High throughput exploration of ZrxSi1−xO2 dielectrics by evolutionary first-principles approaches

Abstract

Abstract The high throughput approaches aim to discover, screen and optimize materials in a cost-effective way and to shorten their time-to-market. However, computational approaches typically involve a combinatorial explosion problem, to deal with which, we adopted hybrid evolutionary algorithms together with first-principle calculations to explore possible stable and metastable crystal structures of ZrO 2 –SiO 2 dielectrics. The calculation reproduced two already known structures ( I 4 1 / a m d -ZrSiO 4 and I 4 1 / a -ZrSiO 4 ) and predicted two new thermodynamically metastable structures Zr 3 SiO 8 ( P 4 ¯ 3 m ) and ZrSi 2 O 6 ( P 3 ¯ 1 m ). At ambient pressure, the only thermodynamically stable zirconium silicate is I 4 1 / a m d -ZrSiO 4 (zircon). Dynamical stability of the new phases has been verified by phonon calculations, and their static dielectric constants are higher than that of the known phases of ZrSiO 4 . Band structure, density of state, electron localization function and Bader charges are presented and discussed. The new metastable structures are insulators with the DFT band gaps of 3.65 and 3.52 eV, respectively. Calculations show that P 4 ¯ 3 m -Zr 3 SiO 8 has high dielectric constant (∼20.7), high refractive index (∼2.4) and strong dispersion of light. Global optimization of the dielectric fitness (electric energy density) shows that among crystalline phases of ZrO 2 –SiO 2 , maximum occurs for I 4 1 / a -ZrSiO 4 .