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

The magnetic susceptibility as well as the optical excitation and luminescence spectra of three samples of alpha-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 D-3d Site has been used to fit the optical data. The best-fit parameters of the tiospinel crystal are B-20 = 4800, B-40 = 32 500, B-43 = -28 500, F-(2) = 58 800, F-(4) = 40 500 and xi(D) = 300 cm(-1). The computational procedure used gives excellent agreement between the experimental and calculated energy levels of the Cr3+ ion in the alpha-ZnAl2S4 matrix. (C) 2000 Published by Elsevier Science B.V. All rights reserved.