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1.
FTIR spectroscopy has been employed to investigate the structure of CaF2–B2O3 glasses. It is proposed that CaF2 partially modifies the borate network forming
\textCa 1 / 2 2+ [\textBO 3 / 2 \textF] - {\text{Ca}}_{ 1 / 2}^{ 2+ } [{\text{BO}}_{ 3 / 2} {\text{F]}}^{ - } units. The rest of CaF2 is assumed to build an amorphous network formed of CaF4 tetrahedra. Analysis of density and molar volume revealed that the volume of CaF4 tetrahedron in the studied glasses is slightly greater than that in the crystalline form. Data of density, molar volume,
and electric conductivity have been correlated with the glass structure. As far as the authors know, CaF2–B2O3 glasses are investigated for the first time. 相似文献
2.
Wookyung Sung Jinho Kim Seongjin Hwang Hyungsun Kim 《Journal of Materials Science》2008,43(12):4016-4021
The properties of the composite, having a complicated microstructure, are decided by many factors such as those of glass matrix,
crystal phases, fillers, and holes. We investigated how the addition of ceramic fillers to the glass matrix affects the mechanical
and etching properties of the glass composite by forming new crystal phases. Different amounts of two fillers, ZnO and Al2O3, were added to a glass frit consisting of Bi2O3–ZnO–B2O3. It was sintered at 550 °C for 30 min. Based on the results of this study, the porosity and degree of crystallization of
the composites could be controlled by adjusting the content of the ZnO and Al2O3 fillers. Therefore, porosity and degree of crystallization formed by the reaction between a glass matrix and fillers influence
the mechanical and etching properties of the composite. 相似文献
3.
Gadolinium doped bismuth borate glasses containing up to 30 mol% Y2O3 were prepared by fast melt quenching method. The effect of yttrium on the local order in 3B2O3 · Bi2O3 and B2O3 · Bi2O3 glass matrices, particularly on the bismuth sites, was investigated by infrared (IR) spectroscopy and electron paramagnetic
resonance (EPR) of Gd3+ ions. The IR results show that the local structure is more ordered in the glass system with higher bismuth content and the
progressive addition of yttrium increases the local disorder in both bismuth–borate glass matrices. The EPR results indicate
that Gd3+ ions occupy both bismuth and yttrium sites and reflect the same structural disorder like that suggested by IR results. 相似文献
4.
Shaaban M. Salem E. M. Antar A. G. Mostafa S. M. Salem S. A. El-badry 《Journal of Materials Science》2011,46(5):1295-1304
(10Li2O–20GeO2–30ZnO–(40-x)Bi2O3–xFe2O3 where x = 0.0, 3, 6, and 9 mol%) glasses were prepared. A number of studies, viz. density, differential thermal analysis, FT-IR spectra,
DC and AC conductivities, and dielectric properties (constant ε′, loss tan δ, AC conductivity, σ
ac, over a wide range of frequency and temperature) of these glasses were carried out as a function of iron ion concentration.
The analysis of the results indicate that, the density and molar volume decrease with an increasing of iron content indicates
structural changes of the glass matrix. The glass transition temperature T
g and onset of crystallization temperature T
x increase with the variation of concentration of Fe2O3 referred to the growth in the network connectivity in this concentration range, while glass-forming ability parameter ΔT decrease with increase Fe2O3 content, indicates an increasing concentration of iron ions that take part in the network-modifying positions. The FT-IR
spectra evidenced that the main structural units are BiO3, BiO6, ZnO4, GeO4, and GeO6. The structural changes observed by varying the Fe2O3 content in these glasses and evidenced by FTIR investigation suggest that the iron ions play a network modifier role in these
glasses while Bi2O3, GeO2, and ZnO play the role of network formers. The temperature dependence of DC and AC conductivities at different frequencies
was analyzed using Mott’s small polaron hopping model and, the high temperature activation energies have been estimated and
discussed. The dielectric constant and dielectric loss increased with increase in temperature and Fe2O3 content. 相似文献
5.
