Low loss and frequency (1 kHz1 MHz) independent dielectric characteristics of 3BaO3TiO2B2O3 glasses (original) (raw)
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Near Constant Loss Dielectric Response in 2Bi2O3-B2O3 Glasses
International Journal of Applied Glass Science, 2011
Electrical conduction and relaxation phenomena in bismuth borate glasses in the composition 2Bi 2 O 3-B 2 O 3 (Bi 4 B 2 O 9) were investigated. Dielectric studies carried out on these glasses revealed near constant loss (NCL) response in the 1 kHz to 1MHz frequency range at moderately high temperatures (300-450K) associated with relatively low loss (D=0.006) and high dielectric constant (ε r '=37) at 1kHz,300K. The variation in AC conductivity with temperature at different frequencies showed a cross over from NCL response characterized by local ion vibration within the potential well to universal Joncher's power law dependence triggered by ion hopping between potential wells or cages. Thermal activation energy for single potential well was found to be 0.48±0.05eV from cross over points. Ionic conduction and relaxation processes were rationalized by modulus formalism. The promising dielectric properties (relatively high ε r ' and low D) of the present glasses were attributed to high density (93 % of its crystalline counterpart), high polarizability and low mobility associated with heavy metal cations, Bi 3+ .
Journal of the European …, 2004
Vitrification and crystallization properties of glasses of the system BaO-TiO 2 -PbO-Al 2 O 3 (B 2 O 3 ) were investigated. The fields of vitrification based on ternary diagrams of BaTiO 3 -PbTiO 3 -(TiO 2 +Al 2 O 3 +B 2 O 3 ) with varied contents of Al 2 O 3 (10, 13, 16 mol.%) and B 2 O 3 (3, 15 mol.%) were identified. The glass compositions obtained had relatively low melting temperature (%1450 C). These stable glasses could be thermally treated to produce glass-ceramics characterized by fine-crystalline structures and regulated permittivity associated to the contents of ferroelectric phases. The phase composition of such glass-ceramics included different Pb x Ba 1-x TiO 3 solid solutions depending on the starting chemical composition. Permittivity of the obtained materials (f=800 kHz, T=25 C) varied from 20 to 680 relatively to the time of crystallization. #
Dielectric behaviour of glasses and glass ceramics in the system BaO-PbO-TiO2-B2O3-SiO2
Bulletin of Materials Science, 1987
Glasses wflh varying molar ratios of PbO/BaO in the system BaO-PbO-TiO z-B2Os-SiO 2 were prepared keeping (BaO + PbO)/TiO 2 ralio equal to one. The glasses were ccramized by lwo-slage heat treatment. X-ray diffraction indicales that PbTiO 3 crystallizes in lead-rich glasses while BaTiO 3 precipilates in barium-rich compositions. Solid solution (Ba, Pb)TiO s does not seem to crystallize over the entire range of compositions. Simultaneous presence of PbO and BaO in the initial glass composition reduces the yield of ferroelectric phase. Dielectric properties have been interpreted in terms of microstructural features.
Dielectric properties of Li2O3B2O3 glasses
Journal of Applied Physics, 2009
The frequency and temperature dependence of the dielectric constant and the electrical conductivity of the transparent glasses in the composition Li 2 O-3B 2 O 3 (LBO) were investigated in the 100 Hz-10 MHz frequency range. The dielectric constant and the loss in the low frequency regime were electrode material dependent. Dielectric and electrical relaxations were respectively analyzed using the Cole-Cole and electric modulus formalisms. The dielectric relaxation mechanism was discussed in the framework of electrode and charge carrier (hopping of the ions) related polarization using generalized
Dielectric Dispersion in PbO-Bi2O3-B2O3 Glasses Mixed with TiO2
Turkish Journal of …, 2008
[(PbO)0.20−x•(Bi2O3)0.40•(B2O3)0.40]:(TiO2)x, 0.0 ≤ x ≤ 0.02 glasses were prepared. Dielectric properties (dielectric constant ε , loss tan δ and a.c. conductivity σac, over a wide range of frequency and temperature), optical absorption, ESR and IR spectra of these glass materials have been investigated. The dielectric study has revealed that the glasses possess high insulating strength when TiO2 concentration is >0.8 mol% in the glass matrix. The optical absorption spectra of these glasses exhibited bands due to Ti 3+ ions in the visible region. ESR spectral studies have also indicated that a fraction of Ti 4+ ions reduced to Ti 3+ ions. IR spectra of these glasses exhibited bands due to TiO4 and TiO6 structural units. Quantitative studies indicate that as concentration of TiO2 is increased to 0.8 mol% in the glass matrix, a large proportion of titanium ions exist in Ti 3+ state and has influenced the physical properties of these glasses to a substantial extent.
