ELECTRON PARAMAGNETIC RESONANCE OF TETRAVALENT MANGANESE IONS AT TETRAGONAL AND OCTAHEDRAL SITES IN MGO

A paramagnetic resonance spectrum of tetragonal symmetry due to Mn4+ ions in MgO has been observed. The spin-Hamiltonian parameters are gII=1.99310.0002, g=1.99400.0002, AII=(-71.10.2)×10-4 cm-1, A=(-70.60.1)×10-4 cm-1, and D=(-528.70.7)×10-4 cm-1. The departure from octahedral symmetry is attributed to the presence of a positive-ion vacancy at the first cation site on the tetragonal axis, thus forming the arrangement 0-Mn2+-0-[=], where only deviations from the normal lattice charge are shown. The spectrum from octahedrally coordinated Mn4+ ions has been observed in a powder sample of MgO; here the spin-Hamiltonian parameters are g=1.99410.0002 and A=-(70.820.10) ×10-4 cm-1. The hyperfine fields at the nuclei of the 3d3 ions V2+, Cr3+, and Mn4+ in MgO are found to be almost identical. © 1969 The American Physical Society.