The substitutional occupation of vanadyl ion in diaquamalonatozinc(II)—single crystal EPR and powder optical studies

Abstract

Room temperature single crystal electron paramagnetic resonance (EPR) studies have been carried out on VO(II) doped diaquamalonatozinc(II) at X-band frequencies. The analysis of the data suggests the position of the vanadyl ion is substitutional replacing zinc ion. The spin Hamiltonian parameters g xx = 1.998, g yy = 1.960, g zz = 1.924 and A xx = 7.40, A yy = 6.63, A zz = 18.27 mT indicate that the symmetry around metal ion is no longer axial due to the substitution position of the impurity. The optical spectrum of the powder sample recorded at room temperature indicates three bands and the percentage of covalency of the metal-oxygen bond has been estimated as 22%. The admixture coefficients and bonding parameters have been calculated correlating EPR and optical data.

Electron paramagnetic resonance and optical study of VO2+-doped zinc ammonium phosphate hexahydrate single crystals

“…Therefore, for practical purposes, the symmetry may be considered to be axial and these equations may be applied for calculating the parameters P, K. The P and K are evaluated for the positive ratio of A /A ⊥ to obtain the best fitted values [44,48], so in our case A and A ⊥ are taken as negative. The constant P is a measure of the radial distribution of the electron wave function and its standard value for a free VO 2+ ion is 0.016 cm −1 [50]. The values of P calculated using equations ( 5) and (6) for VO 2+ at sites I and II in ZAPH are 0.0119 and 0.0104 cm −1 , respectively, which are considerably reduced (about 25 and 35%, respectively) from the free ion value.…”