Influence of calcination temperature on the luminescent properties of Eu³⁺ doped CaAl₄O₇ phosphor prepared by Pechini method

Motivated by the need for new phosphor for white light emitting diode (WLED) applications, CaAl₄O₇ phosphors activated by Eu(3+) rare earth ion was synthesized using the Pechini method at different calcination temperatures. The crystal structure and luminescent properties were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), UV-Vis diffuse reflectance spectroscopy (DRS), and photoluminescence spectroscopy (PL). The XRD and SEM patterns confirm the presence of a single grossite monoclinic phase (311) and the particles exhibit good crystallinity and the particle size varies with calcination temperature. Absorption peak of FT-IR shows the decomposition of citrate ethylene glycol complex and the formation of CaAl₄O₇:Eu(3+) phosphor. Diffuse reflectance spectra indicate an absorption in the UV-region. The photoluminescence excitation spectrum exhibited a broad band covering from 340 to 420 nm with a sharp band at 395 nm. CaAl₄O₇:Eu(3+) phosphor excited by near UV (395 nm) light showed a strong red emission at 611 nm. The emission band is due to f-f transitions within the 4f(6) configuration of Eu(3+) ions, respectively. The photoluminescence properties were found to be strongly dependent on the calcination temperature and the PL properties are superior for sample calcined at 950 °C.