Crystal field effects and electron–phonon interaction in K 2LiAlF 6:Cr 3+

Abstract

The crystal field effects and electron–phonon interaction in K 2LiAlF 6:Cr 3+ elpasolite crystal were studied using the exchange charge model (ECM) of crystal field and harmonic approximation of lattice vibrations. The crystal field parameters (CFP) and energy level scheme for the [CrF 6] 3− cluster were calculated. As a further application of the ECM, the crystal field strength 10 Dq was studied for different “impurity ion–ligand” distances R. By fitting these values to the power law 10 Dq≈ R − n of coordinate R, the value of n was obtained as 4.56796. Several physical quantities (such as the electron–vibrational interaction constants, Stokes shifts, Huang–Rhys factors and Jahn–Teller stabilization energy) associated with the two normal vibrational modes a 1 g and e g of the [CrF 6] 3− complex coupled with the Cr 3+ electronic states, were calculated. The obtained results are compared with experimental data and discussed.