摘要： Double perovskite antimonates of the type BaLaMSbO6 (M=Mg, Ca) were synthesized by standard solid state route. The compounds were characterized by X-ray diffraction and the crystal structure was refined using Rietveld method. BaLaMgSbO6 and BaLaCaSbO6 crystallized in monoclinic (I2/m) and (P21/n) space group respectively. In both the compounds, La occupied A-site of perovskite, which is 12-coordinated as compared to Ba2LaSbO6 where La ion shifts to B-site octahedral coordination due to larger size of Ba as compared to Mg and Ca. The samples were further characterized using FTIR and the frequency of the octahedral vibration is correlated to the electronegativity of the B-site ions. Photoluminescence study of the title compounds and Ba2LaSbO6 was also studied upon doping with 2 atom% Eu3+ ion, which confirmed that Eu3+ occupies distorted 12-coordinated A-site in BaLaMSbO6 (M=Mg, Ca) and symmetrical octahedral B-site in Ba2LaSbO6. Further, the emission spectrum due to each Eu3+ ion at different crystal site was successfully isolated by TRES study. This enables to understand the structural differences of these compounds. This site selective occupancy of Eu3+ ion also has a direct impact on the light emission, which was found to change from orange to red in a dark room in the order Ba2LaSbO6:Eu → BaLaCaSbO6:Eu → BaLaMgSbO6:Eu. Such study will have high impact in designing new commercial Eu3+ ion doped phosphor materials and tailoring of their optical properties.