High-pressure studies on configuration interactions ofPr3+in different hosts

Abstract

High-pressure data of the energy levels of ${\mathrm{Pr}}^{3+}$ in ${\mathrm{LaCl}}_{3}$ and LaOCl are used for the determination of free-ion and crystal field parameters under pressure. In addition to the conventional calculation considering only the ${4f}^{2}$ configuration, the excited configurations ${4f}^{1}{5d}^{1}$ and ${4f}^{1}{6p}^{1}$ under pressure are now taken into account. The inclusion of the excited configurations requires many new parameters. In order to limit the number of parameters that have to be varied under pressure, VUV excitation spectroscopy has been employed. From these measurements, the position as well as the shift of the ${4f}^{1}{5d}^{1}$ configuration is determined as a function of pressure. The effect of the excited configurations on the free-ion parameters is found to be negligible. However, the conventional crystal-field parameters ${B}_{q}^{k}(f,f),$ acting within the ground ${4f}^{2}$ configuration, show distinct changes in their ambient pressure values as well as in their pressure behavior. The difficulties in using crystal-field parameters, derived from parametrizations taking into account only the ${4f}^{2}$ configuration, are elucidated with respect to more extended evaluations.