Luminescence of Li2W1-0.05Mo0.05O4 crystal under X-ray excitation

Abstract

Luminescence of Li2W1-0.05Mo0.05O4 crystal was investigated under X-ray excitation. A broad emission band with a maximum at ∼530 nm was measured at temperature 8 K, two phosphorescence exponential components with decay constants 15 s and 380 s were observed after X-ray irradiation at the low temperature. Thermally stimulated luminescence (TSL) was recorded in Li2W1-0.05Mo0.05O4 crystal after X-ray irradiation at 8 K. Seven clear TSL peaks in the temperature region 8–150 K were observed. An equidistant character of the TSL peaks can be explained by oscillatory pattern for thermal-delocalization energies from traps. A delocalization energy value for the most intensive TSL peak at 21 K is calculated. It allowed estimation of the main parameters of the traps in the crystal (delocalization energies and frequency factors). The correspondence between the traps energy and the integer value of the crystal-lattice oscillatory-quanta energy indicates the direct tunneling of a charge carrier into an excited state of the recombination center located near the trap.