Song Chen Shuren Zhang Xiaohua Zhou Bo Li 《Journal of Materials Science: Materials in Electronics》2011,22(3):238-243
The low-temperature co-fired ceramic (LTCC) composites containing quartz based on the eutectic system BaO–Al2O3–SiO2–B2O3 are fabricated at the sintering temperature below 980 °C. Preparation process and sintering mechanism were described and
discussed, respectively. The results indicated that the addition of quartz to the eutectic system can availably improve dielectric
properties of the LTCC composites. In addition, The LTCC composites with optimum compositions, which were obtained by the
regulation of an Al2O3 content in the composite, can express excellent dielectric properties (permittivity: 5.94, 5.48; loss: 7 × 10−4, 5 × 10−4), considerable CTE values (11.7 ppm. °C−1, 10.6 ppm. °C−1) and good mechanical properties (128 MPa,133 MPa). 相似文献
6.
S. M. Abo-Naf R. L. Elwan M. A. Marzouk 《Journal of Materials Science: Materials in Electronics》2012,23(5):1022-1030
SiO2–PbO–Bi2O3 glasses having the composition of 35SiO2–xPbO–(65−x)Bi2O3 (where x = 5, 10, 15, 20, 25, 35, 45; in mol%) have been prepared using the conventional melting and annealing method. Density, molar
volume and Vickers microhardness of the prepared glasses were measured. Infrared (IR) and UV–visible spectroscopic techniques
were used for structural studies of these glasses. Density as well as the microhardness increase systematically and, conversely,
the molar volume decreases with increasing the lead oxide content. This behavior can be explained by the correlation with
the glass structure. Increasing the lead oxide content (≥20 mol%) increases the network former PbO4 groups which can play an important role in increasing the connectivity and compactness of the glass matrix via increasing
the cross-linking with the other constituent silicate and bismuthate structural units. The increased compactness may explain,
in turn, the increase of the density and microhardness. IR spectra reinforce the idea that bismuth participates in the glassy
network predominantly as BiO6 octahedral structural units. UV–VIS optical absorption spectra revealed UV-charge transfer absorption bands related to the
contribution of Pb2+ ions in the region 350–385 nm; in addition to the extrinsic absorption of trace iron impurities in the range 220–290 nm.
In the visible region, three optical bands in the ranges 415–435, 605–650 and 880–890 nm were correlated with the contribution
of electronic transitions in Bi3+ ions. Calculation of the optical mobility gap and the width of the energy tail of glass from the UV–VIS absorption indicated
a slight increase followed by a decrease in their values. The behavior change occurred at the glass in which PbO content is
20 mol% where lead oxide starts to participate into the glassy matrix as a network former. The combination of analytical FTIR
and UV–visible spectroscopy provided a consistent picture of structure–property relations in this glass system. 相似文献
7.
L. T. Denisova L. A. Irtyugo Yu. F. Kargin L. G. Chumilina N. V. Belousova V. M. Denisov N. A. Galiakhmetova 《Inorganic Materials》2017,53(3):300-306
The compounds BiVO4, Bi4V2O11, and Bi12V2O23 have been prepared by solid-state synthesis using stoichiometric mixtures of Bi2O3 and V2O5. The effect of temperature on the heat capacity of the synthesized bismuth vanadates has been studied by differential scanning calorimetry in the range 350–950 K. The C p (T) curves have extrema at 531.7 K for BiVO4 and at 725.2 and 852.8 K for Bi4V2O11, which are due to polymorphic transformations of these compounds. 相似文献
8.
He Ming Zhang Shu Ren Zhou Xiao Hua 《Journal of Materials Science: Materials in Electronics》2011,22(4):389-393
The dielectric, thermal and mechanical properties of CaO–SiO2–B2O3 ternary system ceramics by solid-phase method have been carried out and quantitive analysis been examined by X-ray diffraction
(XRD) patterns. The results showed that the major crystalline phase of CaO–SiO2–B2O3 ternary system ceramics was wollastonite (about 90 wt%) which existed at the temperature ranging from 950 to 1,100 °C. It
is also observed that wollastonite could be transformed to pseudowollastonite at 1,200 °C. In addition, with increase in calcination
temperature, the amount of wollastonite increases. When the sintering temperature is at 1,100 °C, the amount of wollastonite
has a maximum value of 92.7 wt%. Accordingly, CaO–SiO2–B2O3 ternary system ceramics achieved excellent properties at 1,100 °C, such as dielectric constant of 8.38, dielectric loss of
1.51 × 10−3 at 1 MHz, linear thermal-expansion coefficient (300 K) of 6.68 × 10−6/K, bending strength of 121.75 Mpa. Analysis of the mechanical and dielectric properties showed that the measured bending
strength, dielectric constant and loss of CaO–SiO2–B2O3 ternary system ceramics can be substantially modified and improved by controlling the sintering temperature, in particular
due to the amount of wollastonite crystalline phase and size of grains. 相似文献
9.
