Phase Transition Study of Zn(BF₄)₂6H₂O by EPR of Diluted Ni²⁺ between 98 and 298 K

抄録

EPR of Ni²⁺ diluted in single crystal of Zn(BF₄)₂6H₂O was recorded between 98 and 298 K. The thermal variations of the spin Hamiltonian parameters g_⁄⁄, g_⊥ and D, and the linewidth of the spectra showed anomalous behavior when compared with previous work in the isomorphous Ni(BF₄)₂6H₂O. The anomalies are attributed to a phase transition of second order with T_c≅181 K. D varies linearly with temperature and the linewidth as ΔH=a+bT² similar to verified previously in the Ni compound. The phase transition occurs with a change in the coefficients of these laws. From the linewidth, a spin-lattice relaxation time T₁ is determined as 10⁻⁹ to 10⁻¹⁰ s.