Synthesis and characterizations of novel Sr2Gd8(SiO4)6O2:Eu3+ oxyapatite phosphors for solid-state lighting and display applications

Abstract

Various concentrations of Eu3+ ions activated oxyapatite structured Sr2Gd8(SiO4)6O2 (SGSO:Eu3+) phosphors were prepared using a citrate sol–gel technique. The structural properties were analyzed by the X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Morphological studies of these phosphors were carried out by the field-emission scanning electron microscopy (FE-SEM). The XRD patterns confirmed the hexagonal crystal form of oxyapatite structure with the space group of P63/m after annealed at 1450 °C, which was also authenticated by the FTIR spectra. The FE-SEM image showed a typical rod-like morphology. The luminescent properties of the SGSO:Eu3+ phosphors were investigated with the help of photoluminescence (PL) and cathodoluminescence (CL) analyses. The PL excitation (PLE) spectra exhibited a charge transfer band in the higher energy region and intense excitation bands in the lower energy region. The main excitation bands in the ultraviolet (UV), near-UV and visible regions showed higher intensities as well as better full width at half maximum values as compared to the commercial Y2O3:Eu3+ phosphors. The PL spectra revealed a stronger emission band with a peak at 613 nm due to the forced electric-dipole transition of 5D0 → 7F2 under different excitation wavelengths, but the SGSO:Eu3+ phosphors showed greater emission intensity more than 4 times when compared with the Y2O3:Eu3+ phosphors under 394 nm excitation. The CL spectra also showed luminescence behavior similar to the PL spectra. Due to the better PL and CL properties, the SGSO:Eu3+ phosphors are expected to have potential applications in solid-state lighting industry.