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1.
This paper describes the synthesis and spectroscopic studies of the glass system, 20Na2O-(20-x) ZnO-xZnF2-60B2O3(x = 0, 5, 10, 15, 20), prepared by melt quenching method. The analyses of DSC and XRD did not show the crystallinity of the
glass sample. 11B MAS-NMR shows the presence of sharp peak around −14 ppm. From the IR studies, the broadening of the peak around 1200–1400
and 800–1100 cm−1 shows the presence of mixed linkages like B-O-B, B-O-Zn in the network. 相似文献
2.
A. V. Egorysheva V. D. Volodin A. A. Chistyakov Yu. A. Kuzishchin V. M. Skorikov T. D. Dudkina 《Inorganic Materials》2010,46(12):1384-1390
We have prepared europium-doped BaO-Bi2O3-B2O3 glasses and investigated the doping effect on the main physicochemical properties and local structure of the glasses. Using
Judd-Ofelt analysis, we calculated intensity parameters (Ω2, Ω4, and Ω6), spontaneous emission probabilities, the radiative lifetime, luminescence branching factors, the quantum yield of luminescence,
and the stimulated emission cross sections for 5
D
0 → 7
F
J
transitions. 相似文献
3.
We gave studied the crystallization behavior of 30BaO · 25Bi2O3 · 45B2O3 glasses doped with Eu2O3 to different levels. At a Eu2O3 content of 7 mol % or higher, the glasses undergo volume crystallization. The only precipitating phase is a solid solution
between europium and bismuth oxides. With increasing europium concentration in the glass, the structure of the crystallites
changes from cubic to rhombohedral. We have investigated the morphology, physicochemical properties, and luminescence spectra
of the glasses and glass-ceramics. 相似文献
4.
The physicochemical properties of BaO-Bi2O3-B2O3 glasses have been studied. The effect of KBF4 additions on the properties of the glasses has been examined. The transmission of the glasses has been correlated with their local structure and composition. 相似文献
5.
L. A. Trusov D. D. Zaitsev P. E. Kazin Yu. D. Tret’yakov M. Jansen 《Inorganic Materials》2009,45(6):689-693
Glasses with nominal compositions 11SrO · 5.5Fe2O3 · 4.5Al2O3 · 4B2O3 (1) and 15SrO · 5.5Fe2O3 · 4.5Al2O3 · 4B2O3 (2) were prepared by rapidly quenching oxide melts between counterrotating steel rollers. The glasses were then heat-treated in the range 650–950°C to produce glass-ceramic samples. The samples were characterized by X-ray diffraction, electron microscopy, and magnetic measurements. The phase composition of the glass-ceramics was determined, and their microstructure and magnetic properties were studied. The annealing temperature was shown to have a strong effect on the coercivity of the materials, which reaches 650 and 570 kA/m for compositions 1 and 2, respectively. 相似文献
6.
A. V. Egorysheva V. D. Volodin V. M. Skorikov G. Yu. Yurkov N. I. Sorokin 《Inorganic Materials》2010,46(4):434-438
This work examines the effect of KBF4 additions on the crystallization behavior of glasses based on the multicomponent systems MO-Bi2O3-B2O3 with M = Ca, Sr, and Ba. The glass-ceramic composites obtained contain a δ-Bi2O3-based crystalline phase with a crystallite size of ≃7 nm, evenly distributed over the glass matrix. The 400°C electrical
conductivity of the nanocomposites reaches 2 × 10−4 S/cm, and the activation energy is 1.1 eV, typical of anion conduction. These values are comparable to those reported for
δ-Bi2O3 ceramics. 相似文献
7.
The 600°C (subsolidus) section of the CaO-Bi2O3-B2O3 phase diagram has been studied by x-ray diffraction and differential thermal analysis. A new calcium bismuth borate of composition CaBi2B4O10 has been identified, and the existence of CaBi2B2O7 has been confirmed. According to T-x phase diagram data, these compounds form peritectically at 700±5 and 783±5°C, respectively. 相似文献
8.
We have studied the optical absorption and luminescence spectra of 45Na2O · xNb2O5 · (55 − x)P2O5 glasses containing 5, 10, 20, 25, 30, and 35 mol % Nb2O5. The results indicate that the absorption band around 26000 cm−1, responsible for the yellow color of the glasses, is due to the [Nb(5+)--O−] center and disappears upon secondary heat treatment. Heat treatment of europium-doped glasses increases the concentration
of Eu3+ centers in an asymmetric environment, which is accompanied by an increase in luminescence efficiency. The reason for this
is that the Eu3+ ions are located outside the niobate subsystem of the glass matrix. The europium in the glasses studied acts as a protector
ion. 相似文献
9.
10.
