文摘
In this work, we first investigate the relationship between temperature and lattice parameters by means of Rietveld refinement and then demonstrate its impact on the luminescence peak position of Eu2+ in Sr8(Si4O12)Cl8. It is found that with increases in temperature, lattice expansion takes place without significant distortion of the coordination around Eu2+. As a result, the crystal field splitting of the Eu2+ 5d state decreases. At the same time, with the experimental data of the full width at half-maximum of Eu2+ emission at different temperatures and the infrared spectrum, the effective phonon frequency is evaluated and the main vibration motions are determined using first-principles calculation. Due to the high light yield under X-ray excitation and the excellent thermal stability of luminescence intensity and decay, a further optimized sample Sr7.7Eu0.3(Si4O12)Cl8 could be a potential scintillation material.