Effect of nano-sized SiO2 on the optical properties of YVO4:Eu3+ phosphors

In this paper, YVO₄: 1%Eu³⁺ phosphor was synthesized via solid state method at 1100 °C. Then TEOS was used as the source of silica, to coat the phosphors, using sol–gel approach. HRTEM analysis confirmed the formation of adhered and smooth coating layer with the thickness of 40–50 nm. From the experiments and characterizations, we found that although the amounts of added SiO₂ to the phosphors were not remarkable, but it resulted in enhancement of photoluminescence properties. Interestingly, under the excitation wavelength of 310 nm, the efficiency of the phosphors increased by about 20%. Also, a considerable effect of coating layer on decrease in surface oxygen vacancies was studied using ESR technique. Finally it was found that SiO₂ coating of YVO₄:Eu³⁺ phosphors, improves both chemical stability and thermal quenching, effectively.