2003 1 Effect of Bi2O3 on EPR, optical transmission and DC conductivity of vanadyl doped alkali bismuth borate glasses Agarwal 2003 (original) (raw)
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Journal of Physics and Chemistry of Solids, 2003
Glasses with composition x Bi 2 O 3 ·(30 2 x)M 2 O·70B 2 O 3 (M ¼ Li, Na) containing 2 mol% V 2 O 5 have been prepared over the range 0 # x # 15 (x is in mol%). The electron paramagnetic resonance spectra of VO 2þ of these glasses have been recorded in the X-band (<9.3 GHz) at room temperature (RT < 300 K). Spin Hamiltonian parameters, g k ; g ' ; A k ; A ' ; dipolar hyperfine coupling parameter, P; and Fermi contact interaction parameter, K; have been calculated. The molecular orbital coefficients, a 2 and g 2 ; have been calculated by recording the optical transmission spectra. In x Bi 2 O 3 ·(30 2 x)Li 2 O·70B 2 O 3 glasses there is decrease in the tetragonality of the V 4þ O 6 complex for x up to 6 mol% whereas for x $ 6 mol%, tetragonality increases. In x Bi 2 O 3 ·(30 2 x)Na 2 O·70B 2 O 3 glasses there is increase in the tetragonality of the V 4þ O 6 complex with increasing x: The 3d xy orbit expands with increase in Bi 2 O 3 :M 2 O ratio. Values of the theoretical optical basicity, L th ; have also been reported. The DC conductivity increases with increase in temperature. The order of conductivity is 10 25 ohm 21 m 21 at low temperature and 10 23 ohm 21 m 21 at high temperature. The DC conductivity decreases and the activation energy increases with increase in Bi 2 O 3 :M 2 O ratio. q
Glasses with composition x Bi 2 O 3 ·(30 2 x)M 2 O·70B 2 O 3 (M ¼ Li, Na) containing 2 mol% V 2 O 5 have been prepared over the range 0 # x # 15 (x is in mol%). The electron paramagnetic resonance spectra of VO 2þ of these glasses have been recorded in the X-band (<9.3 GHz) at room temperature (RT < 300 K). Spin Hamiltonian parameters, g k ; g ' ; A k ; A ' ; dipolar hyperfine coupling parameter, P; and Fermi contact interaction parameter, K; have been calculated. The molecular orbital coefficients, a 2 and g 2 ; have been calculated by recording the optical transmission spectra. In x Bi 2 O 3 ·(30 2 x)Li 2 O·70B 2 O 3 glasses there is decrease in the tetragonality of the V 4þ O 6 complex for x up to 6 mol% whereas for x $ 6 mol%, tetragonality increases. In x Bi 2 O 3 ·(30 2 x)Na 2 O·70B 2 O 3 glasses there is increase in the tetragonality of the V 4þ O 6 complex with increasing x: The 3d xy orbit expands with increase in Bi 2 O 3 :M 2 O ratio. Values of the theoretical optical basicity, L th ; have also been reported. The DC conductivity increases with increase in temperature. The order of conductivity is 10 25 ohm 21 m 21 at low temperature and 10 23 ohm 21 m 21 at high temperature. The DC conductivity decreases and the activation energy increases with increase in Bi 2 O 3 :M 2 O ratio. q
Glasses with composition xBi 2 O 3 ·(30 − x)K 2 O·70B 2 O 3 doped with 2 mol% of V 2 O 5 have been prepared over the range 0 ≤ x ≤ 15 (in mol%). The electron paramagnetic resonance spectra of VO 2+ in these glasses have been recorded in the X-band (≈9.3 GHz) at room temperature. The spin Hamiltonian parameters, dipolar hyperfine coupling parameter and Fermi contact interaction parameter have been calculated. It is observed that, with increase in Bi 2 O 3 :K 2 O ratio, tetragonal distortion of the V 4+ O 6 complex increases and there is an expansion of the 3d xy orbit of unpaired electron in the vanadium ion. The values of theoretical optical basicity have also been reported. The molecular orbital coefficients have been calculated by recording the optical transmission spectra in the wavelength range 500-850 nm. The direct-current electrical conductivity, σ, has been measured in the temperature range 443-523 K. σ decreases with increase in Bi 2 O 3 :K 2 O ratio because of the decrease in the mobility and number of mobile K + ions and there is no electronic contribution to the conductivity by Bi 2 O 3 .
