Electron paramagnetic resonance of divalent nickel in ferrous fluosilicate

Abstract

The EPR spectrum of Ni2+ in single crystals of ferrous fluosilicate FeSiF6·6H2O was studied at liquid helium temperatures in the frequency range 14.0–16.5 GHz. The six-line spectrum, associated with six inequivalent Ni2+ sites, was fitted to the spin Hamiltonian H = gβH·S + DSz2 + E (Sx2 − Sy2), with S=1, g=2.255±0.005, D=−(3.05±0.02) cm−1, and E=(0.170±0.001) cm−1. The magnitudes of g and E and the sign of D were deduced, respectively, from the frequency dependence and the temperature dependence of the single line spectrum observed in the parallel orientation. The magnitude of D was obtained from measurements in the perpendicular plane. The perpendicular spectrum showed a sixfold rotational symmetry and consisted of two sets of three lines related by a rotation of (13.0±0.5)° about the c axis.