Ab initio investigations of electronic structure, optical transparency, and elastic properties in X3Al2Si3O12 (X = Ca, Mg)

Abstract

Abstract A series of ab initio simulations were performed to investigate the electronic, transparent, and elastic properties of Ca 3 Al 2 Si 3 O 12 and Mg 3 Al 2 Si 3 O 12 which have potential applications in lithography optics, lenses and phosphor materials. From the simulated electronic structure and optical properties, we found that the theoretical transmittance of both compounds reaches 90% above 198 nm in the UV region. The bulk modulus and shear modulus of Ca 3 Al 2 Si 3 O 12 were calculated to be 181.41 and 115.84 GPa, respectively. The anisotropy in elastic properties along different crystallographic direction were found greater in Ca 3 Al 2 Si 3 O 12 than that in Mg 3 Al 2 Si 3 O 12 . The distinct dodecahedral coordinated Ca and Mg in the crystal structures result in the maximum Young's modulus existing in different direction, which is along [1 0 0] direction for Ca 3 Al 2 Si 3 O 12 but [1 1 1] direction for Mg 3 Al 2 Si 3 O 12 . Our theoretical investigations provided a basic understanding on the materials design of Ca 3 Al 2 Si 3 O 12 and Mg 3 Al 2 Si 3 O 12 .