorgchem.1c02209] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The novel α-BaZn2P2 structural polymorph has been synthesized and structurally characterized for the first time. Its structure, elucidated from single crystal X-ray diffraction, indicates that the compound crystallizes in the orthorhombic α-BaCu2S2 structure type, with unit cell parameters a = 9.7567(14) Å, b = 4.1266(6) Å, and c = 10.6000(15) Å. With β-BaZn2P2 being previously identified as belonging to the ThCr2Si2 family and with the precedent of structural phase transitions between the α-BaCu2S2 type and the ThCr2Si2 type, the potential for the pattern to be extended to the two different structural forms of BaZn2P2 was explored. Thermal analysis suggests that a first-order phase transition occurs at ∼1123 K, whereby the low-temperature orthorhombic α-phase transforms to a high-temperature tetragonal β-BaZn2P2, the structure of which was also studied and confirmed by single-crystal X-ray diffraction. Preliminary transport properties and band structure calculations indicate that α-BaZn2P2 is a p-type, narrow-gap semiconductor with a direct bandgap of 0.5 eV, which is an order of magnitude lower than the calculated indirect bandgap for the β-BaZn2P2 phase. The Seebeck coefficient, S(T), for the material increases steadily from the room temperature value of 119 μV/K to 184 μV/K at 600 K. The electrical resistivity (ρ) of α-BaZn2P2 is relatively high, on the order of 40 mΩ·cm, and the ρ(T) dependence shows gradual decrease upon heating. Such behavior is comparable to those of the typical semimetals or degenerate semiconductors.
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Affiliation(s)
- Adam Balvanz
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Sviatoslav Baranets
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Michael O Ogunbunmi
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Svilen Bobev
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
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Parfenov OE, Averyanov DV, Sokolov IS, Taldenkov AN, Karateev IA, Tokmachev AM, Storchak VG. High Carrier Mobility in a Layered Antiferromagnet Integrated with Silicon. ACS APPLIED MATERIALS & INTERFACES 2021; 13:41926-41932. [PMID: 34436853 DOI: 10.1021/acsami.1c13623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Coupling various functional properties in one material is always a challenge, more so if the material should be nanostructured for practical applications. Magnetism and high carrier mobility are key components for spintronic applications but rather difficult to bundle together. Here, we establish EuAl2Si2 as a layered antiferromagnet supporting high carrier mobility. Its topotactic synthesis via a sacrificial two-dimensional template results in epitaxial nanoscale films on silicon. Their outstanding structural quality and atomically sharp interfaces are demonstrated by diffraction and microscopy techniques. EuAl2Si2 films exhibit extreme magnetoresistance and a carrier mobility of above 10,000 cm2 V-1 s-1. The marriage of these properties and magnetism makes EuAl2Si2 a promising spintronic material. Importantly, the seamless integration of EuAl2Si2 with silicon technology is particularly appealing for applications.
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Affiliation(s)
- Oleg E Parfenov
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, 123182 Moscow, Russia
| | - Dmitry V Averyanov
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, 123182 Moscow, Russia
| | - Ivan S Sokolov
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, 123182 Moscow, Russia
| | - Alexander N Taldenkov
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, 123182 Moscow, Russia
| | - Igor A Karateev
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, 123182 Moscow, Russia
| | - Andrey M Tokmachev
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, 123182 Moscow, Russia
| | - Vyacheslav G Storchak
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, 123182 Moscow, Russia
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15
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Devlin KP, Chen S, Donadio D, Kauzlarich SM. Solid Solution Yb 2-xCa xCdSb 2: Structure, Thermoelectric Properties, and Quality Factor. Inorg Chem 2021; 60:13596-13606. [PMID: 34415765 DOI: 10.1021/acs.inorgchem.1c01906] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Solid solutions of Yb2-xAxCdSb2 (A = Ca, Sr, Eu; x ≤ 1) are of interest for their promising thermoelectric (TE) properties. Of these solid solutions, Yb2-xCaxCdSb2 has end members with different crystal structures. Yb2CdSb2 crystallizes in the polar space group Cmc21, whereas Ca2CdSb2 crystallizes in the centrosymmetric space group Pnma. Other solid solutions, Yb2-xAxCdSb2 (A = Sr, Eu), crystallize in the polar space group for x ≤ 1, and compositions with x ≥ 1 have not been reported. Both structure types are composed of corner-sharing CdSb4 tetrahedra condensed into sheets that differ by the stacking of the layers. Single crystals of the solid solution