Room-temperature electron paramagnetic resonance measurements were performed on as-grown single crystals. In the case of Cr3+-doped crystals, signals from Cr3+ centers with monoclinic (ii-II) and orthorhombic (iii-III) symmetries were observed, together with those from the uncompensated tetragonal iii (I-I). On the basis of a spin-Hamiltonian separation analysis, ii-II was attributed to a Cr3+ ion which occupied a Zn2+ site with a vacancy at its nearest Tl+ site. Center-III was attributed to a Cr3+ ion that was associated with a vacancy at the nearest Zn2+ site. Anomalies were found in the separated parameters, b2a(1), for centers II and III, and in b2a(2) for iii-III. These were roughly double the size of those for other layered perovskite fluorides; such as Rb2ZnF4 and K2ZnF4 with various monovalent cations. It was suggested that these anomalies might be due to some effect arising from the nearest- and next-nearest Tl+ ions.

Anomaly in the Fine-Structure Splitting of EPR Spectra of Cr3+ Centers in Tl2ZnF4 Crystals. M.Arakawa, H.Ebisu, H.Takeuchi: Journal of Physics - Condensed Matter, 2002, 14[36], 8613-23