Surface and spectral investigations of NaCaVO4:Tb3+: a green component phosphor for WLEDs

Abstract

The successful preparation of Tb³⁺-doped NaCaVO₄ green-emitting phosphor powders via combustion synthesis is presented in this report. X-ray diffraction technique was used to confirm the orthorhombic phase of the prepared samples. Modified Debye–Scherrer analysis was employed for calculating crystallite size. Using X-ray photoelectron spectroscopy, the elemental composition and oxidation states of several elements present in the sample were examined. Four emission bands were identified using photoluminescence spectroscopy, and the strongest band located at 545 nm due to the transition ⁵D₄→⁷F₅ is ascribed to green emission out of the phosphor material with enhanced colour purity when excited by near-UV. Using diffuse reflectance spectra, optical parameters including bandgap, metallization criterion and refractive index were also calculated for all concentrations of Tb³⁺ ions (ranging from x = 0–0.055). For the optimum molar concentration, numerical values of these parameters were estimated to be 3.41 eV, 0.412 and 2.294. Based on the above findings, it was concluded that the title phosphor may be explored as green-emitting component near-UV pumped phosphor for white light-emitting diodes.