Theoretical investigations of substitution site and local structure distortion for tetragonal Cr~(2+) ion in AgGaSe2: Cr~(2+) compound

摘要

In this paper, the substitution site and local structure distortions for Cr~(2+) ion doped into AgGaSe2 crystal are studied by diagonalizing the full energy matrix within a strong-field basis. Our calculations show that the local structure has an expansion distortion when Ga~(3+) is substituted by Cr~(2+) ion, while has an expansion distortion along bond-length direction and a compression distortion along angular direction when Ag~+ is substituted by Cr~(2+) ion. From ZFS parameter calculations, the local lattice structure parameters R=2.59 Å and θ=56.16~° for Cr~(2+) occupying Ga~(2+) site, and R=2.85 Å and θ=55.97° for it occupying Ag~+ site are determined.