共查询到20条相似文献,搜索用时 15 毫秒
1.
Koushik Majhi Kalidhindi B. R. Varma 《International Journal of Applied Ceramic Technology》2010,7(Z1):E89-E97
Glasses in the system CaO–Bi2O3–B2O3 (in molar ratio) have been prepared using melt-quenching route. Ion transport characteristics were investigated for this glass using electric modulus, ac conductivity and impedance measurements. The ac conductivity was rationalized using Almond–West power law. Dielectric relaxation has been analyzed based on the behavior of electric modulus behavior. The activation energy associated with the electrical relaxation determined from the electric modulus spectra was found to be 1.76 eV, close to that the activation energy for dc conductivity (1.71 eV) indicating that the same species took part in both the processes. The stretched exponent β (0.5–0.6) is invariant with temperature for the present glasses. 相似文献
2.
Nazrin S. N. Umar S. A. Halimah M. K. Marian M. M. Najwa Z. W. Jufa M. S. Syahirah M. T. Zuhasanah Z. Azlan M. N. Geidam I. G. Boukhris Imed Kebaili Imen 《Journal of Inorganic and Organometallic Polymers and Materials》2022,32(7):2513-2526
Journal of Inorganic and Organometallic Polymers and Materials - Copper oxide doped TeO2–B2O3 glass system with empirical formula;... 相似文献
3.
To support commercialization of the MgO–Al2O3–B2O–SiO2-based low-dielectric glass fibers, crystallization characteristics of the relevant glasses was investigated under various heat-treatment conditions. The study focused on the effects of iron on the related thermal properties and crystallization kinetics. Both air-cooled and nucleation-treated samples were characterized by using the differential thermal analysis/differential scanning calorimeter method between room temperature and 1200°C. A collected set of properties covers glass transition temperature (Tg), maximum crystallization temperature (Tp), specific heat (ΔCp), enthalpy of crystallization (ΔHcryst), and thermal stability (ΔT=Tp—Tg). Using the Kinssiger method, the activation energy of crystallization was determined. Crystalline phases in the samples having various thermal histories were determined using powder X-ray diffraction (XRD) and/or in situ high-temperature XRD method. Selective scanning electron microscope/energy-dispersive spectroscopy analysis provided evidence that crystal density in the glass is affected by the iron concentration. Glass network structures, for air-cooled and heat-treated samples, were examined using a midinfrared spectroscopic method. Combining all of the results from our study, iron in glass is believed to function as a nucleation agent enhancing crystal population density in the melt without altering a primary phase field. By comparing the XRD data of the glasses in two forms (bulk versus powder), the following conclusions can be reached. The low-dielectric glass melt in commercial operation should be resistant to crystallization above 1100°C. Microscopic amorphous phase separation, possibly a borate-enriched phase separating from the silicate-enriched continuous phase can occur only if the melt is held at temperatures below 1100°C, that is, below the glass immiscibility temperature. The study concludes that neither crystallization nor amorphous phase separation will be expected for drawing fibers between 1200°C and 1300°C in a commercial operation. 相似文献
4.
《Journal of the European Ceramic Society》2014,34(16):4383-4388
Homogeneous transparent optical glass–ceramics precipitated with unique nonlinear crystals are promising materials for photonic applications. We have utilized heat treatment method to prepare transparent ZnO–Bi2O3–B2O3 glass–ceramic containing Bi2ZnB2O7 nonlinear nanocrystals. A large third-order nonlinear susceptibility χ(3) of glass–ceramic is measured by Z-scan technique, which mainly attributed to unique [BiO6] and [B2O5] units in Bi2ZnB2O7 crystal structure and the quantum size effect of nanoparticles. The discovery is of great potential in the application of nonlinear optical integrated devices. 相似文献
5.
I. A. Sokolov I. V. Murin N. A. Mel'nikova A. A. Pronkin 《Glass Physics and Chemistry》2003,29(3):291-299
The steady-state electrical conductivity of oxychloride glasses in the PbCl2–PbO · B2O3 and PbCl2–2PbO · B2O3 systems is investigated. In the temperature range from 190 to 380°C, the dependence of log on the reciprocal of the temperature exhibits a linear behavior. The nature of charge carriers is studied using the Hittorf technique. It is demonstrated that protons and chlorine ions are charge carriers in solid glasses. The concentration dependence of the transport numbers of chlorine ions is examined by the Tubandt method. The contribution of the electronic component to the total electrical conductivity is estimated with the use of the Liang–Wagner technique. The concentration dependences of the electrical conductivity and the transport numbers of chlorine ions are interpreted in terms of the microinhomogeneous glass structure associated with the selective interaction of components during synthesis of glasses. 相似文献
6.