Yb2-xCaxCdSb2 (x = 0-1) were studied to elucidate the structural transition between the Yb2CdSb2 and Ca2CdSb2 structure types. For x ≤ 1, the structures remain in the polar space group Cmc21. As the Ca content is increased, a positional disorder arises in the intralayer cation sites (Yb2/Ca2) and the Cd site, resulting in inversion of the CdSb4 tetrahedral chain. This phenomenon could be indicative of an intergrowth of the opposing space group. The TE properties of polycrystalline samples of Yb2-xCaxCdSb2 (x ≤ 1) were measured from 300 to 525 K. The lattice thermal conductivity is extremely low (0.3-0.4 W/m·K) and the Seebeck coefficients are high (100-180 μV/K) across the temperature range. First-principles calculations show a minimum in the thermal conductivity for the x = 0.3 composition, in good agreement with experimental data. The low thermal conductivity stems from the acoustic branches being confined to low frequencies and a large number of phonon scattering channels provided by the localized optical branches. The TE quality factor of the Yb1.7A0.3CdSb2 (A = Ca, Sr, Eu) series has been calculated and predicts that the A = Ca and Sr solid solutions may not improve with carrier concentration optimization but that the Eu series is worthy of additional modifications. Overall, the x = 0.3 compositions provide the highest zT because they provide the best electronic properties with the lowest thermal conductivity.
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Affiliation(s)
- Kasey P Devlin
- Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, United States
| | - Shunda Chen
- Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, United States.,Department of Civil and Environmental Engineering, George Washington University, Washington, D.C., 20052, United States
| | - Davide Donadio
- Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, United States
| | - Susan M Kauzlarich
- Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, United States
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16
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Gibson QD, Zhao T, Daniels LM, Walker HC, Daou R, Hébert S, Zanella M, Dyer MS, Claridge JB, Slater B, Gaultois MW, Corà F, Alaria J, Rosseinsky MJ. Low thermal conductivity in a modular inorganic material with bonding anisotropy and mismatch. Science 2021; 373:1017-1022. [PMID: 34446603 DOI: 10.1126/science.abh1619] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 06/25/2021] [Indexed: 12/17/2022]
Abstract
The thermal conductivity of crystalline materials cannot be arbitrarily low, as the intrinsic limit depends on the phonon dispersion. We used complementary strategies to suppress the contribution of the longitudinal and transverse phonons to heat transport in layered materials that contain different types of intrinsic chemical interfaces. BiOCl and Bi2O2Se encapsulate these design principles for longitudinal and transverse modes, respectively, and the bulk superlattice material Bi4O4SeCl2 combines these effects by ordering both interface types within its unit cell to reach an extremely low thermal conductivity of 0.1 watts per kelvin per meter at room temperature along its stacking direction. This value comes within a factor of four of the thermal conductivity of air. We demonstrated that chemical control of the spatial arrangement of distinct interfaces can synergically modify vibrational modes to minimize thermal conductivity.
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Affiliation(s)
- Quinn D Gibson
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, UK
| | - Tianqi Zhao
- Department of Chemistry, University College London, 20 Gordon Street, Kings Cross, London WC1H 0AJ, UK
| | - Luke M Daniels
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, UK
| | - Helen C Walker
- ISIS Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, UK
| | - Ramzy Daou
- Laboratoire CRISMAT, UMR 6508 CNRS, ENSICAEN, UNICAEN, Normandie Université, 6 bd du Maréchal Juin, 14050 Caen, France
| | - Sylvie Hébert
- Laboratoire CRISMAT, UMR 6508 CNRS, ENSICAEN, UNICAEN, Normandie Université, 6 bd du Maréchal Juin, 14050 Caen, France
| | - Marco Zanella
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, UK
| | - Matthew S Dyer
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, UK
| | - John B Claridge
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, UK
| | - Ben Slater
- Department of Chemistry, University College London, 20 Gordon Street, Kings Cross, London WC1H 0AJ, UK
| | - Michael W Gaultois
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, UK.,Leverhulme Research Centre for Functional Materials Design, The Materials Innovation Factory, University of Liverpool 51 Oxford Street, Liverpool L7 3NY, UK
| | - Furio Corà
- Department of Chemistry, University College London, 20 Gordon Street, Kings Cross, London WC1H 0AJ, UK
| | - Jonathan Alaria
- Department of Physics, University of Liverpool, Oliver Lodge Laboratory, Liverpool L69 ZE, UK.
| | - Matthew J Rosseinsky
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, UK.
