EPR DATA ON PROPERTIES OF PARAMAGNETIC-IO NS CO2-CENTER-DOT-6H(2)O INPERMANENT AND PULSED MAGNETIC-FIELDS - HIGH-PRESSURE EFFECT(, NI2+, AND FE2+ IN FESIF6)

The properties of the ground states of impurity ions Co2+ and Ni2+ and host crystal ions Fe2+ in ferrous fluosilicate hexahydrate are studie d. It is found that the low-symmetry phase of the crystal displays six inequivalent centres corresponding to three types of domains. The ang le between the C-3 axis of the crystal and the main magnetic axis is 3 .6 degrees For Co2+ ions, 4 degrees For Fe2+ ions and 1.7 degrees for Ni2+ ions. The high-pressure experiments suggest that in the high-pres sure phase the sign of zero field splitting of the spin multiplet chan ges and the ground state of the Fe2+ ions is a magnetic doublet \+/-2] with g = 2.35. It is also shown that the relaxation processes in ferr ous fluosilicate hexahydrate are mainly due to the interaction with th e Fe2+ ions involving their excited slates and are much more efficient that the intrinsic relaxation of the impurity ions.