Cation distribution and g factors of certain spinels containing Ni ++, Mn++, Co++, Al--, Ga +++, and Fe+++

Abstract

X-ray measurements on NiOAl2O3, MnOAl 2O3, and CoOAl2O3 show that the Ni spinel is almost completely inverted, the Mn partially so, and the Co compound almost completely normal. This information combined with the magnetic susceptibility vs temperature data yields a g-value of approximately 4.0 for both tetrahedrally coordinated Ni++ and for octahedrally coordinated Co++. X-ray measurements indicate that the Ni++ ion also prefers the octahedral site in NiOGa2O3, NiOFe 1.00Al1.00O3, and NiOFe0.25Al 1.75O3.