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Modulation of the electronic structure and thermoelectric properties of orthorhombic and cubic SnSe by AgBiSe2 alloying
Chemical Science ( IF 8.4 ) Pub Date : 2021-08-31 , DOI: 10.1039/d1sc03696c Sushmita Chandra 1, 2 , Raagya Arora 3, 4 , Umesh V Waghmare 2, 4 , Kanishka Biswas 1, 2
Chemical Science ( IF 8.4 ) Pub Date : 2021-08-31 , DOI: 10.1039/d1sc03696c Sushmita Chandra 1, 2 , Raagya Arora 3, 4 , Umesh V Waghmare 2, 4 , Kanishka Biswas 1, 2
Affiliation
Recently, single-crystals of tin selenide (SnSe) have drawn immense attention in the field of thermoelectrics due to their anisotropic layered crystal structure and ultra-low lattice thermal conductivity. Layered SnSe has an orthorhombic crystal structure (Pnma) at ambient conditions. However, the cubic rock-salt phase (Fmm) of SnSe can only be stabilized at very high pressure and thus, the experimental realization of the cubic phase remains elusive. Herein, we have successfully stabilized the high-pressure cubic rock-salt phase of SnSe by alloying with AgBiSe2 (0.30 ≤ x ≤ 0.80) at ambient temperature and pressure. The orthorhombic polycrystalline phase is stable in (SnSe)1−x(AgBiSe2)x in the composition range of 0.00 ≤ x < 0.28, which corresponds to narrow band gap semiconductors, whereas the band gap closes upon increasing the concentration of AgBiSe2 (0.30 ≤ x < 0.70) leading to the cubic rock-salt structure. We confirmed the stabilization of the cubic structure at x = 0.30 and associated changes in the electronic structure using first-principles theoretical calculations. The pristine cubic SnSe exhibited the topological crystalline insulator (TCI) quantum phase, but the cubic (SnSe)1−x(AgBiSe2)x (x = 0.33) showed a semi-metallic electronic structure with overlapping conduction and valence bands. The cubic polycrystalline (SnSe)1−x(AgBiSe2)x (x = 0.30) sample showed n-type conduction at room temperature, while the orthorhombic (SnSe)1−x(AgBiSe2)x (0.00 ≤ x < 0.28) samples retained p-type character. Thus, by optimizing the electronic structure and the thermoelectric properties of polycrystalline SnSe, a high zT of 1.3 at 823 K has been achieved in (SnSe)0.78(AgBiSe2)0.22.
中文翻译:
AgBiSe2合金化对正交和立方SnSe的电子结构和热电性能的调制
近年来,硒化锡(SnSe)单晶由于其各向异性的层状晶体结构和超低的晶格热导率而在热电领域引起了极大的关注。层状 SnSe在环境条件下具有正交晶体结构 ( Pnma )。然而,SnSe的立方岩盐相 ( Fm m ) 只能在非常高的压力下稳定,因此立方相的实验实现仍然难以实现。在此,我们通过在环境温度和压力下与 AgBiSe 2 (0.30 ≤ x ≤ 0.80)合金化成功地稳定了 SnSe 的高压立方岩盐相。正交多晶相在 (SnSe) 1− x (AgBiSe ) 中稳定2 ) x在 0.00 ≤ x < 0.28的组成范围内,这对应于窄带隙半导体,而带隙在增加 AgBiSe 2 (0.30 ≤ x < 0.70)的浓度时关闭,导致立方岩盐结构。我们使用第一性原理理论计算证实了x = 0.30 时立方结构的稳定性以及电子结构的相关变化。原始立方 SnSe 表现出拓扑晶体绝缘体 (TCI) 量子相,但立方 (SnSe) 1− x (AgBiSe 2 ) x ( x ( x= 0.33) 显示出具有重叠导带和价带的半金属电子结构。立方多晶 (SnSe) 1− x (AgBiSe 2 ) x ( x = 0.30) 样品在室温下显示 n 型导电,而正交多晶 (SnSe) 1− x (AgBiSe 2 ) x (0.00 ≤ x < 0.28)样品保留了 p 型特征。因此,通过优化多晶 SnSe 的电子结构和热电特性,在 (SnSe) 0.78 (AgBiSe 2 ) 0.22 中实现了 823 K 时 1.3的高zT。
更新日期:2021-09-15
中文翻译:
AgBiSe2合金化对正交和立方SnSe的电子结构和热电性能的调制
近年来,硒化锡(SnSe)单晶由于其各向异性的层状晶体结构和超低的晶格热导率而在热电领域引起了极大的关注。层状 SnSe在环境条件下具有正交晶体结构 ( Pnma )。然而,SnSe的立方岩盐相 ( Fm m ) 只能在非常高的压力下稳定,因此立方相的实验实现仍然难以实现。在此,我们通过在环境温度和压力下与 AgBiSe 2 (0.30 ≤ x ≤ 0.80)合金化成功地稳定了 SnSe 的高压立方岩盐相。正交多晶相在 (SnSe) 1− x (AgBiSe ) 中稳定2 ) x在 0.00 ≤ x < 0.28的组成范围内,这对应于窄带隙半导体,而带隙在增加 AgBiSe 2 (0.30 ≤ x < 0.70)的浓度时关闭,导致立方岩盐结构。我们使用第一性原理理论计算证实了x = 0.30 时立方结构的稳定性以及电子结构的相关变化。原始立方 SnSe 表现出拓扑晶体绝缘体 (TCI) 量子相,但立方 (SnSe) 1− x (AgBiSe 2 ) x ( x ( x= 0.33) 显示出具有重叠导带和价带的半金属电子结构。立方多晶 (SnSe) 1− x (AgBiSe 2 ) x ( x = 0.30) 样品在室温下显示 n 型导电,而正交多晶 (SnSe) 1− x (AgBiSe 2 ) x (0.00 ≤ x < 0.28)样品保留了 p 型特征。因此,通过优化多晶 SnSe 的电子结构和热电特性,在 (SnSe) 0.78 (AgBiSe 2 ) 0.22 中实现了 823 K 时 1.3的高zT。