The X-band electron paramagnetic resonance spectra of Mn2+-doped monocrystals at room temperature were analyzed in terms of a spin-Hamiltonian of C3 symmetry. Experimental data were interpreted by using the superposition model in a 2-fold manner. Firstly, the zero-field splitting parameters (b20, b40, b43, b4-3) were predicted. Although the results for b20 were inconclusive, those for the major fourth-order term, |43| = [(b43)2 + (b4-3)2]½ exhibited closer agreement with experiment; assuming the presence of Mn2+ at a Nb site. Secondly, crystal field parameters were obtained from the superposition model by using 2 sets of available structural data. Diagonalization of the crystal field Hamiltonian within the whole 3d5 configuration yielded the theoretical zero-field splittings. The results for Mn2+ at a Nb site agreed better with the experimental data than did those for Mn2+ at a Li site. It was concluded that superposition model analyses of the observed electron paramagnetic resonance spectra indicated that the spectra were best attributed to Mn2+ ions at Nb sites.

T.H.Yeom, S.H.Choh, Y.M.Chang, C.Rudowicz: Physica Status Solidi B, 1994, 185[2], 417-28