Semiconducting glasses of the Fe2O3-Bi2O3-K2B4O7 system were prepared by the press-quenching method and their dc conductivity in the temperature range 223–393 K was measured. The glass transition temperature values (Tg) of the present glasses were larger than those of tellurite glasses. This indicates a higher thermal stability of the glass in the present system. The density for these glasses was consistent with the ionic size, atomic weight and amount of different elements in the glasses. Mössbauer results revealed that the relative fraction of Fe increases with increasing Fe2O3 content. Electrical conductivity showed a similar composition dependency as the fraction of Fe. The glasses had conductivities ranging from 10 to 10 Scm at temperatures from 223 to 393 K. Electrical conduction of the glasses was confirmed to be due to non-adiabatic small polaron hopping and the conduction was primarily determined by hopping carrier mobility. 相似文献
11.
Mohamed M. Gomaa Hussein Darwish Saad M. Salman 《Journal of Materials Science: Materials in Electronics》2008,19(1):5-15
The ac electrical properties of some lithium silicate glasses and glass-ceramics containing varying proportions of Y2O3 and/or Fe2O3 were measured to investigate their electronic hopping mechanism. There is a clear variation of these properties with composition.
The obtained results were related to the concentration and role of Y2O3 and/or Fe2O3 in the lithium silicate glass structure. In crystalline solids the electrical properties data obtained were correlated to
the type and content of the mineral phases formed as indicated by X-ray diffraction analysis (XRD).
The conductivity, dielectric constant and dielectric loss of the studied glasses were studied using the frequency response
in the interval 30 Hz–100 KHz and the effect of compositional changes on the measured properties was investigated. The measurements
revealed that the electrical responses of the samples were different and complex. The addition of Y2O3 generally, decreased the ac conductivity, dielectric constant and dielectric losses of the lithium silicate glasses. The
addition of Fe2O3 in Y2O3-containing glasses increases the conductivity, while, the dielectric constant and dielectric losses were found to be decreased.
However, the addition of Fe2O3 instead of Y2O3 led to decrease the ac conductivity and increased their dielectric constant and dielectric losses.
The obtained data were argued to the internal structure of the lithium silicate glass and the nature or role-played by weakness
or rigidity of the structure of the sample.
Lithium disilicate-Li2Si2O5, lithium metasilicate-Li2SiO3, two forms of yttrium silicate Y2Si2O7 & Y2SiO5, iron yttrium oxide-YFeO3, lithium iron silicate-LiFeSi2O6 and α-quartz phases were mostly developed in the crystallized glasses.
The conductivity of the crystalline materials was found to be relatively lower than those of the glass. At low frequency,
as the Y2O3 content increased the ac conductivity, dielectric constant and dielectric loss data of the glass-ceramics decreased. However,
the addition of Fe2O3 to the Y2O3 containing glass-ceramic led to increase the conductivity. The addition of high content of Fe2O3 instead of Y2O3 in the glass ceramic led to increase the ac conductivity. 相似文献
12.
Josef Jirák Ladislav Koudelka Jaroslav Pospíšil Petr Mošner Lionel Montagne Laurent Delevoye 《Journal of Materials Science》2007,42(20):8592-8598
Glasses of the ternary system ZnO–Bi2O3–P2O5 were prepared and studied in two compositional series 50ZnO–xBi2O3–(50 − x)P2O5 and (50 − y)ZnO–yBi2O3–50P2O5. Two distinct glass-forming regions were found in the 50ZnO–xBi2O3–(50 − x)P2O5 glass series with x = 0–10 and 20–35 mol.% Bi2O3. All prepared Bi2O3-containing glasses reveal a high chemical durability. Small additions of Bi2O3 (∼5 mol.%) improve thermal stability of glasses. All glasses crystallize on heating within the temperature range of 505–583 °C.
Structural studies by Raman and 31P MAS NMR spectroscopies showed the rapid depolymerisation of phosphate chains within the first region with x = 0–15 and the presence of isolated Q0 phosphate units within the second region with x = 20–35. Raman studies showed that bismuth is incorporated in the glass structure in BiO6 units and their vibrational bands were observed within the spectral region of 350–700 cm−1. The evolution of properties and the spectroscopic data are both in accordance with a network former effect of Bi2O3. 相似文献
13.
A series of glass comprising of SiO2–MgO–B2O3–Y2O3–Al2O3 in different mole ratio has been synthesized. The crystallization kinetics of these glasses was investigated using various
characterization techniques such as differential thermal analysis (DTA), thermo gravimetric analysis (TGA), X-ray diffraction
(XRD), and scanning electron microscopy (SEM). Crystallization behavior of these glasses was markedly influenced by the addition
of Y2O3 instead of Al2O3. Addition of Y2O3 increases the transition temperature, T
g, crystallization temperature, T
c and stability of the glasses. Also, it suppresses the formation of cordierite phase, which is very prominent and detrimental
in MgO-based glasses. The results are discussed on the basis of the structural and chemical role of Y3+ and Al3+ ions in the present glasses. 相似文献
14.