Bin Li Wenqin Luo Yongya Wang Yanhui Zhang Haiyan Wu 《Journal of Materials Science》2018,53(11):8030-8038
The glass and glass ceramics containing SiO2–CaO–Fe2O3–P2O5 were prepared by sol–gel method. The influence of the Fe contents on the crystallization and local structure of the glass and glass ceramics was systematically investigated. The crystal structure of the glass ceramics was identified by XRD characterization. Hematite phase can be precipitated from the glass matrix in all glass ceramics with various Fe contents, and the crystallographic parameters of hematite were determined by XRD Rietveld refinement. The crystallization kinetics of the glasses was investigated in detail. Relative low activation energies were obtained at low Fe contents. The local structure evolution of the glass and glass ceramics has been studied in-depth by means of FTIR and Mössbauer spectroscopy. Fe element is present both as network former and network modifier which significantly influenced the crystallization activation energies of the glasses. The results of this work may be of great significance for the material design and practical applications of bioactive magnetic glass ceramics for hyperthermia. 相似文献
10.
Abdeslam Chagraoui Imane Yakine Abdelmjid Tairi Abdenajib Moussaoui Mohamed Talbi Mohamed Naji 《Journal of Materials Science》2011,46(16):5439-5446
A glass-forming domain is found and studied within Bi2O3–Sb2O3–TeO2 system. The glasses composition were obtained in pseudo-binary xSbO1.5, (1−x)TeO2 for 0.05 ≤ x ≤ 0.20. The constitution of glasses in the system Sb2O3–TeO2 was investigated by DSC, Raman, and Infrared spectroscopy. The influence of a gradual addition of the modifier oxides on
the coordination geometry of tellurium atoms has been elucidated based Infrared and Raman studies and showed the transition
of TeO4, TeO3+1, and TeO3 units with increasing Sb2O3 content. XRD results reveal the presence of three crystalline: γ-TeO2, α-TeO2, and SbTe3O8 phases during the crystallization process. The density of glasses has been measured. The investigation in the ternary system
by the solid state reaction using XRD reveals the existence of a solid solution Bi1−x
Sb1−x
Te2x
O4 isotopic to BiSbO4 with 0 ≤ x ≤ 0.1. 相似文献
11.
T. Jardiel A. C. Caballero L. Fuentes M. Villegas 《Journal of Materials Science》2009,44(21):5824-5828
In a recent report, the evaluation of the phase relations in the Bi2O3–TiO2–WO3 ternary system has shown the existence of a new phase with nominal composition close to Bi6Ti5WO22. In the present contribution we attempt to prepare this single phase by using a solid state route. Although XRD analyses
also show traces of two minority Aurivillius-type phases in the synthesized materials, the crystal structure of the Bi6Ti5WO22 phase has been determined by Rietveld analyses revealing a complex structure similar to that of Bi3(AlSb2)O11 and PbHoAl3O8 related compounds. The electrical response of this new phase was characterized as well. Three peaks are observed in its dielectric
response: two of them positioned around 0 °C and can be assigned to this Bi6Ti5WO22 structure. The third one rises up to 665 °C and confirms the presence of the Aurivillius-type phases. 相似文献
12.
