Statistical Analysis of Coordination Environments in Oxides

Coordination or local environments (e.g., tetrahedra and octahedra) are powerful descriptors of the crystalline structure of materials. These structural descriptors are essential to the understanding of crystal chemistry and the design of new materials. However, extensive statistics on the occurrence of local environment are not available even on common chemistries such as oxides. Here, we present the first large-scale statistical analysis of the coordination environments of cations in oxides using a large set of experimentally observed compounds (about 8000). Using a newly developed method, we provide the distribution of local environment for each cation in oxides. We discuss our results highlighting previously known trends and unexpected coordination environments, as well as compounds presenting very rare coordinations. Our work complements the know-how of the solid state chemist with a statistically sound analysis and paves the way for further data mining efforts linking, for instance, coordination environments to materials properties

High-Mobility Bismuth-based Transparent <i>p</i>‑Type Oxide from High-Throughput Material Screening

High-Mobility Bismuth-based Transparent <i>p</i>‑Type Oxide from High-Throughput Material Screenin

Parsed phonon data

Json files containing the phonon related quantities extracted from the DFPT calculation

DDB files

A collection of Abinit DDB files. Contain the raw data extracted from the DFPT calculations

When Density Functional Approximations Meet Iron Oxides

Three density functional approximations (DFAs), PBE, PBE+<i>U</i>, and Heyd–Scuseria–Ernzerhof screened hybrid functional (HSE), were employed to investigate the geometric, electronic, magnetic, and thermodynamic properties of four iron oxides, namely, α-FeOOH, α-Fe₂O₃, Fe₃O₄, and FeO. Comparing our calculated results with available experimental data, we found that HSE (<i>a</i> = 0.15) (containing 15% “screened” Hartree–Fock exchange) can provide reliable values of lattice constants, Fe magnetic moments, band gaps, and formation energies of all four iron oxides, while standard HSE (<i>a</i> = 0.25) seriously overestimates the band gaps and formation energies. For PBE+<i>U</i>, a suitable <i>U</i> value can give quite good results for the electronic properties of each iron oxide, but it is challenging to accurately get other properties of the four iron oxides using the same <i>U</i> value. Subsequently, we calculated the Gibbs free energies of transformation reactions among iron oxides using the HSE (<i>a</i> = 0.15) functional and plotted the equilibrium phase diagrams of the iron oxide system under various conditions, which provide reliable theoretical insight into the phase transformations of iron oxides