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

• Two new thermodynamically metastable ZrO2–SiO2 compounds are predicted.
• The predicated P-43mP-43m or P4¯3m-Zr3SiO8 has the highest dielectric constant and refractive index.
• I41/aI41/a-ZrSiO4 shows the highest electric energy density among ZrO2–SiO2 dielectrics.

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 ZrO2–SiO2 dielectrics. The calculation reproduced two already known structures (I41/amdI41/amd-ZrSiO4 and I41/aI41/a-ZrSiO4) and predicted two new thermodynamically metastable structures Zr3SiO8 (P4¯3m) and ZrSi2O6 (P3¯1m). At ambient pressure, the only thermodynamically stable zirconium silicate is I41/amdI41/amd-ZrSiO4 (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 ZrSiO4. 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 P4¯3m-Zr3SiO8 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 ZrO2–SiO2, maximum occurs for I41/aI41/a-ZrSiO4.