In view of the potential engineering applications requiring machinability and wear resistance, the present work focuses to
evaluate hardness property and to understand the damage behavior of some selected glass–ceramics having different crystal
morphologies with SiO2–MgO–Al2O3–K2O–B2O3–F composition, using static micro-indentation tests as well as dynamic scratch tests, respectively. Vickers hardness of up
to 5.5 GPa has been measured in glass–ceramics containing plate like mica crystals. Scratch tests at a high load of 50 N in
artificial saliva were carried out in order to simulate the crack–microstructure interaction during real-time abrasion wear
and machining operation. The experimental observations indicate that the novel “spherulitic-dendritic” shaped crystals, similar
to the plate like crystals, have the potential to hinder the scratching induced crack propagation. In particular, such potential
of the ‘spherulitic-dendritic’ crystals become more effective due to the larger interfacial area with the glass matrix as
well as the dendritic structure of each mica plate, which helps in crack deflection and crack blunting, to a larger extent.
While modest damage tolerant behavior is observed in case of ‘spherulitic-dendritic’ crystal containing material, severe brittle
fracture of plate like crystals were noted, when both were scratched at 50 N load. 相似文献
13.
N. A. Gribchenkova K. G. Smorchkov A. G. Kolmakov A. S. Alikhanyan 《Inorganic Materials》2017,53(5):514-518
The pseudobinary system Al2O3–MgO has been studied in the temperature range 1750–2100 K by the Knudsen effusion method in combination with mass spectrometric analysis of the vapor phase. Over the entire composition range, except for the 100 mol % Al2O3 boundary, the vapor phase over the system consists of three species: Mg, O2, and O. The partial pressures obtained have been used to construct a p–x section through the Al2O3–MgO phase diagram at 1900 K. The standard enthalpy of formation of the MgAl2O4 spinel at 298 K has been determined by third-law calculations:–2301.61 ± 11.00 kJ/mol. We have derived equations for the temperature dependences of the partial pressures of the vapor species over the Al2O3–MgO system. 相似文献
14.
Differential thermal analysis and x-ray diffraction data indicate that the ZnO B2O3-CuO B2O3 join of the ternary system CuO-B2O3-ZnO is pseudobinary, with eutectic phase relations and a liquid-liquid miscibility gap in the composition range 25–35 mol % CuO.Translated from Neorganicheskie Materialy, Vol. 41, No. 3, 2005, pp. 339–340.Original Russian Text Copyright © 2005 by Kasumova, Bananyarly.This revised version was published online in April 2005 with a corrected cover date.This revised version was published online in April 2005 with a corrected cover date. 相似文献
15.
G. R. Gurbanov 《Inorganic Materials》2017,53(7):675-681
The Hall coefficient, resistivity, and thermoelectric power of quaternary tetradymite-like layered materials in the pseudoternary system Sb2Te3–GeTe–Bi2Te3 have been measured in the temperature range 100–800 K. The results demonstrate that all of the samples studied in the Sb2Te3–GeTe–Bi2Te3 system are p-type and have high hole concentration due to point defects. Plots of lnσ against 1/T in the intrinsic region were used to evaluate the band gap (ΔE) of two materials: GeSb3.91Bi0.03Te6.91(ΔE = 0.22 eV) and GeSbBiTe4 (ΔE = 0.197 eV). 相似文献
16.
Ioan Ardelean Simona Cora 《Journal of Materials Science: Materials in Electronics》2008,19(6):584-588
FT-IR, Raman and UV–VIS experimental results were presented for xCuO·(100-x)[3Bi2O3·B2O3] glass system, where 0 ≤ x ≤ 50 mol%. The FT-IR measurements indicate the presence in xCuO·(100-x)[3Bi2O3·B2O3] glasses of BO3, BO4 units, BiO3 pyramidal and distorted BiO6 octahedral units and their dependence of CuO content. The Raman scattering data indicate that for 0 ≤ x ≤ 10 mol% the structure of studied glasses consist from BiO3 pyramidal and distorted BiO6 octahedral units, ring and chain type of metaborate groups, ortoborate and pyroborate groups. For higher concentration the
Raman spectra suggest that the structure become more disordered. The FT-IR and Raman bands characteristic for CuO were not
directly evidenced, but the absorption bands specific for the glass matrix are influenced by the presence of copper ions in
the glass network structure. The optical absorption confirms the presence of Cu2+ in the CuO doped 3Bi2O3·B2O3 glass matrix. 相似文献
17.