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17
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Zheng Y, Slade TJ, Hu L, Tan XY, Luo Y, Luo ZZ, Xu J, Yan Q, Kanatzidis MG. Defect engineering in thermoelectric materials: what have we learned? Chem Soc Rev 2021; 50:9022-9054. [PMID: 34137396 DOI: 10.1039/d1cs00347j] [Citation(s) in RCA: 66] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Thermoelectric energy conversion is an all solid-state technology that relies on exceptional semiconductor materials that are generally optimized through sophisticated strategies involving the engineering of defects in their structure. In this review, we summarize the recent advances of defect engineering to improve the thermoelectric (TE) performance and mechanical properties of inorganic materials. First, we introduce the various types of defects categorized by dimensionality, i.e. point defects (vacancies, interstitials, and antisites), dislocations, planar defects (twin boundaries, stacking faults and grain boundaries), and volume defects (precipitation and voids). Next, we discuss the advanced methods for characterizing defects in TE materials. Subsequently, we elaborate on the influences of defect engineering on the electrical and thermal transport properties as well as mechanical performance of TE materials. In the end, we discuss the outlook for the future development of defect engineering to further advance the TE field.
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Affiliation(s)
- Yun Zheng
- Key Laboratory of Optoelectronic Chemical Materials and Devices, Ministry of Education, Jianghan University, Wuhan 430056, China
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18
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Pöhls JH, Chanakian S, Park J, Ganose AM, Dunn A, Friesen N, Bhattacharya A, Hogan B, Bux S, Jain A, Mar A, Zevalkink A. Experimental validation of high thermoelectric performance in RECuZnP 2 predicted by high-throughput DFT calculations. MATERIALS HORIZONS 2021; 8:209-215. [PMID: 34821299 DOI: 10.1039/d0mh01112f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Accurate density functional theory calculations of the interrelated properties of thermoelectric materials entail high computational cost, especially as crystal structures increase in complexity and size. New methods involving ab initio scattering and transport (AMSET) and compressive sensing lattice dynamics are used to compute the transport properties of quaternary CaAl2Si2-type rare-earth phosphides RECuZnP2 (RE = Pr, Nd, Er), which were identified to be promising thermoelectrics from high-throughput screening of 20 000 disordered compounds. Experimental measurements of the transport properties agree well with the computed values. Compounds with stiff bulk moduli (>80 GPa) and high speeds of sound (>3500 m s-1) such as RECuZnP2 are typically dismissed as thermoelectric materials because they are expected to exhibit high lattice thermal conductivity. However, RECuZnP2 exhibits not only low electrical resistivity, but also low lattice thermal conductivity (∼1 W m-1 K-1). Contrary to prior assumptions, polar-optical phonon scattering was revealed by AMSET to be the primary mechanism limiting the electronic mobility of these compounds, raising questions about existing assumptions of scattering mechanisms in this class of thermoelectric materials. The resulting thermoelectric performance (zT of 0.5 for ErCuZnP2 at 800 K) is among the best observed in phosphides and can likely be improved with further optimization.
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Affiliation(s)
- Jan-Hendrik Pöhls
- Department of Chemistry, University of Alberta, Edmonton, AB T6G 2G2, Canada.
