Correlation of Zero Field Splittings and Site Distortions V. Mn in Cs2Zn3S4

Dedicated to Professor A Ifred Klemm on the occasion of his 70th birthday In platelets of Cs2Zn3S4 with about 4% of the Zn substituted by Mn two nonequivalent centers of isolated Mn + were observed in addition to a broad EPR signal near g = 2 which is assigned to clusters of interconnected MnS4 units. The fine structure and hyperf ine structure parameters for the single-ion centers (all in units of 1CT cm ) are: b°2 = 3 1 8 . 3 ± 3 ; ^ = 2 1 0 . 3 ± 2 ; Ay = 62.7; A. = 63.6 ± 0.8; b2 = — 890 + 18; ^ = 7 4 3 + 36; ^ = 6 0 . 6 ; Az = — 61.4 ± 0.8; for centers I and II, resp. Center II arises f rom Zn sites of C 2 site symmetry while for center I assignment to either one of two sites with D 2 site symmetry is possible. The larger hyperfine splitting constants as well as the superposition analysis favor the larger sites which are not occupied by Zn, but are partly occupied in the analogous Mn (and Co) compounds. Superposition analysis yields the same value of + 0.12 ± 0.02 cm" ' for the intrinsic zero field splitting parameter b2 of the bridging MnS4 units in both sites. g: is significantly higher than the free ion value indicating a higher degree of covalency than in Cds and CdGa 2 S 4 .