Effects of microwave-assisted hydrothermal treatment and beta particles irradiation on the thermoluminescence and optically stimulated luminescence of SrMoO4 powders

Abstract SrMoO4 powders, produced by co-precipitation, are investigated employing thermoluminescence (TL) and optically stimulated luminescence (OSL). The effects of microwave-assisted hydrothermal (MAH) treatment, beta particle irradiation, and thermal treatment are studied to understand their role on defect density and location in the band-gap. The powder X-ray diffraction showed that the SrMoO4 powders crystallize in a tetragonal structure. The raman studies confirmed the presence of active vibration modes characteristic of molybdates, whereas the Fourier Transformed Infrared (FTIR) data exhibit the symmetric and asymmetric stretch vibrations. The trapping depth energies, determined from TL glow curves, range from 0.9 eV to 1.95 eV. The TL data show that the MAH treatment decreases the defect density and favors the formation of defects with lower activation energies. The residual TL signal shows the formation of shallower traps with a glow peak occurring at lower temperatures. The OSL emission only taken place for samples submitted to heating cycles and depends on the heating rate. These results indicate that shallow traps induced by thermal treatment are responsible for the OSL signal. The shape and intensity of the OSL curve depend on the number of heating cycles and on the heating rate, revealing that thermal treatment has a profound influence on this emission. The OSL signal for MAH-treated SrMoO4 samples subjected to thermal treatment increases linearly with beta irradiation dose. The results give insight that SrMoO4 phosphors may have potential applications in the design of a radiation sensor.