High-Pressure Modification of BiI3

Abstract

Structural and optical properties as well as chemical bonding of BiI 3 at elevated pressures are investigated by means of refinements of X-ray powder diffraction data, measurements of the optical absorption, and calculations of the band structure involving bonding analysis in real space. The data evidence the onset of a phase transition from trigonal (hR24) BiI3 into PuBr 3 -type (oS16) BiI 3 around 4.6 GPa. This high-pressure modification remains stable up to 40 GPa, the highest pressure of this study. The phase exhibits semiconducting properties with constantly decreasing band gap between 5 and 18 GPa. Above this pressure, the absorbance edge broadens significantly. Extrapolation of the determined band gap values implies a semiconductor to metal transition at approximately 35 GPa. The value is in accordance with subtle structural anomalies and the results of band structure calculations. Topological analysis of the computed electron density and the electron-localizability indicator reveal fingerprints for weak covalent Bi-I contributions in addition to dominating ionic interactions for both modifications.Inorganics 2019, 7, 143 2 of 12 and showed clear indications of non-hydrostatic pressure conditions. Thus, we reinvestigated the nature of the high-pressure polymorph of BiI 3 by performing high-resolution high-pressure investigations under hydrostatic pressure conditions using helium as the pressure transmitting medium. The pressure-induced changes of the electronic band gap are characterized by the measurements of the optical absorbance in the visible range. In addition, the changes of the electronic structure as well as those of the chemical bonding are studied by means of DFT full-potential electronic band structure calculations.

Pressure-driven structural and electronic transitions in a quasimolecular layered compound of antimony triiodide

“…9 Recently, BiI 3 has been reported to undergo a semiconductor-to-metal transformation at ∼35.0 GPa by means of optical absorption measurements under quasi-hydrostatic condition using CsI powder as the PM. 42 In the present work, both Raman scattering and electrical conductivity results disclosed the occurrence of an electronic transition in SbI 3 at 32.3 GPa under non-hydrostatic condition. Nevertheless, SbI 3 metallizes at higher pressure of 37.6 GPa under hydrostatic condition using helium as the PM.…”

Influence of crystal structure and composition on optical and electronic properties of pyridinium-based bismuth iodide complexes

“…However, concerns over the toxicity of lead halide complexes and the instability of lead(II) halide complexes, have propelled research into environmentally friendly alternatives. [5][6][7][8][9][10][11] Several perovskite-like compositions such as A 3 M 2 I 9 , A 3 MX 6 , and AMX 4 (X = Cl, Br, I) have been proposed, where Pb 2+ is partially or fully replaced by metal cations such as Bi 3+ /In 3+ /Sb 3+ /Fe 3+ /Mn 2+ /Sn 2+ /Co 2+ /Ge 2+ and monovalent cations (A: organic methylammonium (MA + ) or inorganic cation e.g. K + , Rb + , NH 4 + , K + , Cs + , Ag + , Tl + ).…”

Topological analysis of chemical bonding in the layered FePSe3 upon pressure‐induced phase transitions

“…[3][4][5][6][7][8][9][10][11][12][13][14][15] In particular, the method helps to identify changes in chemical bonds and mechanisms of phase transitions under high pressure. [16][17][18][19][20][21][22][23][24][25][26] At the same time, the use of topological analysis for the understanding of bonding in layered compounds is not numerous. Recently it was successfully employed to evidence peculiarities of chemical bonding in layered TiS 2 crystals using the analysis of the electron density, obtained from synchrotron X-ray diffraction data and density functional theory calculations.…”