Crystal structure of Sr6Y2Al4O15: XRD refinements and first-principle calculations

The ternary oxide phase Sr6Y2Al4O15 (SYA) was synthesized and the crystal structure was determined by using the X-ray powder diffraction data. Structure of the phase can be considered as an oxygen-deficient perovskite Sr(Y1/3Al2/3)O2.5 and has a monoclinic C2 (S.G. No. 5) unit cell with the unit cell parameters: a=17.597(1) Å, b=5.7408(1) Å, c=7.6860(1) Å, β=90.7659(3)°, Vcell=776.37(1) Å3, Z=2. By bond parameter analysis and first-principle calculations, we confirmed the reasonability of our crystal structure model. According to the calculated band structure, SYA has an indirect band gap ∼4.3 eV and a direct band gap ∼4.4 eV, which is wide to be transparent to UV and visible lights. We also synthesized other rare-earth isomorphs Sr6Ln2Al4O15 (Ln=Tb, Dy, Ho, Er, Tm, Yb and Lu) and obtained their cell parameters.