EFFECT OF PRESSURE ON ELECTRON STATE OF EU3+ IN GD2O2S

The fluorescence spectra of Eu3+ in Gd2O2S have been measured at room temperature and under pressures within the range of 0-14.8 GPa. The cr ystal-field levels of the F-7(0-6) and D-5(0-6) multiplets of the Eu3 ion have been determined at different pressures. With increasing pres sure the crystal-field splittings of the F-7(2-5) and D-5(2) multiplet s increase; however, the splittings of F-7(1) and D-5(1) decrease. The crystal-field parameters B-q(k) and the crystal-field strength parame ter S-t versus B-q(k) were also determined at different pressures. In the pressure range up to 14.8 GPa, S-t increases by 11%. Under pressur e, the barycenters of the F-7(1-2) and D-5(0-2) multiplets descend, th e Slater parameter F-2 and the spin-orbit coupling parameter zeta redu ce. The symmetry-restricted covalency mechanism plays a main role in t he reduction of F-2 and zeta. (C) 1998 Elsevier Science B.V. All right s reserved.