Materials Chemistry and Physics, 2004
Glasses with composition xBi 2 O 3 ·(30 − x)K 2 O·70B 2 O 3 doped with 2 mol% of V 2 O 5 have been prepared over the range 0 ≤ x ≤ 15 (in mol%). The electron paramagnetic resonance spectra of VO 2+ in these glasses have been recorded in the X-band (≈9.3 GHz) at room temperature. The spin Hamiltonian parameters, dipolar hyperfine coupling parameter and Fermi contact interaction parameter have been calculated. It is observed that, with increase in Bi 2 O 3 :K 2 O ratio, tetragonal distortion of the V 4+ O 6 complex increases and there is an expansion of the 3d xy orbit of unpaired electron in the vanadium ion. The values of theoretical optical basicity have also been reported. The molecular orbital coefficients have been calculated by recording the optical transmission spectra in the wavelength range 500-850 nm. The direct-current electrical conductivity, σ, has been measured in the temperature range 443-523 K. σ decreases with increase in Bi 2 O 3 :K 2 O ratio because of the decrease in the mobility and number of mobile K + ions and there is no electronic contribution to the conductivity by Bi 2 O 3 .
Glasses with composition xBi 2 O 3 ·(70 −x)B 2 O 3 ·30Li 2 O containing 2 mol% V 2 O 5 have been prepared over the range 0 ≤ x ≤ 20 (in mol%). The electron paramagnetic resonance (EPR) spectra of VO 2+ ions of these glasses have been recorded in the X-band (≈9.13 GHz) at room temperature. Spin Hamiltonian parameters (SHP), g || , g ⊥ , A || , A ⊥ , dipolar hyperfine coupling parameter, P, and Fermi contact interaction parameter, K, have been calculated. The molecular orbital coefficients, α 2 and γ 2 , have been calculated by recording the optical transmission spectra in the wavelength range of 500-850 nm. It has been observed that the octahedral symmetry around V 4+ ion is improved, and the 3d xy orbit of the unpaired electron of the vanadium ion expands with increase in Bi 2 O 3 :B 2 O 3 ratio. Values of the theoretical optical basicity, Λ th , have also been reported. The dc conductivity increases with an increase in temperature. The dc conductivity variation with Bi 2 O 3 content shows mixed glass-former effect at x = 8 mol%. For x = 10 mol%, the conductivity decreases with increase in Bi 2 O 3 content because of the decrease in the mobility and the number of Li + ions available for the conduction. (A. Agarwal).
Glasses with composition xBi 2 O 3 ·(30 − x)K 2 O·70B 2 O 3 doped with 2 mol% of V 2 O 5 have been prepared over the range 0 ≤ x ≤ 15 (in mol%). The electron paramagnetic resonance spectra of VO 2+ in these glasses have been recorded in the X-band (≈9.3 GHz) at room temperature. The spin Hamiltonian parameters, dipolar hyperfine coupling parameter and Fermi contact interaction parameter have been calculated. It is observed that, with increase in Bi 2 O 3 :K 2 O ratio, tetragonal distortion of the V 4+ O 6 complex increases and there is an expansion of the 3d xy orbit of unpaired electron in the vanadium ion. The values of theoretical optical basicity have also been reported. The molecular orbital coefficients have been calculated by recording the optical transmission spectra in the wavelength range 500-850 nm. The direct-current electrical conductivity, σ, has been measured in the temperature range 443-523 K. σ decreases with increase in Bi 2 O 3 :K 2 O ratio because of the decrease in the mobility and number of mobile K + ions and there is no electronic contribution to the conductivity by Bi 2 O 3 .
Journal of Alloys and Compounds, 2004
Glasses with composition xBi 2 O 3 ·(70 −x)B 2 O 3 ·30Li 2 O containing 2 mol% V 2 O 5 have been prepared over the range 0 ≤ x ≤ 20 (in mol%). The electron paramagnetic resonance (EPR) spectra of VO 2+ ions of these glasses have been recorded in the X-band (≈9.13 GHz) at room temperature. Spin Hamiltonian parameters (SHP), g || , g ⊥ , A || , A ⊥ , dipolar hyperfine coupling parameter, P, and Fermi contact interaction parameter, K, have been calculated. The molecular orbital coefficients, α 2 and γ 2 , have been calculated by recording the optical transmission spectra in the wavelength range of 500-850 nm. It has been observed that the octahedral symmetry around V 4+ ion is improved, and the 3d xy orbit of the unpaired electron of the vanadium ion expands with increase in Bi 2 O 3 :B 2 O 3 ratio. Values of the theoretical optical basicity, Λ th , have also been reported. The dc conductivity increases with an increase in temperature. The dc conductivity variation with Bi 2 O 3 content shows mixed glass-former effect at x = 8 mol%. For x = 10 mol%, the conductivity decreases with increase in Bi 2 O 3 content because of the decrease in the mobility and the number of Li + ions available for the conduction. (A. Agarwal).
