Optical spectroscopy of Ni2+ doped crystals of Zn2SiO4

The polarized 15 K absorption spectra of Zn2SiO4 doped with Ni2+ consist of three-band systems in the near-infrared (NIR) and visible (VIS) spectral regions centered at 4700, 8500, and 16500 cm−1, respectively. In the tetrahedral approximation they are assigned to the d → d transitions 3T1 → 3T2, and 3T1(P), respectively. The spectra are interpreted in terms of a Td → C2v site distortion and analyzed using the angular overlap model. The ligand field parameter 10Dq is 4500 cm−1, and the Racah parameters B and C are 780 and 3630 cm−1, respectively. By the inclusion of spin-orbit coupling in the AOM calculation it is possible to assign the rich fine structure in the origin regions of the 3T1 → 3T2, 3A2 absorptions to Ni2+ ions occupying the two crystallographically inequivalent Zn2+ sites of Zn2SiO4.