Defining of the Covalence Parameters in Cs₂NaYCl₆:Eu³⁺ and Cs₂NaEuCl₆ by the Optical Spectra

Abstract

The influence of the excited configurations with the charge transfer on the Stark structure of the multiplets of Eu 3+ ion in the elpasolites was investigated with the help of the modified crystal field Hamiltonian. Cs2NaYCl6:Eu 3+ and Cs2NaEuCl6 crystal systems were chosen as the subjects of our research. The modified Hamiltonian of the crystal field was for the first time applied to the crystal systems activated by Eu 3+ ions and its use has allowed to reduce considerably the root-mean-square deviation and to define the covalence parameters from optical spectra. The convenient algorithm for determination of errors of the modified Hamiltonian parameters is offered.