The electron paramagnetic resonance of the VO2plus;ion in methyl ammonium gallium alum single crystals has been studied. It is observed that the VOplus;2ion substitutes for the Ga3plus;ion and forms a VO(H2O)52plus;complex, a distorted octahedron with a H2O vacancy along VO bond direction. The octahedron cubic axes are found to be displaced from crystallographic lang;001rang; axes by 9deg; in 110 plane. The EPR results suggest that the host alum probably belongs tobgr;type in which the presence of VO2plus;twists the octahedron cubic axes by about 9deg; from the crystallographic lang;100rang; axes. Optical absorption studies confirm the formation of VO(H2O)52plus;. By correlating the EPR and optical absorption data, the covalency rates ofsgr;bonding between the vanadium atom and equatorial ligands and of thepgr;bonding between vanadium atom and the vanadyl oxygen have been estimated.
展开▼
