Electron paramagnetic resonance, optical transmission spectra and DC conductivity studies of vanadyl-doped alkali halide borate glasses

• Published in: Physica. B, Condensed matter Vol. 334; no. 3; pp. 347 - 358
• Main Authors: Khasa, S, Seth, V.P, Gahlot, P.S, Agarwal, A, Krishna, R.M, Gupta, S.K
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.07.2003; Elsevier
• Subjects: Chloroborate glasses; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Conductivity of specific materials; DC conductivity; Disordered solids; Electron paramagnetic resonance and relaxation; Electronic transport in condensed matter; EPR; Exact sciences and technology; Iron group (3d) ions and impurities (ti-cu); Magnetic resonances and relaxations in condensed matter, mössbauer effect; Optical spectra; Oxide glasses; Physics; Vanadyl ion; 61.40; DC conductivity; Chloroborate glasses; EPR; 66.30; Oxide glasses; 76.30; Optical spectra; Vanadyl ion; 72.20; Inorganic compounds; Electrical conductivity; Tetragonal lattices; ESR; Ternary systems; Doping; Composition effect; 72.20 EPR; Experimental study; Borate glasses; Spin Hamiltonians; Boron oxides; Absorption spectra; Halide glass; Activation energy
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/S0921-4526(03)00097-8

Electron paramagnetic resonance, optical transmission spectra and DC conductivity of the glasses 2 xMX·(0.30− x) M 2O ·0.70B 2O 3 ( M=Na or K; X=Cl or Br) (0.01⩽ x⩽0.10) containing 2.0 mol% of V 2O 5 have been studied. The spin-Hamiltonian parameters (SHP) of the VO 2+ ions, the dipolar hyperfine parameter, P, the Fermi contact interaction parameter, K, and the molecular orbital coefficients ( α 2 and γ 2) have been calculated. It is observed that in K X·K 2O ·B 2O 3 ( X=Cl or Br) glasses, the tetragonal nature of V 4+O 6 complex decreases with KBr for x⩾0.05. An increase in the 2K X:K 2O ratio ( x⩾0.05) also results in the contraction of 3dxy orbit of the unpaired electron in the vanadyl ion, whereas in case of Na X·Na 2O ·B 2O 3 ( X=Cl or Br) glasses, the SHP are independent of change in 2Na X: M 2O ratio. It is observed that the SHP in these alkali halide borate glasses are independent of the theoretical optical basicity, Λ th. It is also observed that the DC conductivity increases with increase in temperature. The order of conductivity is 10 −6 Ω −1 m −1 at low temperatures and 10 −4 Ω −1 m −1 at high temperatures. In MCl ·M 2O ·B 2O 3 ( M=Na or K) glasses, the conductivity increases and the activation energy decreases with an increase in mol% of the NaCl or KCl content whereas, in MBr ·M 2O ·B 2O 3 ( M=Na or K) glasses, the conductivity first increases and then decreases with mol% of the MBr content.