The high-temperature Raman spectra recording technique was found applicable also to study luminescence of atoms and individual molecular groups in vapors over some overheated molten compounds. Sodium atomic luminescence excited with a yellow (578.2 nm) copper vapor laser line was detected in vapors over overheated molten Na2WO4 and Na2O-BaO-B2O3 system. The possibility of recording the sodium doublet spectrum by excitation with the 578.2 nm copper vapor laser line in vapors of any melts containing sodium was shown. Overheated melts in the Na2O-BaO-B2O3 system disproportionate and lose boron oxide as evidenced by the recording of luminescent spectra of BO2 molecular radicals in vapors over relevant melts. 相似文献
15.
In the sodium cadmium phosphate glasses, the effect of diffused alumina from alumina crucible has been assessed by measuring various properties such as mass density, refractive index, optical bandgap and dc conductivity. The results of measurements corresponding to glasses prepared in alumina crucible have been compared with those of glasses prepared in platinum crucible with and without adding Al2O3. The Optical bandgap and direct current (dc) electrical conductivity of the Na2O-CdO-P2O5 glasses prepared in alumina and platinum crucibles have been determined at room temperature. These glasses have also been electrically characterised in the temperature range 293–423 K. Activation energy Ea of the samples prepared in alumina crucible lies in the range 0.60–0.96 eV whereas it stands in the range of 0.57–0.94 eV for the samples prepared in platinum crucible. 相似文献
16.
The thermoelectric power and d.c electrical conductivity of x V2O5⋅40CaO⋅(60−x)P2O5 (10 ≤ x ≤ 30) glasses were measured. The Seebeck coefficient (Q) varied from +88 μ V K−1 to −93 μV K−1 as a function of V2O5 mol%. Glasses with 10 and 15 mol% V2O5 exhibited p-type conduction and glasses with 25 and 30 mol% V2O5 exhibited n-type conduction. The majority charge carrier reversal occurred at x = 20 mol% V2O5. The variation of Q was interpreted in terms of the variation in vanadium ion ratio (V5 +/V4 +). d.c electrical conduction in x V2O5⋅40CaO⋅(60−x)P2O5 (10 ≤ x ≤ 30) glasses was studied in the temperature range of 150 to 480 K. All the glass compositions exhibited a cross over from
small polaron hopping (SPH) to variable range hopping (VRH) conduction mechanism. Mott parameter analysis of the low temperature
data gave values for the density of states at Fermi level N (EF) between 1.7 × 1026 and 3.9 × 1026 m−3 eV−1 at 230 K and hopping distance for VRH (RVRH) between 3.8 × 10−9m to 3.4 × 10−9 m. The disorder energy was found to vary between 0.02 and 0.03 eV. N (EF) and RVRH exhibit an interesting composition dependence. 相似文献
17.
New solid solutions, Bi2?x?y Tm x Nb y O3+δ, with tetragonal and cubic structures have been synthesized in the Bi2O3-Tm2O3-Nb2O5 system, and their electrical conductivity has been measured at temperatures from 670 to 1020 K. The 1020-K conductivity of the tetragonal solid solution Bi1.8Tm0.15Nb0.05O3+δ is comparable to that of Bi1.75Tm0.25O3, the best conductor in the Bi2O3-Tm2O3 system. 相似文献
18.
Choon-Woo Nahm 《Journal of Materials Science》2005,40(23):6307-6309
19.
M. A. Ouis F. H. ElBatal 《Journal of Materials Science: Materials in Electronics》2018,29(22):18913-18922
Undoped and Bi2O3-doped glasses from the system Na2O–CdO–P2O5 were prepared and studied through investigating their optical and FTIR spectra before and after gamma irradiation beside measuring their thermal expansion properties. Optical spectra reveal distinct UV absorption with additional peaks upon introducing Bi2O3 added with different concentrations from 1 to 7.5%. The UV absorption of the undoped sample is related to trace iron impurities while the extended UV absorption peaks are correlated with absorption of Bi3+ ions. FTIR spectra show condensed phosphate groups (Q2, Q3 units) beside the sharing of bismuth ions in their vibrational sites. Gamma irradiation causes limited changes in the UV spectra but involves the generation of an induced visible band in the undoped glass. These changes are assumed to be due to some suggested photochemical reactions on the trace iron impurities and the formation of an induced visible (POHC) band on the phosphate network. Careful inspection of the selected deconvoluted spectra for the undoped glass and doped (7.5 wt%) supports the introduced assumptions. The thermal expansion parameters are correlated with the type of bonding of bismuth ions within the network structure. 相似文献
20.
In this study, pure Na2Ca2Si3O9 was synthesized by a sol-gel method, and Na2Ca2Si3O9 cuboids and disks were prepared by uniaxial pressing and calcining at 700 °C. The porosity and mechanical strength of the Na2Ca2Si3O9 cuboids were measured, and the results showed that the Na2Ca2Si3O9 cuboids were porous with an average porosity of 44%, and the 3-point bending strength of the cuboids was 6.08 MPa. The in vitro bioactivity of Na2Ca2Si3O9 was carried out by soaking Na2Ca2Si3O9 disks in simulated body fluid (SBF). The results showed that hydroxyapatite (HA) formed on the surface of Na2Ca2Si3O9 samples after soaking for 1 day, which indicated good bioactivity of Na2Ca2Si3O9. 相似文献