Materials Today: Proceedings, 2019
Phosphate glasses of the ternary system Bi 2 O 3-Nb 2 O 5-P 2 O 5 were studied in two compositional series, namely xBi 2 O 3-5Nb 2 O 5-(95Àx)P 2 O 5 (serie B), with x = 10-17,5 mol% Bi 2 O 3 , and 10Bi 2 O 3 ÀxNb 2 O 5-(90Àx) P 2 O 5 (serie N), with x = 2,5-15 mol% Nb 2 O 5. Seven homogeneous glassy samples were prepared, and their amorphous structure were confirmed by X-ray diffraction. The dielectric properties such as dielectric constant (e 0) and dielectric loss (tand) were determined as a function of temperature ranging from 100°C to 500°C at a fixed applied frequency of 16 kHz. Replacing P 2 O 5 by Bi 2 O 3 or Nb 2 O 5 decreases the dielectric parameters in both series. These results are attributed to the increase in the cross-link density and the rigidity of the glass, leading therefore to a decrease of the polarization. The usual increasing behavior of (e 0) and (tand) with temperature may be explained by the augmentation of the orientation polarization and the electrical conduction losses values.
The dielectric behavior of a thermoelectric treated B 2 O 3 –Li 2 O–Nb 2 O 5 glass
A transparent glass with the composition 60B 2 O 3 –30Li 2 O–10Nb 2 O 5 (mol%) was prepared by the melt-quenching technique. Glass–ceramics, containing LiNbO 3 ferroelectric crystallites, were obtained by heat-treatment (HT) above 500 °C, with and without the presence of an external electric field. The dielec-tric properties of the glass and glass–ceramic were investigated, as a function of temperature (270– 315 K), in the 10 mHz–32 MHz frequency range. The presence of an external electric field, during the heating process, improves the formation of LiNbO 3 crystallites. The rise of the treatment temperature and the applied field, during the heat-treatment, leads to a decrease in the dc electric conductivity (r dc), indicating a decrease of the charge carriers number. The dielectric permittivity (e 0) values (300 K;1 kHz) are between 16.25 and 18.83, with the exception of the 550 °C HT sample that presents a e 0 value of 11.25. An electric equivalent circuit composed by an R in parallel with a CPE element was used to adjust the dielectric data. The results reflect the important role carried out by the heat-treatment and the electric field during the HT in the electric properties of glass–ceramics.
Microstructural and dielectric behaviour of glass ceramics in the system PbO-BaO-TiO2-B2O3-SiO2
Bulletin of Materials Science, 1986
Glasses in the system PbO-BaO-TiO2-BzO3-SiO2 with and without PzO5 as nucleant have been prepared. The glass samples were ceramized based on DTA studies. The ferroelectric phase crystallizing out has been found to be BaTiO3 from XRD. The optical and scanning electron micrographs show the presence of BaTiO3 as major phase. In these glass ceramic samples, dielectric constant and dissipation factor are approximately constant with temperature and frequency upto the glass transition temperature T~ and thereafter increase sharply with temperature and finally level off. The addition of P20~ as nucleant and molar ratio of (PbO + BaO) to TiO2 has marked influence on the dielectric behaviour and composition of ferroelcetric phase crystallizing out.
Glasses with composition 60B 2 O 3 -10TeO 2 -5TiO 2 -25R 2 O ( R= Li, Na & K) have been prepared using normal melt-quench technique. Dielectric measurements were carried out in the frequency range from 100Hz to 1MHz and in temperature range from room temperature (RT) to 350 o C by using alternating current impedance spectroscopy. The dielectric constant values increase with increase in temperature. Dielectric value lies in the range of 30-170 for lithium, 30-80 for sodium and 32-60 for potassium containing boro tellurite glasses. It is also found that dielectric constant values decrease with increasing frequency. The temperature dependence of the dielectric constant () shows that, at relatively lower temperature, the electric dipoles formed in the glasses are frozen and rotated at the softening temperature of the glass.. At elevated temperature the glassy network gets relaxed while, motion charge carrier and dipoles become easier. Each () and ()was found to be dependent on the alkali oxide. Dielectric constant values are found to be high for lithium containing glass
The effect of glass addition on the dielectric properties of barium strontium titanate
Abstract Ba0.7Sr0.3TiO3 (BST) ceramics were prepared by the conventional solid state ceramic route. Different weight percentages of twelve different glasses were added to the calcined BST ceramics and sintered. The structure and microstructure of the sintered materials were investigated by X-ray diffraction and Scanning Electron Microscopic techniques. The low frequency dielectric properties of the glass-ceramic composites were measured using LCR meter. Some of the glasses improved the dielectric properties and considerably lowered the sintering temperature. The glasses were prepared and characterized under identical conditions. Among the different glasses, 1.5 wt% addition of 71ZnO–29B2O3 lowered the sintering temperature of BST to 975 C with a dielectric loss of 9 · 10–3 and dielectric constant of 875 at 1 MHz. The curie temperature of BST ceramics was found to shift towards lower temperature with glass addition