Preparation and luminescent properties of color-adjustable La1-x-ySiBO5: xTb3+, yEu3+ phosphor for NUV-LEDs

A series of La1-x-ySiBO5:xTb3+, yEu3+ phosphors was synthesized through high-temperature solid-state reaction. The crystal structure, morphology, and luminescence properties of the phosphors were characterized by employing X-ray diffraction, scanning electron microscopy, photoluminescence, photoluminescence excitation and fluorescence lifetime measurements. Results show that the excitation spectra of La1-xSiBO5:xTb3+ and La1-ySiBO5:yEu3+ overlap at 300-400 nm, and the La1-x-ySiBO5:xTb3+, yEu3+ phosphors emit yellowish green (530-560 nm) and red (580-650 nm) light under 377 nm excitation. When x = 0.05 and y increases from 0.005 to 0.05, the emission intensity of Tb3+ decreases gradually, whereas that of Eu3+ increases gradually. This trend indicates energy transfer from Tb3+ to Eu3+ and color change from green to yellow and then red. The fluorescence lifetime test further confirms energy transfer from Tb3+ to Eu3+. The prepared LaSiBO5:Tb3+, Eu3+ phosphors exhibit effective tunable emission and near ultraviolet excitation and thus have potential applications in White-LEDs.