Single-crystal electron paramagnetic resonance (EPR) study of Mn(II)-doped cobalt ammonium phosphate hexahydrate has been carried out at room temperature. The impurity shows more than 30 line pattern EPR spectra along the three crystallographic axes, suggesting the existence of more than one type of impurity ion in the host lattice. The spin Hamiltonian parameters, estimated from the three mutually orthogonal crystal rotations, are: site 1: g xx = 1.989, g yy = 1.994, g zz = 1.999; A xx = −8.97, A yy = −9.52, A zz = −9.71 mT; D xx = −8.09 mT, D yy = −6.05 mT, D zz = 14.14 mT; site 2: g xx = 1.988, g yy = 2.009, g zz = 2.019; A xx = −9.11 mT, A yy = −9.58 mT, A zz = −9.93 mT; D xx = −6.61 mT, D yy = −6.11 mT, D zz = 12.72 mT. The angular variation studies further reveal that the Mn(II) impurities enter the lattice substitutionally. The other Mn(II) sites which are at interstitial locations are difficult to follow due to their low intensity. The variation of zero-field splitting parameter with temperature indicates no phase transition. The observation of well-resolved Mn(II) spectrum at room temperature has been interpreted in terms of 'host spin-lattice relaxation narrowing' mechanism.

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.

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Identification of doped paramagnetic vanadyl impurity in dipotassium diaquabis(malonato-κ 2 O,O′) zincate dihydrate single crystal using EPR and optical techniques, Single crystal electron paramagnetic resonance (EPR) spectroscopic investigation of VO(II) doped dipotassium diaquabis(malonato-κ 2 O,O ) zincate dihydrate has been carried out at X-band frequencies at 300 K. Single crystal, rotated along the three orthogonal crystallographic axes, has yielded spin Hamiltonian parameters g and A as g xx = 1.978, g yy = 1.972, g zz = 1.936 and A xx = 7.12, A yy = 6.73, A zz = 18.24 mT, respectively. These spin Hamiltonian parameters reflect a slight deviation from axial symmetry to rhombic, which is explained by the interstitial occupation of vanadyl ions. The isofrequency plots and powder EPR spectrum have been simulated using the calculated spin Hamiltonian parameters. The percentage of metal-oxygen bond has been estimated to be 20%. The admixture coefficients and bonding parameters have also been calculated by combining the EPR data with optical data.

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