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 _z ² -1/3· S ( S +1)]+ E ( S _z ² - S _y ² ), in which z axis is in the direction of Mn ⁺⁺ –Na ⁺ vacancy and y axis along the cubic axis perpendicular to it.