Luminescence, emission spectra and hydrogen content of crystalline Lu₂SiO₅:Ce³⁺

Abstract

Thermally stimulated luminescence and emission spectra of cerium-doped Lu₂SiO₅ have been measured in the temperature interval 10K ⩽ T ⩽ 310K. Eight glow peaks occur with the most intense peak exhibiting a maximum at 306 K. Data analyses show that the peaks generally obey first-order kinetics with thermal activation energies ranging from 0.085 to 0.907 eV. The relatively short lifetime (160 s) of the intense glow peak at 306 K implies that it does not make a significant contribution to the long-lived room-temperature afterglow routinely observed in this phosphor. Spectral emission of the glow peaks is dominated by Ce³⁺ de-excitation, although additional emission due to trace amounts of Sm³⁺ is observed for T < 72 K. Elastic recoil detection measurements in nominally undoped and cerium-doped Lu₂SiO₅ show that the doped specimen contains 3.5–4.0 times more hydrogen within the first 300 nm of the surface than does the undoped sample. However, spectral emission associated with surface hydrogen defects was not observed. Oxygen vacancies, which trap one or more electrons, are proposed as the most likely defect sites in Lu₂SiO₅. Perturbations of the six- and seven-oxygen-coordinated sites produce a multipeak glow curve with various activation energies and frequency factors. The glow peaks are intrinsic to the C2/c-structured lattice and are independent of the particular rare-earth dopant ion.