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 Bi 3+ -doped Ba 2 Y 1− x Lu x NbO 6 :Bi 3+ (0 ≤ x ≤ 1.0) solid solution phosphors. To study the Lu 3+ 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 Fm 3 ¯ m , and the XRD positions shift to higher diffraction angle with the increase in Lu 3+ content. The emission positions of the samples tune from 447 to 493 nm, which are due to the crystal field modulation around the Bi 3+ ion. Among the obtained samples, the Ba 2 Y 0.7 Lu 0.3 NbO 6 :Bi 3+ shows the best quantum efficiency (QE) of 57%. By using the optimal Ba 2 Y 0.7 Lu 0.3 NbO 6 :Bi 3+ solid solution phosphor, the red-emitting CaAlSiN:Eu 2+ 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 .