Site determination of vanadyl impurity in cadmium sodium sulphate hexahydrate: single crystal EPR and optical studies

Abstract

Electron paramagnetic resonance (EPR) and optical studies of VO(II) doped cadmium sodium sulphate hexahydrate (CSSH) are carried out at room temperature. The EPR spectra, recorded in the three orthogonal planes, indicate that the paramagnetic impurity has entered the lattice site both in substitutional and interstitial positions. The spin Hamiltonian parameters, calculated from the spectra for the two sites, are: site I: gxx=1.984, gyy=1.975, gzz=1.938; Axx=6.56, Ayy=7.50, Azz=18.61 mT; site II: gxx=1.982, gyy=1.978, gzz=1.940; Axx=6.88, Ayy=7.56, Azz=18.57 mT. The EPR spectrum of the powder sample also reveals the presence of two sites in the host lattice, suggesting that the two sites are chemically and magnetically inequivalent. The optical absorption spectrum exhibits three characteristic bands. Crystal field, tetragonal field, admixture coefficients and bonding parameters are evaluated, which suggest that the complex is fairly covalent in nature.

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

“…Equations ( 2)-( 4), obtained considering |x y as the ground state (discussed later), yield the parameter values as: Dq = 1497, Ds = −2524, and Dt = 940 (in cm −1 ). These values are in agreement with the values reported for a lattice under strong tetragonal distortion (C 4ν symmetry) [46] and compare well with those listed in table 5 for other host lattices [13,17,18,24,[26][27][28][29][30][31][32].…”

“…This indicates that the delocalization of electrons is not large and so the in-plane π-bonding ability of ligands in both sites is poor. The calculated values of P and K match well with those reported in the literature [11,14,17,18,[26][27][28][30][31][32].…”

“…In different crystal field environments, interesting changes in EPR spectra have been found due to vanadyl ions and these changes are reflected in the values and anisotropy of the g and A tensors. Due to this, VO 2+ ions are used extensively in EPR studies as dopants in different lattices [9][10][11][12][13][14][15][16][17][18][19][20] to investigate defect properties, structural changes and host lattice effects on molecular ions. Since the VO 2+ ion shows different types of absorption spectra depending upon the type of site symmetry of the complexes, valuable information can be obtained from electronic spectral data [21][22].…”

EPR and optical studies of VO2+ doped diglycine calcium chloride tetrahydrate single crystals

“…It is also interesting and productive to study the local symmetry and the bonding of the vanadyl complex by correlating EPR and optical absorption data [8][9][10]. EPR and optical studies on VO 2+ ion in a variety of host lattices have been reported [11][12][13][14][15] earlier. The present paper reports the X-band EPR and optical absorption studies on VO 2+ ion in diglycine calcium chloride tetrahydrate (DGCCT) single crystal at room temperature.…”

Electron paramagnetic resonance and optical absorption study of VO2+-doped sodium zinc sulfate tetrahydrate single crystals

“…Vanadyl complexes have been a subject of interest to a number of researchers for many years [4][5][6][7][8][9][10][11][12]. However, little work has been reported on double sulfates of monovalent and divalent atoms other than Tutton salts [13].…”