Glasses with composition xBi 2 O 3 ·(70 −x)B 2 O 3 ·30Li 2 O containing 2 mol% V 2 O 5 have been prepared over the range 0 ≤ x ≤ 20 (in mol%). The electron paramagnetic resonance (EPR) spectra of VO 2+ ions of these glasses have been recorded in the X-band (≈9.13 GHz) at room temperature. Spin Hamiltonian parameters (SHP), g || , g ⊥ , A || , A ⊥ , dipolar hyperfine coupling parameter, P, and Fermi contact interaction parameter, K, have been calculated. The molecular orbital coefficients, α 2 and γ 2 , have been calculated by recording the optical transmission spectra in the wavelength range of 500-850 nm. It has been observed that the octahedral symmetry around V 4+ ion is improved, and the 3d xy orbit of the unpaired electron of the vanadium ion expands with increase in Bi 2 O 3 :B 2 O 3 ratio. Values of the theoretical optical basicity, Λ th , have also been reported. The dc conductivity increases with an increase in temperature. The dc conductivity variation with Bi 2 O 3 content shows mixed glass-former effect at x = 8 mol%. For x = 10 mol%, the conductivity decreases with increase in Bi 2 O 3 content because of the decrease in the mobility and the number of Li + ions available for the conduction. (A. Agarwal).
Electron paramagnetic resonance, optical transmission spectra and DC conductivity of the glasses 2xMX Á (0.30Àx)M 2 O Á 0.70B 2 O 3 (M=Na or K; X=Cl or Br) (0:01pxp0:10) containing 2.0 mol% of V 2 O 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 (a 2 and g 2 ) have been calculated. It is observed that in KX Á K 2 O Á B 2 O 3 (X=Cl or Br) glasses, the tetragonal nature of V 4+ O 6 complex decreases with KBr for xX0:05: An increase in the 2KX:K 2 O ratio (xX0:05) also results in the contraction of 3dxy orbit of the unpaired electron in the vanadyl ion, whereas in case of NaX Á Na 2 O Á B 2 O 3 (X=Cl or Br) glasses, the SHP are independent of change in 2NaX:M 2 O ratio. It is observed that the SHP in these alkali halide borate glasses are independent of the theoretical optical basicity, L th : It is also observed that the DC conductivity increases with increase in temperature. The order of conductivity is 10 À6 O À1 m À1 at low temperatures and 10 À4 O À1 m À1 at high temperatures. In MCl Á M 2 O Á B 2 O 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 Á M 2 O Á B 2 O 3 (M=Na or K) glasses, the conductivity first increases and then decreases with mol% of the MBr content. r
Electron paramagnetic resonance, optical transmission spectra and DC conductivity of the glasses 2xMX Á (0.30Àx)M 2 O Á 0.70B 2 O 3 (M=Na or K; X=Cl or Br) (0:01pxp0:10) containing 2.0 mol% of V 2 O 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 (a 2 and g 2 ) have been calculated. It is observed that in KX Á K 2 O Á B 2 O 3 (X=Cl or Br) glasses, the tetragonal nature of V 4+ O 6 complex decreases with KBr for xX0:05: An increase in the 2KX:K 2 O ratio (xX0:05) also results in the contraction of 3dxy orbit of the unpaired electron in the vanadyl ion, whereas in case of NaX Á Na 2 O Á B 2 O 3 (X=Cl or Br) glasses, the SHP are independent of change in 2NaX:M 2 O ratio. It is observed that the SHP in these alkali halide borate glasses are independent of the theoretical optical basicity, L th : It is also observed that the DC conductivity increases with increase in temperature. The order of conductivity is 10 À6 O À1 m À1 at low temperatures and 10 À4 O À1 m À1 at high temperatures. In MCl Á M 2 O Á B 2 O 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 Á M 2 O Á B 2 O 3 (M=Na or K) glasses, the conductivity first increases and then decreases with mol% of the MBr content. r