High Pressure EPR Studies of Nickel Complexes

摘要

Two nickel compounds NiSiF_6·6H_2O and NiSnCl_6·6H_2O have been studied by electron paramagnetic resonance method under pressure up to 600 MPa and in the temperature range 80 -400 K. The spectrum of nickel fluosilicate in low temperatures shows a considerable narrowing of the EPR line when the zero-field splitting parameter D reaches zero, and the presence of a certain range of temperatures and pressures in which D = 0. For nickel chlorostannate hexahydrate the pressure dependence of D: (partial derivD/partial derivp)_T = (11.2 +-1.2)·10~(-4) cm~(-1)/MPa, is more pronounced than for nickel fluosilicate, which is explained by high anisotropy of compressibility of this compound. The difference in behaviour of D-parameter for both compounds in the vicinity of D = 0 is discussed.