《Ceramics International》2017,43(14):11132-11141
Dy3+ doped calcium bismuth borate glasses were synthesized in the composition range of xLiCl-(30 − x)CaO-20Bi2O3-50B2O3 + 1 mol% Dy2O3 (x = 0, 2, 5, 7, 10 and 15 mol%, LC0, LC2, LC5, LC7, LC10 and LC15 respectively) using conventional melt-quench technique. Broad XRD profiles confirmed non-crystalline nature of synthesized compositions. The compositional dependencies of structural changes (using FTIR spectra), thermal behavior (using DSC thermographs) and optical band gap (using UV–Vis–NIR spectra) were discussed. Photoluminescence (PL) excitation spectra recorded at 577 nm yielded six different excitation peaks belonging to Dy3+ ions. The PL emission spectra recorded at 451 nm were analyzed to extract different light emission parameters viz. Y/B ratio, color coordinates, correlated color temperature (CCT) following CIE 1931 chromaticity diagram. The emission colors were found to lie in white light region and lies very close to standard white light emission. The CCT of sample LC10 (5335 K) is closest to CCT of standard white light (5615 K) which depicted the optimized concentration of LiCl for application of these glasses in WLED application. 相似文献
7.
《Journal of the European Ceramic Society》1999,19(1):139-142
Dielectric ceramics in the BaO–Nd2O3–TiO2–Ta2O5 system were prepared and characterized. The ceramics with tungsten–bronze structure based on the compositions Ba2NdTi2Ta3O15 and Ba5NdTi3Ta7O30 had a high dielectric constant (>100) with a lower frequency-dependency when complete densification was achieved; a low dielectric loss was obtained in the former. 相似文献
8.
AbstractVariation in the viscous flow behaviour, nature and extent of glass fluidity in glass/filler composites are addressed with respect to various factors such as filler type, content, size, density and migration distance. The characterisation of a glass (Bi2O3–B2O3–ZnO) composite consisting of two different fillers (cordierite and willemite) was determined using hot stage microscopy, a differential scanning calorimeter and a flow button test. The microstructure was analysed using a scanning electron microscope. The apparent viscosity of the glass composites increased on increasing concentration and density of the filler. The variation in the viscosity is due to the diffusion of the glass matrix through channels in the cordierite filler of the composite. Based on the calculated migration distance of the filler in the glass matrix, the present work suggests that the interfacial behaviour and the density of the filler play a significant role in determining the viscous flow of the glass composites. 相似文献
9.
Kecheng Li Hong Wang Huanfu Zhou Minghui Zhang Xi Yao 《International Journal of Applied Ceramic Technology》2010,7(Z1):E144-E150
The effects of Li2O–ZnO–B2O3 glass additive on the sintering behavior, phase formation, microstructure, and microwave dielectric properties of ZnTiNb2O8 ceramics have been investigated. The sintering temperature of ZnTiNb2O8 ceramics can be effectively reduced from 1200°C to 875°C by adding a small amount of Li2O–ZnO–B2O3 glass, while no obvious degradation of the microwave dielectric properties was induced. Typically, the 2.0 wt% Li2O–ZnO–B2O3 glass-added ceramic sintered at 875°C has better microwave dielectric properties of ɛr=31.8, Q×f=25,013 GHz, and τf=−62 ppm/°C. In addition, the ceramics can be co-fired well with an Ag electrode. 相似文献
10.
《Journal of the European Ceramic Society》2014,34(15):3729-3734
Liquidus line in the high-Bi2O3-containing region of the TiO2–Bi2O3 system was determined experimentally. The equilibrating and quenching technique with subsequent electron probe microanalyser (SEM-EDS) microanalysis were employed. Based on the data, liquidus line was constructed between 60 and 92 mol% Bi2O3. The current results showed a higher solubility of Bi2O3 in the liquid phase in equilibrium with the Bi4Ti3O12 compound compared with the existing phase diagram. In addition, differential scanning calorimetry (DSC) was used to estimate the transformations covering the composition range from 60 to 95 mol% Bi2O3. Further, the phase diagram of the TiO2–Bi2O3 system was calculated using a quasichemical model for the liquid phase. The thermodynamic properties of the intermediate compounds were estimated from the data of TiO2 and Bi2O3 pure solids. 相似文献
11.
Nb2O5 and Nb–Co doped 0.85BaTiO3–0.15Bi(Mg1/2Ti1/2)O3 (0.85BT–0.15BMT) ceramics were investigated. From XRD patterns, undesired phase was observed when the (Nb2O5/Nb-Co) doping levels exceed 3 wt.%/2 wt.%, giving rise to the deteriorate dielectric constant. The 0.85BT–0.15BMT ceramics doped with 2 wt.%Nb2O5 was found to possess a moderate dielectric constant (? ~ 1000) and low dielectric loss (tan δ = 0.9%) at room temperature and 1 kHz, showing flat dielectric behavior over the temperature range from ?55 to 155 °C. It was found that the formation of core–shell structure in the BT based ceramics is controlled by the doping sequence of Nb- and Bi-oxides. 相似文献
12.
