Preparation, crystal structure and photoluminescence of garnet-type calcium tin titanium aluminates

Colorless and transparent single crystals of Ca3Sn2.2Ti0.8Al2O12, which emit blue–white light under ultraviolet light, were prepared by heating a mixture of oxides and calcium carbonate with a calcium and aluminum-rich composition at 1500 °C. Single crystal X-ray diffraction revealed that the crystal structure is the garnet-type with a cubic cell parameter (a=12.5309(3) Å) and the space group, Ia 3¯d (R1=0.0277, wR2=0.0663, and S=1.367 for all data). The structural formula is presented as Ca3[Sn0.96Ti0.04]octa[Al0.67Ti0.24Sn0.09]tetraO12. Polycrystalline solid solutions of Ca3Sn3−xTixAl2O12 were prepared by solid state reaction in air at 1370 °C with nominal titanium contents from x=0.6 to 1.4. The refined unit cell parameter decreased with increasing x. A broad blue–white emission with a peak wavelength of 465 nm was observed for the solid solutions at room temperature.