EPR STUDY OF STRUCTURE OF CSPBCL3

Studies of the EPR of dilute Mn2+ in CsPbCl3 have been carried out over the temperature range 77°-340°K. Crystalline phase changes as indicated by changes in the Pb site symmetry were evident at 320°K (46.5°C) and 185°K. The first of these has been reported previously while the latter is apparently a new observation. Between 185°and 320°K, the EPR spectra can be assigned to two and possibly four crystallographically equivalent sets of magnetically inequivalent sites, the spectra of the ith set derivable from the spin Hamiltonian Hi= gβH·S+Di[Sz2-13S(S+1)]+E i(Sx2-Sy2)+16a i(Sx4+Sy4+S z4)+ASzIz+B(SxI x+SyIy). Typical values of the crystal field parameters are: A = -87.5 G, B = -86.5 G, and a≈1 G; all sensibly temperature independent, while D and E are temperature dependent. For example at 195°K, D1,2,3,4=45 G and E1= -E2=7.2 G, E 3=6.4 G, and E4= -5.0 G. Both D and E tend continuously to zero at 320°K. Thus, the individual site symmetries are evidently orthorhombic and the overall crystal symmetry is apparently orthorhombic or nearly so. Some discussion of possible crystal space groups is included. © 1970 The American Institute of Physics.