Single crystal EPR study of VO(II) in magnesium potassium phosphate hexahydrate: a case of two substitutional vanadyl ions

Single crystal EPR study of VO(II)-doped magnesium potassium phosphate hexahydrate has been carried out at room temperature. Single crystal rotations in the three orthogonal planes indicate that the paramagnetic impurity has entered the lattice in place of magnesium ions by replacing the equatorial and axial coordinated water molecules. The spin Hamiltonian parameters obtained for the two substitutional sites are: site 1: g1 = 1.9800, g2 = 1.9774, g3 = 1.9296, A1 = 7.25 mT, A2 = 8.09 mT, A3 = 18.69 mT and site 2: g1 = 1.9802, g2 = 1.9765, g3 = 1.9296, A1 = 6.82 mT, A2 = 8.48 mT, A3 = 18.75 mT, respectively. Superhyperfine, from protons of ligand water molecules, has been observed at certain orientations. It has been concluded that VO bond directions of the two substitutional ions are orthogonal to each other.