TY - JOUR

T1 - DFT calculations of the stability field and properties of a predicted lanthanum–scandium–aluminum garnet La3Sc2Al3O12 and P–T phase diagram of Y3Sc2Al3O12

AU - Sagatova, Dinara N.

AU - Sagatov, Nursultan E.

AU - Gavryushkin, Pavel N.

AU - Solodovnikov, Sergey F.

N1 - This study was funded by the Russian Science Foundation , project no. 23-13-00117 ( https://rscf.ru/project/23-13-00117/ ). The computations were performed using resources provided by the Novosibirsk State University Supercomputer Center.

PY - 2024/7

Y1 - 2024/7

N2 - In this study we present the results of our density functional theory calculations within the quasi-harmonic approximation, which predict formation and properties of a new compound of the garnet family, La3Sc2Al3O12 (LSAG). LSAG was shown to be formed from 3LaAlO3 + Sc2O3 at ambient pressure and room temperature. The thermodynamic stability region of LSAG is limited by a temperature of 685 K, above which its decomposition into LaAlO3 (LAP) and Sc2O3 occurs. With increasing pressure, LSAG retains its stability up to 0.23 GPa, where the decomposition reaction LSAG↔3LAP＋ Sc2O3 becomes thermodynamically favorable. In this work, not only the thermodynamic stability of LSAG was assessed, but also its thermal conductivity, elastic constants and band gap were calculated. At 300 K the thermal conductivity of LSAG is 13.204 Wm−1K−1. LSAG has the smallest elastic constants compared with YSAG and YAG, which indicates weaker atomic bonding in LSAG than in YSAG and YAG. The width of band gap of LSAG calculated using an hybrid functional is equal to 5.24 eV. In addition, the P–T phase diagram of the known Y3Sc2Al3O12 (YSAG) was calculated for the first time. Unlike LSAG, YSAG is stable at fairly high temperatures, reaching values of at least 1500 K. With increasing temperature to 1500 K, the pressure of the phase transition increases slightly to 3.55 GPa, and the monovariant curve of the reaction YSAG↔3YAP+Sc2O3 is represented by an almost straight line.

AB - In this study we present the results of our density functional theory calculations within the quasi-harmonic approximation, which predict formation and properties of a new compound of the garnet family, La3Sc2Al3O12 (LSAG). LSAG was shown to be formed from 3LaAlO3 + Sc2O3 at ambient pressure and room temperature. The thermodynamic stability region of LSAG is limited by a temperature of 685 K, above which its decomposition into LaAlO3 (LAP) and Sc2O3 occurs. With increasing pressure, LSAG retains its stability up to 0.23 GPa, where the decomposition reaction LSAG↔3LAP＋ Sc2O3 becomes thermodynamically favorable. In this work, not only the thermodynamic stability of LSAG was assessed, but also its thermal conductivity, elastic constants and band gap were calculated. At 300 K the thermal conductivity of LSAG is 13.204 Wm−1K−1. LSAG has the smallest elastic constants compared with YSAG and YAG, which indicates weaker atomic bonding in LSAG than in YSAG and YAG. The width of band gap of LSAG calculated using an hybrid functional is equal to 5.24 eV. In addition, the P–T phase diagram of the known Y3Sc2Al3O12 (YSAG) was calculated for the first time. Unlike LSAG, YSAG is stable at fairly high temperatures, reaching values of at least 1500 K. With increasing temperature to 1500 K, the pressure of the phase transition increases slightly to 3.55 GPa, and the monovariant curve of the reaction YSAG↔3YAP+Sc2O3 is represented by an almost straight line.

KW - Density functional theory

KW - Elastic properties

KW - Garnets

KW - LSAG

KW - P-T phase diagram

KW - Thermal conductivity

KW - YSAG

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85194765508&origin=inward&txGid=86592cea1f3f7392bd3ec6b873cd38b7

UR - https://www.mendeley.com/catalogue/c8f0bf61-4a5c-3563-8526-cad9bd56f45a/

U2 - 10.1016/j.commatsci.2024.113124

DO - 10.1016/j.commatsci.2024.113124

M3 - Article

VL - 243

JO - Computational Materials Science

JF - Computational Materials Science

SN - 0927-0256

M1 - 113124

ER -