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Guo M, Guo F, Zhu J, Yin L, Zhang Q, Cai W, Sui J. Achieving High Thermoelectric Performance in Rare-Earth Element-Free CaMg 2Bi 2 with High Carrier Mobility and Ultralow Lattice Thermal Conductivity. RESEARCH 2020; 2020:5016564. [PMID: 32783029 PMCID: PMC7396126 DOI: 10.34133/2020/5016564] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 07/09/2020] [Indexed: 11/27/2022]
Abstract
CaMg2Bi2-based compounds, a kind of the representative compounds of Zintl phases, have uniquely inherent layered structure and hence are considered to be potential thermoelectric materials. Generally, alloying is a traditional and effective way to reduce the lattice thermal conductivity through the mass and strain field fluctuation between host and guest atoms. The cation sites have very few contributions to the band structure around the fermi level; thus, cation substitution may have negligible influence on the electric transport properties. What is more, widespread application of thermoelectric materials not only desires high ZT value but also calls for low-cost and environmentally benign constituent elements. Here, Ba substitution on cation site achieves a sharp reduction in lattice thermal conductivity through enhanced point defects scattering without the obvious sacrifice of high carrier mobility, and thus improves thermoelectric properties. Then, by combining further enhanced phonon scattering caused by isoelectronic substitution of Zn on the Mg site, an extraordinarily low lattice thermal conductivity of 0.51 W m−1 K−1 at 873 K is achieved in (Ca0.75Ba0.25)0.995Na0.005Mg1.95Zn0.05Bi1.98 alloy, approaching the amorphous limit. Such maintenance of high mobility and realization of ultralow lattice thermal conductivity synergistically result in broadly improvement of the quality factor β. Finally, a maximum ZT of 1.25 at 873 K and the corresponding ZTave up to 0.85 from 300 K to 873 K have been obtained for the same composition, meanwhile possessing temperature independent compatibility factor. To our knowledge, the current ZTave exceeds all the reported values in AMg2Bi2-based compounds so far. Furthermore, the low-cost and environment-friendly characteristic plus excellent thermoelectric performance also make the present Zintl phase CaMg2Bi2 more competitive in practical application.
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Affiliation(s)
- Muchun Guo
- National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001, China
| | - Fengkai Guo
- National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001, China
| | - Jianbo Zhu
- National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001, China
| | - Li Yin
- Department of Materials Science and Engineering, Harbin Institute of Technology, Shenzhen, Guangdong 518055, China
| | - Qian Zhang
- Department of Materials Science and Engineering, Harbin Institute of Technology, Shenzhen, Guangdong 518055, China
| | - Wei Cai
- National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001, China
| | - Jiehe Sui
- National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001, China
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Guo M, Guo F, Zhu J, Yin L, Qin H, Zhang Q, Cai W, Sui J. Enhanced Thermoelectric Properties of p-Type CaMg 2Bi 2 via a Synergistic Effect Originated from Zn and Alkali-Metal Co-doping. ACS APPLIED MATERIALS & INTERFACES 2020; 12:6015-6021. [PMID: 31913592 DOI: 10.1021/acsami.9b22333] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Bi-based Zintl phase CaMg2Bi2 is a promising thermoelectric material. Here, we report that the high-concentration point defects induced by equivalent Zn doping on the Mg site significantly enhance phonon scattering and then suppress lattice thermal conductivity by 50% at room temperature. Subsequently, partial substitution of divalent calcium ions with alkali-ion doping (Li, Na, K) not only optimizes the electrical transport properties by increasing the carrier concentration but also further reduces the lattice thermal conductivity through crystal disorder. Finally, the synergistic effect of Zn and Li co-doping leads to a high ZT of ∼1.0 at 873 K and an average ZT of 0.6 between 300 and 873 K for Ca0.995Li0.005Mg1.9Zn0.1Bi1.98. This work demonstrates an instructive method to reduce the lattice thermal conductivity via doping at the Mg site, which has never been reported in the CaMg2Bi2 system. Moreover, high-performance Ca0.995Li0.005Mg1.9Zn0.1Bi1.98 alloy does not contain any toxic elements and expensive rare earth elements, which is of great significance for the development of environment-friendly thermoelectric materials.
