Paramagnetic Resonance Spectrum of Mn⁺⁺ in NaCl Single Crystal

Abstract

The paramagnetic resonance spectrum of Mn⁺⁺ ions contained in NaCl single crystal with concentrations of 1∼3×10⁻⁴ in mole fraction has been investigated. From the analysis of the spectrum the existence of Mn⁺⁺ –Na⁺ vacancy complex, in which a Na⁺ vacancy is at one of the nearest neighbor positions with respect to the Mn⁺⁺ ion, has been verified at room temperature in crystals quenched from high temperatures. However, this state of Mn⁺⁺ ion is unstable at room temperature, and such complexes diffuse through the lattice to form aggregates of Mn⁺⁺ ions. The ground level splitting parameters of a Mn⁺⁺ ion accompanying a Na⁺ vacancy at one of its nearest neighbor positions have been obtained as follows: D=137.9±1 gauss, E=51.4±0.4 gauss, where D and E represent the parameters in the spin Hamiltonian, D[S_z²–1⁄3·S(S+1)]+E(S_x²–S_y²), in which z axis is in the direction of Mn⁺⁺ –Na⁺ vacancy and y axis along the cubic axis perpendicular to it.