Large resistivity reduction in mixed-valent CsAuBr3 under pressure

Abstract

We report on high-pressure p ≤ 45 GPa resistivity measurements on the perovskite-related mixedvalent compound CsAuBr 3 . The compounds high-pressure resistivity can be classified into three regions: For low pressures (p < 10 GPa) an insulator to metal transition is observed; between p = 10 GPa and 14 GPa the room temperature resistivity goes through a minimum and increases again; above p = 14 GPa a semiconducting state is observed. From this pressure up to the highest pressure of p = 45 GPa reached in this experiment, the room-temperature resistivity remains nearly constant. We find an extremely large resistivity reduction between ambient pressure and 10 GPa by more than 6 orders of magnitude. This decrease is among the largest reported changes in the resistivity for this narrow pressure regime. We show -by an analysis of the electronic band structure evolution of this material -that the large change in resistivity under pressure in not caused by a crossing of the bands at the Fermi level. We find that it instead stems from two bands that are pinned at the Fermi level and that are moving towards one another as a consequence of the mixed-valent to single-valent transition. This mechanism appears to be especially effective for the rapid buildup of the density of states at the Fermi level. arXiv:1909.06874v1 [cond-mat.mtrl-sci]

Charge Reservoirs in an Expanded Halide Perovskite Analog: Enhancing High‐Pressure Conductivity through Redox‐Active Molecules

“…Halide perovskites are highly compressible, with a large electronic response to pressure. [25] Increases in conductivity upon compression occur in a range of halide perovskites including single ((CH 3 NH 3 )PbI 3 ), [11] double (Cs 2 Au I Au III X 3 ; X = Cl À , Br À , I À ), [26,27] and 2D perovskites (R 2 CuX 4 ; R = organic cation, X = Cl À , Br À ). [28,29] We, therefore, studied the pressure response of 1I, hypothesizing that the redox activity of dmpz would contribute to its high-pressure properties.…”

Charge Reservoirs in an Expanded Halide Perovskite Analog: Enhancing High‐Pressure Conductivity through Redox‐Active Molecules

“…Halide perovskites are highly compressible, with a large electronic response to pressure. [25] Increases in conductivity upon compression occur in a range of halide perovskites including single ((CH 3 NH 3 )PbI 3 ), [11] double (Cs 2 Au I Au III X 3 ; X = Cl À , Br À , I À ), [26,27] and 2D perovskites (R 2 CuX 4 ; R = organic cation, X = Cl À , Br À ). [28,29] We, therefore, studied the pressure response of 1I, that the redox activity of dmpz would contribute to its high-pressure properties.…”

Advances in flexible piezoresistive pressure sensor

“…No current passing through adjacent NWs 图 1 (a)半导体硅在 [111]和[100]波数方向的导带和价带 [34] ; (b)化合物CsAuBr 3 在27 ℃下, 45 GPa压力范围内电阻率的变 化 [35] ; (c)石墨烯片层沿指定方向均匀拉伸或压缩 [38] ; (d)通过按压导电聚合物复合材料降低电阻率的示意图 [45] ; (e) 相邻纳米线 之间的不同电接触情况 [50] Fig. 1.…”

“…1. (a) Conduction band and valence band in silicon along [111] and [100] k-directions [34] ; (b) Evolution of the resistivity of CsAuBr 3 at 27 ℃ in a pressure range up to 45 GPa [35] ; (c) the graphene sheet is uniformly stretched or compressed along a prescribed direction [38] ; (d) schematic illustration of decrease in resistivity by pressing a conductive polymer composite [45] ; (e) different electrical interconnections between two adjacent NWs [45] . 导电层产生裂纹甚至从变形层脱落的现象 [39] .…”