Synthesis, crystal structure and luminescent properties of titanium(IV)-doped calcium borostannates, CaSn1−xTix(BO3)2

Compounds in the CaO–B2O3–SnO2 system were prepared by solid-state reaction at 700–1100 °C in air. The phase relations in this system were investigated by powder X-ray diffraction (XRD). A previously reported calcium borostannnate, CaSn(BO3)2 (rhombohedral, R3¯ (No. 148), Z = 3, a = 4.85872(3), c = 16.07750(11) Å), was synthesized in this system. Titanium(IV)-doped solid solutions, CaSn1−xTix(BO3)2 (0 < x < 0.30), were prepared, and their cell parameters were refined by the Rietveld method. A broad blue-green emission at 489 nm was observed in the photoluminescence (PL) spectra of CaSn1−xTix(BO3)2. The maximum emission intensity was measured for CaSn0.99Ti0.01(BO3)2. The PL excitation peak of CaSn0.99Ti0.01(BO3)2 was observed at 263 nm (4.71 eV).