This paper presents a detailed study of phase formation processes in the AgNO3–Sb2O3–MoO3 system during heating in air. The compositions of the solid-state reaction products have been determined using thermogravimetry and qualitative X-ray diffraction. The results demonstrate that, at a final heat treatment temperature of 1023 K, synthesis yields a range of Ag2–xSb2–xMo x O6 compounds with the pyrochlore structure and 0.0 ≤ x ≤ 2.0. The structural parameters of the synthesized phases have been refined by the Rietveld method in space group Fd3?m and their electrical conductivity has been measured. 相似文献
18.
Herein, we report the results of the in vitro dissolution tests, which were carried out by immersing the selected glass-ceramic samples in artificial saliva (AS) for various time periods of up to 42 days. In our experiments, the SiO(2)-MgO-Al(2)O(3)-K(2)O-B(2)O(3)-F glass ceramics with different crystal morphology and crystal content were used and a comparison is also made with the baseline glass samples (without any crystals). The bioactivity of the samples was probed by measuring the changes in pH, ionic conductivity and ionic concentration of AS following in vitro dissolution experiments. High resistance of the selected glass-ceramic samples against in vitro leaching has been demonstrated by minimal weight loss (<1%) and insignificant density change, even after 6 weeks of dissolution in artificial saliva. While XRD analysis reveals the change in surface texture of the crystalline phase, FT-IR analysis weakly indicated the Ca-P compound formation on the leached surface. The experimental measurements further indicate that the leaching of F(-), Mg(2+) ions from the sample surface commonly causes the change in the surface chemistry. Furthermore, the presence of (Ca, P, O)-rich mineralized deposits on the leached glass-ceramic surface as well as the decrease in Ca(2+) ion concentrations in the leaching solutions (compared to that in the initial AS solution) provide evidences of the moderate bioactive or mild biomineralisation behaviour of investigated glass-ceramics. 相似文献
19.
L. V. Morozova M. V. Kalinina M. Yu. Arsent’ev O. A. Shilova 《Inorganic Materials》2017,53(6):640-647
We have studied the influence of cryochemical and ultrasonic processing on the formation, structure, particle size, and thermal decomposition of xerogels in the ZrO2〈Y2O3〉–Al2O3 (20 wt %) system. Nanopowders of tetragonal-zirconia-based solid solutions with a high degree of tetragonality (c/a = 1.4366) have been synthesized. Al2O3 has been shown to slow down t-ZrO2 crystallite growth in the temperature range 600–1400°C. We have optimized nanopowder consolidation conditions, obtained nanoceramics stable to low-temperature “aging” in a humid medium, and investigated their physicochemical and mechanical properties. 相似文献
20.
Sabrina Seidel Marc Dittmer Wolfgang Wisniewski Wolfram Höland Christian Rüssel 《Journal of Materials Science》2017,52(4):1955-1968
High-strength, colorless glass–ceramics in the MgO/Al2O3/SiO2 system with high concentrations of ZrO2 and a great potential for technical application, e.g., as high-performance hard disc substrates, are investigated. ZrO2 concentrations from 6 to 9 mol% are added to a stoichiometric cordierite glass to investigate the influence of the concentration of the nucleating agent on the crystallization behavior and the mechanical properties. The phase formation and the microstructure of the glass–ceramics are studied using X-ray diffraction and scanning electron microscopy including electron backscatter diffraction. It is shown that the volume crystallization of ZrO2, a low-/high-quartz solid solution (low-/high-QSS), and spinel is accompanied by the surface crystallization of indialite. This phase offers a much smaller coefficient of thermal expansion than the other crystal phases, which may induce high compressive stresses in the surface layer of the glass–ceramics after cooling and seems to result in excellent mechanical properties of the material. Biaxial flexural strengths of up to 1 GPa were measured. Higher ZrO2 concentrations reduce the surface crystallization of indialite and decrease the mean size of the crystals resulting in a higher translucency. The volume-crystallizing phases and the mechanical properties of the glass–ceramics do not seem to be significantly affected by the analyzed ZrO2 concentrations. 相似文献