Possible Hosts for Quadruply Ionized 3d(N) Transition Metal Ions: Na2TiSiO5,Y2SiBe2O7, Bi4X3O12, and Bi12XO20 (X = Si, Ge)

摘要

This report provides the crystal-field splitting of Cr4+ in the host materialsNa2TiSiO5 Y2SiBe2O7, Bi4X3O12, and Bi12XO20. The strength of the crystal field is estimated by evaluating the coefficients of a multipole expansion of the crystal field for the Ti, Si, or Ge site and using empirical values of the radial integrals, . With the exception of the Ti site in Na2TiSiO7, the Si or Ge sites(D2d or S4 symmetry) are, to a certain degree, approximately tetrahedral. In the material Bi12Xo20 the X site (Ge or Si) has the cubic symmetry T. Estimated values of the parameters for the quadruply ionized 3dn electronic configurations are given for X=Ge. The energy levels are calculated with and without the spin-orbit interaction.