No abstract

Single crystals and powder EPR spectra of Cu e+ ions in Cs2 Zn(SO 4 )s • 6H2 O were recorded in the temperature range of 4.2-300 K and the g-factor temperature variations were determined. The gz and gy have the values of 2.443 and 2.134, respectively, at the rigid lattice limit below 20 K, and then continuously tend to an average value on heating. This vibronic averaging produced by reorientations of Cu(H 2 O)6-complexes between Jahn-Teller distorted octahedral configurations is described in terms of a two-state SilverGetz model which is known as a good model for diamagnetic non-ammonium Tutton salts. We found, however, that this model is only a crude approximation in Cs2Zn(SO4) s • 6H2O below 150 K. Above this temperature the model works better and describes the vibronic dynamics between the two lowest energy potential wells in the adiabatic potential surface differing in the energy of δ12 = 318(9) cm-1 = 3.7 kJ/mol.

A standard X-band electron paramagnetic resonance cavity has been adapted to measurements under uniaxial stress parallel to the external magnetic field direction. The system is applied to study single crystals under stress up to 100 MPa in the temperature range 100–400 K.