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Affiliation(s)
- Muchun Guo
- National Key Laboratory for Precision Hot Processing of Metals , Harbin Institute of Technology , Harbin 150001 , China
| | - Fengkai Guo
- National Key Laboratory for Precision Hot Processing of Metals , Harbin Institute of Technology , Harbin 150001 , China
| | - Jianbo Zhu
- National Key Laboratory for Precision Hot Processing of Metals , Harbin Institute of Technology , Harbin 150001 , China
| | - Li Yin
- Department of Materials Science and Engineering , Harbin Institute of Technology , Shenzhen , Guangdong 518055 , China
| | - Haixu Qin
- National Key Laboratory for Precision Hot Processing of Metals , Harbin Institute of Technology , Harbin 150001 , China
| | - Qian Zhang
- Department of Materials Science and Engineering , Harbin Institute of Technology , Shenzhen , Guangdong 518055 , China
| | - Wei Cai
- National Key Laboratory for Precision Hot Processing of Metals , Harbin Institute of Technology , Harbin 150001 , China
| | - Jiehe Sui
- National Key Laboratory for Precision Hot Processing of Metals , Harbin Institute of Technology , Harbin 150001 , China
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22
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Limits of Cation Solubility in AMg₂Sb₂ ( A = Mg, Ca, Sr, Ba) Alloys. MATERIALS 2019; 12:ma12040586. [PMID: 30781389 PMCID: PMC6416610 DOI: 10.3390/ma12040586] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 02/11/2019] [Accepted: 02/13/2019] [Indexed: 11/18/2022]
Abstract
AM2X2 compounds that crystallize in the CaAl2Si2 structure type have emerged as a promising class of n- and p-type thermoelectric materials. Alloying on the cation (A) site is a frequently used approach to optimize the thermoelectric transport properties of AM2X2 compounds, and complete solid solubility has been reported for many combinations of cations. In the present study, we investigate the phase stability of the AMg2Sb2 system with mixed occupancy of Mg, Ca, Sr, or Ba on the cation (A) site. We show that the small ionic radius of Mg2+ leads to limited solubility when alloyed with larger cations such as Sr or Ba. Phase separation observed in such cases indicates a eutectic-like phase diagram. By combining these results with prior alloying studies, we establish an upper limit for cation radius mismatch in AM2X2 alloys to provide general guidance for future alloying and doping studies.
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Quaternary rare-earth transition-metal phosphides REMnCuP2 (RE = Y, La–Nd, Sm, Gd–Tm, Lu) with CaAl2Si2-type structure and a polymorph of LaMnCuP2 with BaCu2S2-type structure. J SOLID STATE CHEM 2019. [DOI: 10.1016/j.jssc.2018.09.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Exploratory Work in the Quaternary System of Ca⁻Eu⁻Cd⁻Sb: Synthesis, Crystal, and Electronic Structures of New Zintl Solid Solutions. MATERIALS 2018; 11:ma11112146. [PMID: 30384471 PMCID: PMC6265713 DOI: 10.3390/ma11112146] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 10/24/2018] [Accepted: 10/29/2018] [Indexed: 11/17/2022]
Abstract
Investigation of the quaternary system, Ca–Eu–Cd–Sb, led to a discovery of the new solid solutions, Ca1−xEuxCd2Sb2, with the CaAl2Si2 structure type (x ≈ 0.3–0.9, hP5, P3¯m1, a = 4.6632(5)–4.6934(3) Å, c = 7.630(1)–7.7062(7) Å), Ca2−xEuxCdSb2 with the Yb2CdSb2 type (x ≈ 0.6, oS20, Cmc21, a = 4.646(2) Å, b = 17.733(7) Å, c = 7.283(3) Å), and Eu11−xCaxCd6Sb12 with the Sr11Cd6Sb12 type (x ≈ 1, mS58, C2/m, a = 32.407(4) Å, b = 4.7248(5) Å, c = 12.377(1) Å, β = 109.96(1)°). Systematic crystallographic studies of the Ca1−xEuxCd2Sb2 series indicated expansion of the unit cell upon an increase in the Eu content, in accordance with a larger ionic radius of Eu2+ vs. Ca2+. The Ca2−xEuxCdSb2 composition with x ≈ 0.6 adopts the non-centrosymmetric space group, Cmc21, although the parent ternary phase, Ca2CdSb2, crystallizes in the centrosymmetric space group, Pnma. Two non-equivalent Ca sites in the layered crystal structure of Ca2−xEuxCdSb2 get unevenly occupied by Eu, with a preference for the interlayer position, which offers a larger available volume. Similar size-driven preferred occupation is observed in the Eu11−xCaxCd6Sb12 solid solution with x ≈ 1.
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