Magnetic susceptibility and luminescence of α-ZnAl2S4 tiospinel doped with chromium Original Research Article

The magnetic susceptibility as well as the optical excitation and luminescence spectra of three samples of α-ZnAl2S4 tiospinel doped with Cr at various concentrations have been measured in the temperature range 77–300 K. The susceptibility has allowed us to estimate the concentration of Cr in the samples studied as lying in the range 0.01–0.06 at.%. Crystal-field theory, including spin–orbit coupling and the trigonal crystal field of the D3d site has been used to fit the optical data. The best-fit parameters of the tiospinel crystal are B20=4800, B40=32 500, B43=−28 500, F(2)=58 800, F(4)=40 500 and ξD=300 cm−1. The computational procedure used gives excellent agreement between the experimental and calculated energy levels of the Cr3+ ion in the α-ZnAl2S4 matrix.