Investigation of luminescence spectroscopic characteristics in Eu3+-doped Zn2SiO4 by Judd–Ofelt parameters

Optical properties of a phosphor material depend on the nature of the impurity and the site of occupancy of the dopant in the host matrix. In metal silicates with the general formula M2SiO4, there are two cationic sites and, possibility of three different occupancy sites. The site occupancy of the dopant decides the emission characteristics of such a phosphor material. Herein we report the fabrication and photoluminescence studies of europium (Eu3+)-doped Zn2SiO4 nanophosphor. We show that the site occupancy of the Eu3+ has an influence on the emission spectrum of the luminophore. Phase formation, purity, surface morphological characteristics and particle size of the Eu3+:Zn2SiO4 are characterized by powder X-ray diffraction (PXRD), Fourier Transform Infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The excitation spectra were recorded monitoring emission at 614 nm emission. The photoluminescence emission spectra of Eu3+ in Zn2SiO4 upon excitation at 395 and 465 nm are studied. The emission spectra of the Zn2SiO4: xEu3+ (x = 0.01–0.11) showed series of emission spectra corresponding to electric dipole and magnetic dipole transitions of Eu3+ characteristic f-f transitions. Judd–Ofelt (JO) intensity parameters are calculated to understand the emission behavior of Eu3+ luminophore in Zn2SiO4 phosphor. There is a higher covalency of Eu–O in samples with higher Eu3+ concentration as evident from Ω2 and Ω4 values. Furthermore, the concentration quenching in Zn2SiO4: xEu3+ observed beyond x = 0.05 is dominated by multipole-multipole interaction due to non-radiative transitions. The decay lifetime is also calculated for all the samples monitoring the emission at 614 nm and it shows higher lifetime for the sample with x = 0.05. The CIE color coordinates are also calculated and found to be (x, y = 0.662, 0.338).