Trivalent rare-earth-codoped silicate phosphor materials (Ba_1.3Ca_0.7-SiO₄:xDy³⁺/yEu³⁺) for solid-state lighting

Trivalent dysprosium/europium-codoped silicate phosphors (Ba_1.3Ca_0.7SiO₄:xDy³⁺/yEu³⁺) were prepared as a function of Eu³⁺concentration (x= 0.03 andy= 0.01-0.05). The phosphors showed the averaged crystallite size of ∼37.2 ± 1.3 nm and displayed nano-/micro-scale grains with some void defects. The energy bandgap is about 4.3 eV for co-doped samples and 3.2 eV for the silicate host. The photoluminescence spectra indicated that the presence of Eu³⁺ions enhanced the red light emission, and the emission peaks located at the versatile wavelengths of 482, 577, 592, 614, 652, and 703 nm. Then, the internal quantum efficiencies were estimated by using the Judd-Ofelt model. Resultantly, the best quantum efficiency was ∼74% when the doping concentrations were 3 mol% Dy³⁺and 4 mol% Eu³⁺ions. Finally, the CIE coordinate data exhibited that the emission color could be tuned from white to reddish-orange by changing the Eu³⁺contents, proposing the applicability of Ba_1.3Ca_0.7-SiO₄:xDy³⁺/yEu³⁺phosphors to the solid-state lighting.