Alzahrani Jamila S. Alrowaili Z. A. Saleh H. H. Al-Baradi Ateyyah M. Alothman Miysoon A. Al-Buriahi M. S. 《Journal of Inorganic and Organometallic Polymers and Materials》2021,31(11):4300-4312
Journal of Inorganic and Organometallic Polymers and Materials - This research article focuses on the significant role of Tb2O3 content on the optical properties and radiation shielding performance... 相似文献
13.
Sergey Sirotkin Robert Meszaros Lothar Wondraczek 《International Journal of Applied Glass Science》2012,3(1):44-52
We report on chemical stability and corrosion behavior of highly depolymerized sulfophosphate glasses from the system ZnO–Na2O–SO3–P2O5 in aqueous solution, providing data on weight loss, ion release rates, and modifications of surface topology as a function of time, temperature and pH value. Observations seem consistent with the previously developed structural model of chemical heterogeneity, where cations Na+ and Zn2+ cluster selectively in the vicinity of sulfate and phosphate anions, respectively. 相似文献
14.
V. V. Golubkov O. S. Dymshits A. A. Zhilin A. V. Redin M. P. Shepilov 《Glass Physics and Chemistry》2001,27(6):504-511
The changes in the structure and phase composition of glasses in the K2O–Nb2O5–SiO2system upon their heat treatment in the temperature range 700–800°C are studied by the small-angle X-ray scattering (SAXS) technique and X-ray powder diffraction. It is demonstrated that the crystallization is the primary process giving rise to microinhomogeneities in glasses due to heat treatment. Nanocrystals of an unidentified niobium-containing phase precipitate in glasses with the formation of regions with a decreased content of potassium and niobium oxides. An increase in the duration of heat treatment at the studied temperatures results in an increase in the size of nanocrystals without change in their phase composition. This is accompanied by the disappearance of diffusion zones, which leads to a decrease in the SAXS intensity in the range of small scattering angles and, correspondingly, to a decrease in the light scattering intensity. 相似文献
15.
16.
Effect of Tungsten Oxide on the Crystallization Properties of Glasses of the B2O3–La2O3–Nb2O5 System
Glass Physics and Chemistry - The effect of tungsten oxide on the crystallization properties of glasses of the 37.5B2O3 22.5La2O3 (40 – x)Nb2O5 xWO3 (where x = 10, 15, 20, 30, 40 mol %)... 相似文献
17.
《Ceramics International》2020,46(5):5575-5585
50Bi2O3–35B2O3–15ZnO (mol. %) glass referred to as Bi50 glass, was used to braze Al2O3 ceramics. The phase transformations and wettability of the Bi50 glass on Al2O3 substrates at different temperatures were investigated. The results showed that the chemical compatibility of Bi50 glass and Al2O3 substrates at 650 °C was excellent. However, Al2O3/Al2O3 joints having a considerable volume fraction of pores and unbonding were obtained when the joining procedures were carried out by a one-step brazing method. Based on the experiments and simulation results, the prime determinants responsible for the presence of the pores and unbonding within the brazing joints can be divided into two aspects: (i) the intrinsic causes leading to the formation of closed pores (ii) the external factors causing the failure of pores and glass separation. Ultimately, an advanced joining procedure named two-step brazing was proposed, and joints nearly free of defects were acquired. 相似文献
18.
19.
I. A. Sokolov I. V. Murin N. A. Mel'nikova A. A. Pronkin 《Glass Physics and Chemistry》2002,28(4):239-245
The temperature–concentration dependences of the electrical conductivity and the activation energy for electrical conduction of glasses in the Na2O–B2O3 and Na2O–2PbO · B2O3 systems are studied. The investigation into the nature of the electrical conduction in these glasses reveals that the contribution from the electronic component (10–3%) of the conductivity is within the sensitivity of the Liang–Wagner technique. A considerable alkali conductivity is observed upon introduction of more than 12 mol % Na2O. The true transport number of sodium Na is as large as unity at [Na2O] 15 mol %. It is shown that the observed temperature–concentration dependences of the electrical and transport properties are governed by the ratio between the concentrations of polar and nonpolar structural–chemical units of the Na+[BO4/2]–, Na+[O–BO2/2] Na+[O–BO2/2], Pb2+
1/2[BO4/2]–, Pb2+
1/2[O–BO2/2], and [BO3/2] types. 相似文献
20.
Al-Buriahi M. S. Kavaz E. Perişanoğlu U. Alalawi A. Çakıcı T. Alomairy S. Rammah Y. S. 《Journal of Inorganic and Organometallic Polymers and Materials》2021,31(12):4546-4562
Journal of Inorganic and Organometallic Polymers and Materials - In the current study, 10PbO-xSrO-(90-x)B2O3 (x is between 20 and 45 mol% with a step of 5 mol%) glasses with SrO... 相似文献