Effects of beta particles irradiation and thermal treatment on the traps levels structure and luminescent properties of BaMoO4 phosphor

Molybdates compounds have been the subject of intense research due to their broad range of potential technological applications. This paper reports the influence of defects in optical and structural properties of barium molybdate (BaMoO4) using a wide range of characterization techniques. The effects of beta particles irradiation and heat treatment are studied to understand their role in defect generation or transformation. Raman and Fourier transform infrared spectroscopy (FTIR) spectra show remarkable changes with irradiation dose and heating rate. The analysis of these data suggests that irradiation with beta particles preserves the interaction on MoO4 clusters, whereas heat treatment changes the structural order, leading to an increase of the site symmetry density. ESR measurements, performed at room temperature, reveal that the defect concentration significantly increases after heat treatment of irradiated samples. An intensity reduction of Phototoluminescence (PL) and Thermoluminescence (TL) emissions are noticeable with increase of radiation dose, probably associated with reduction in the number of active luminescent centers and increase of non-radiative transitions probability. Trapping activation energies determined from TL glow curves range from 0.9 eV to 1.95 eV. This study points that blue and green emissions arise likely due to radiative recombination through localized defect states. (AU)