First‐Principles Calculations of Pressure Effects on the Structural, Electronic, Elastic, and Thermodynamic Properties of Rb₂MF₆ (M = Si, Ni, Pd) Crystals

Abstract

Among the various groups of isostructural compounds (e.g., spinels, garnets, chalcopyrites, elpasolites, etc.) with important functional applications, the perovskite (named after a Russian mineralogist L.A. Perovski) family of materials occupy a special place. Perovskites are known for a long time and are investigated rigorously due to their many potential practical applications. A wide range of cationic and anionic substitutions are possible due to the flexibility of the perovskite structure.The perovskites' general chemical formula is ABX 3 , where X is a halide anion or oxygen, and A, B are two cations. The structural, luminescent, and photovoltaic properties of various representatives of perovskite materials, neat, and with various impurities, have been studied in detail. [1][2][3][4][5][6] The double perovskites have a "doubled" chemical formula that can be written as A 2 BB'X 6 or A 2 CX 6 , where A, B, B', C are various cations in a suitable oxidation state dictated by the nature and number of anions (oxygen or halide ions). Some examples of these compounds can be as follows: