Near Constant Loss Dielectric Response in 2Bi2O3-B2O3 Glasses (original) (raw)
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Temperature dependent electrical transport characteristics of BaTiO3 modified lithium borate glasses
AIP Advances, 2015
The glass samples with composition (70B 2 O 3-29Li 2 O-1Dy 2 O 3)-xBT; x = 0, 10 and 20 weight percent, have been prepared by conventional melt quench technique. The dielectric measurements as a function of temperature have been carried out on these samples in the frequency range 1 Hz-10 MHz. The dielectric relaxation characteristics of these samples have been studied by analyzing dielectric spectroscopy, dielectric loss, electric modulus formulation and electrical conductivity spectroscopy. It is found that the dielectric permittivity of the samples increases with an increase in the temperature and BT content. The frequency dependent ac conductivity has been analyzed using Jonscher's universal power law whereas non exponential KWW function has been invoked to fit the experimental data of the imaginary part of the electric modulus. The values of the activation energy determined from the electric modulus and that from dc conductivity have been found to be quite close to each other suggesting that the same type of charge barriers are involved in the relaxation and the conduction mechanisms. The stretched exponent (β) and the power exponent (n) have been found to be temperature and composition dependent. The decrease in n with an increase in temperature further suggested that the ac conduction mechanism of the studied samples follows the correlated barrier hopping (CBH) model.
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
Electrical conduction and dielectric properties of Bi2O3–B2O3–TeO2 glass
Journal of Materials Science, 2014
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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
Electrical transport characteristics of ZnO–Bi2O3–B2O3 glasses
Ionics, 2012
Optically clear glasses in the ZnO-Bi 2 O 3-B 2 O 3 (ZBBO) system were fabricated via the conventional meltquenching technique. Dielectric constant and loss measurements carried out on ZBBO glasses unraveled nearly frequency (1 kHz-10 MHz)-independent dielectric characteristics associated with significantly low loss (D0 0.004). However, weak temperature response was found with temperature coefficient of dielectric constant 18 ± 4 ppm°C −1 in the 35-250°C temperature range. The conduction and relaxation phenomena were rationalized using universal AC conductivity power law and modulus formalism respectively. The activation energy for relaxation determined using imaginary parts of modulus peaks was 2.54 eV which was close to that of the DC conduction implying the involvement of similar energy barriers in both the processes. Stretched and power exponents were temperature dependent. The relaxation and conduction in these glasses were attributed to the hoping and migration of Bi 3+ cations in their own and different local environment.
Electrical characterization of lithium bismuth borate glasses containing cobalt/vanadium ions
Solid State Ionics, 2017
The present work reports the frequency, temperature and composition dependence of ac & dc conductivity, dielectric constant and impedance spectroscopic parameters for glass system having composition x (2CoO•V 2 O 5)•(30 − x)Li 2 O•20Bi 2 O 3 •50B 2 O 3 (x = 0.0, 2.0, 5.0, 7.0 and 10.0 mol%), 7CoO•23Li 2 O•20Bi 2 O 3 •50B 2 O 3 and 7V 2 O 5 •23Li 2 O•20Bi 2 O 3 •50B 2 O 3 synthesized through melt-quench route. The investigations are carried out overwide ranges of frequency (1 kHz-5 MHz) and temperature (100°C-400°C). The effects of mixed-transition metal ions (i.e. Co and/or V-ions) on ac conductivity and dielectric properties have been investigated using impedance spectroscopy. Jonscher power law (JPL) is observed to be followed by all synthesized glass compositions. A synergic change in values of all electric and dielectric parameters at 7.0 mol% confirms the structural modification due to mixed transition metal ion effect in present glass system. Electric modulus of prepared glass samples exhibits an asymmetric peak for the imaginary part (M″) reflecting a non-Debye type relaxation. The complex impedance curves (Z′ (ω) vs. Z″ (ω)) for all glass samples were plotted and found to exhibit good single well-shaped semi circles over the studied temperature range which depicts a single conduction mechanism. Dc conductivity at constant applied voltage (10 Volts) is also measured. Conductivity plots and electric modulus spectra were scaled according to the Summerfield Scaling Model. Both scaling behavior reflected the time temperature superposition principal and temperature independent conduction mechanism in the present glass system.
DSC and DC Conductivity of Bi2O3 · LiF · B2O3 Glasses
ISRN Ceramics, 2013
Fluoroborate glasses with Bi2O3 content and having compositions xBi2O3 · (40-x)LiF · 60B2O3 (x = 0, 5, 10, 15, and 20) are prepared using melt-quench technique. DSC characterization is carried out to observe glass transition temperature. Two such temperatures are observed for each of the reported samples. DC conductivity of the reported samples is studied with the variation in temperature from 313 K to 413 K by dividing this range into three regions, namely, low-, intermediate-, and high-temperature regions. DC conductivity responses for these temperature regions are explained using different conductivity models.
Effect of alkali content on AC conductivity of borate glasses containing two transition metals
Physica B-condensed Matter, 2009
Sodium borate glasses containing iron and molybdenum ions with the total concentration of transition ions constant and gradual substitution of sodium oxide (network modifier) by borate oxide (network former) was prepared. Densities, molar volume, DC and AC conductivities are measured. The trends of these properties are attributed to changes in the glass network structure. Their DC and AC conductivity increased with increasing NaO concentration. The increase of AC conductivity of sodium borate glasses is attributed to the chemical composition and the hopping mechanism of conduction. Measurements of the dielectric constant (ε) and dielectric loss (tan δ) as a function of frequency (50 Hz–100 kHz) and temperature (RT—600 K) indicate that the increase in dielectric constant and loss (ε and tan δ) values with increasing sodium ion content could be attributed to the assumption that Fe and Mo ions tend to assume network-forming position in the glass compositions studied.The variation of the value of frequency exponent s for all glass samples as the function of temperature at a definite frequency indicates that the value of s decreases with increasing the temperature which agrees with the correlated barrier-hopping (CBH) model.