Bi3+-doped Ba2Y1−xLuxNbO6:Bi3+ (0 ≤ x ≤ 1.0) solid solution phosphors: tunable photoluminescence and application for white LEDs

In this work, we use the conventional high temperature solid-state reaction to prepare Bi3+-doped Ba2Y1−xLuxNbO6:Bi3+ (0 ≤ x ≤ 1.0) solid solution phosphors. To study the Lu3+ content-dependent structural evolution and photoluminescence (PL) properties of the samples, the powder X-ray diffraction (pXRD), density functional theoretical (DFT) calculations, UV–visible diffuse reflectance and PL spectra are used. We find that all the phosphors are double-perovskite structural phase with a cubic space group of $${\rm{Fm}}{\bar{3}}{\rm{m}}$$ , and the XRD positions shift to higher diffraction angle with the increase in Lu3+ content. The emission positions of the samples tune from 447 to 493 nm, which are due to the crystal field modulation around the Bi3+ ion. Among the obtained samples, the Ba2Y0.7Lu0.3NbO6:Bi3+ shows the best quantum efficiency (QE) of 57%. By using the optimal Ba2Y0.7Lu0.3NbO6:Bi3+ solid solution phosphor, the red-emitting CaAlSiN:Eu2+ phosphor, and a commercial 365 nm UV LED chip, we have fabricated a white LED device with the CIE coordinates at (0.378, 0.373), colour temperature (CT) of 3513 K, colour rendering index (CRI) of 67.1 and luminous efficiency of 39 lm W−1.