Energy Spectrum of YAG:Cr3+ and Thermal Shifts of Its R Lines

摘要

＜正＞ Traditional ligand-field theory has to be improved bv taking into account both "pure electronic" contributionand electron-phonon interaction one （including lattice-vitbrational relaxation energv）. By means of improved ligand-fieldtheory, R~1, R~2, R3′, R2′, and R1′ lines, U band, ground-state zero-field-splitting （GSZFS） and ground-state g factors aswell as thermal shifts of R1 line and R2 line of YAG:Cr3+ have been calculated. The results are in very good agreementwith the experimental data. In contrast with ruby, the octahedron of ligand oxygen ions surrounding the central Cr3+ion in YAG:Cr3+ is compressed along the [111] direction. Thus, for YAG:Cr3+ and ruby, the splitting of t23 4A2 (or t23 2E)has opposite order, and the trigonal-field parameters of the two crystals have opposite signs. In thermal shifts of R1 andR2 lines of YAG:Cr3+, the tetnperature-dependent contributions due to EPI are dominant.