Study on photoluminescence and thermoluminescence properties of UV-irradiated CaSrAl2SiO7:Ce3+ phosphors

Abstract

This paper reports synthesis of CaSrAl2SiO7:Ce3+ phosphors via traditional high temperature solid state reaction method. The phase analysis of the phosphors was carried out using powder X-ray diffraction (XRD) technique which indicates that all these compounds are of single phase of CaSrAl2SiO7 with tetragonal crystal structure. Average grain size of the phosphor was determined by using Scherrer formula. The photoluminescence (PL) study was carried out using spectrofluorophotometer. PL Excitation (PLE) spectra consist of two peaks at around 253 and 290 nm. CaSrAl2SiO7:Ce3+ emits strong violet emission located at 418 nm when excited with 290 nm. Emission is associated with 5D→4F transition of Ce3+ ions. Thermoluminescence (TL) properties of UV-irradiated phosphor were measured. Effect of different heating rates on TL glow curve was recorded and 5 °C/s is found to be optimum heating rate. There is no shift in glow peak position with increase in UV-irradiation time. TL intensity increases with increase in UV exposure time up to 35 min and then saturates. To analyse kinetic study, glow curve was deconvoluted into four different traps and their activation energies were determined by using peak shape method. Concentration dependence on PL and TL was investigated; concentration quenching in PL occurs at 1 mol% of Ce3+ and quenching in TL arises at 0.5 mol% of Ce3+. TL spectra and decay characteristic were also carried out. This paper deals with possible mechanism of PL and TL.