Pressure-Induced Shift of R-Line of MgO:Cr ³⁺ with Electron-Phonon Interaction Effect

Abstract

By means of improved ligand-field theory, the ``pure electronic" pressure-induced shift (PS) and the PS due to electron-phonon interaction (EPI) of R-line of MgO:Cr3+ have been calculated, respectively. The calculated results are in very good agreement with the experimental data. The behaviors of the pure electronic PS of R-line of MgO:Cr3+ and the PS of its R-line due to EPI are different. It is the combined effect of them that gives rise to the total PS of R-line, which has satisfactorily explained the experimental results. The comparison between the feature of R-line PS of MgO:Cr3+ and that of R1-line PS of ruby has been made.

Improved Ligand-Field Theoretical Calculation of R-Line Pressure-Induced Shift of MgO:V 2+

“…The PS without EPI is calculated by a theory of PS of energy spectra (e.g., see Refs. [5] and [7] and therein cited references). According to the theory, the expressions of B, C (Racah parameters), Dq (cubic-field parameter), ζ and ζ (spin-orbit coupling parameters) as functions of χ (χ = R/R 0 , where R 0 and R are the local interionic distances around Cr 3+ at normal pressure and pressure P , respectively) are given as follows:…”

“…The value for f may be taken as 0.6 (see Refs. [5] and [7] and therein cited references). As was mentioned in…”

“…For MgO:V 2+ , it is found that the contributions of the second-order and higher terms in H int are negligible (see Refs. [5], [6], and [11]).…”

“…In Refs. [3] ∼ [5], it was demonstrated that traditional ligand-field theory has to be improved by taking into account both pure electronic contribution and EPI one. Of course, for PS of R line, it consists of the two contributions, too.…”

“…Thus, it is necessary to carry out the theoretical calculation and analysis of R-line PS of MgO:V 2+ by using the improved ligandfield theory presented in Refs. [3] ∼ [5].…”