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1.
The limits of miscibility within a portion of the system Na2 O-ZnO-B2 O3 -SiO2 were determined at 650°, 800°, and 950°C. The miscibility gap at 800° and 950°C is a low dome, adjoining the zinc borosilicate miscibility gap. Below 755°C the dome intersects the Na2O-B2 O3 -SiO2 face of the phase diagram. The locus of this intersection is in agreement with literature data on the sodium borosilicate system. Estimated tie-line placement in the ZnO-B2 O3 -SiO2 miscibility gap at 1300°C resembles those reported for the corresponding CaO and SrO systems. The microscopic morphology of glasses with the weight composition xNa2 O-18ZnO-18B2 O3 -64SiO2 with 0≤×≤12 is described in detail. 相似文献
2.
The magnetic behavior of β-NaFeO2 precipitated in compositions along the Na2 SiO3 -Fe2 O3 join of the Na2 O-Fe2 O3 -SiO2 system is reported from magnetic susceptibility data and Moessbauer studies. The anomalous magnetic properties observed are discussed in terms of the possibility of the presence of super-paramagnetism. 相似文献
3.
Fine-particle beta sodium ferrite (β-NaFeO2 ), rather than α-Fe2 O3 , may be responsible for superparamagnetic behavior in a glass of composition (in mole fractions) 0.37Na2 O-0.26Fe2 O3 -0.37SiO2 . The 700°C isothermal section of the phase diagram of the Na2 O-Fe2 O3 -SiO2 system is given, showing a three-phase field bounded by Na2 SiO3 -NaFeO2 -Fe2 O3 ; there is no evidence for the existence (at 700°C) of compounds of molar composition 6Na2 O-4Fe2 O3 -5SiO2 or 2Na2 O-Fe2 O3 -SiO2 . The Moessbauer spectrum of β-NaFeO2 has an internal magnetic field of 487 kOe at room temperature. 相似文献
4.
The subliquidus miscibility gap in the system K2 O-B2 O3 -SiO2 has been determined for compositions with molar ratios SiO2 /B2 O3 <2 and T≥550°C. The shape of the miscibility gap is an elongated dome similar in form to, but less extensive than those in the lithium and sodium borosilicate systems. The consolute composition (molar) and temperature are estimated to be 4 ± 1 K2 O -30±8 B2 O3 -66±8 SiO2 and 629±5°C, respectively . 相似文献
5.
The binary isopleth Na2 O.B2 O3 -SiO2 of the Na2 O-B2 O3 SiO2 ternary system has been investigated. A phase diagram is presented based upon data from differential thermal analysis studies of prepared glasses and direct observation of the melting behavior using solid-state video imaging. Phase equilibria relations in the Na2 O-B2 O3 -SiO2 ternary system have been reassessed by combining information from this study with existing data from the literature. A revised liquidus surface for the ternary is presented in which the form of the isotherms is updated. 相似文献
6.
The liquidus surface for the high silica (>60 wt%) portion of the ternary system Na2 O-B2 O3 -SiO2 is presented. Determinations were made by quench runs and solubility studies. The compound, reedmergnerite, NaBSi3 O8 was not observed. Tridymite is the major primary phase . 相似文献
7.
To establish phase relations in the quaternary system Li2 O-Na2 O-Al2 O3 -SiO2 , the 50, 60, 70, 80, and 90 wt% isosilica planes were examined, mainly by quenching of quaternary glass compositions. 相似文献
8.
Using techniques developed by Goldschmidt and lately utilized by Foster, solid-state equilibria were studied in the system MgO-Al2 O3 -SiO2 ZrO2 . The ternary systems MgO-Al2 OrSiO2 and MgO-SiO2 -ZrO2 are the only faces of this four-phase system that have beep studied extensively. Compositions in each of the four faces were heated to temperatures below their fusion point and, after they had been cooled, they were examined by X rays to identify the phases present. After solid-state equilibria had been established or verified in the four faces of the system, quaternary compositions were studied to determine the Alkemade tetrahedra. 相似文献
9.
Debao Zhang Baoyu Chen Zhuping Liu Shunguang Li Lili Hu 《Journal of the American Ceramic Society》2004,87(12):2228-2231
Er3+ -doped sodium lanthanum aluminosilicate glasses with compositions of (90− x )(0.7SiO2 ·0.3Al2 O3 )· x Na2 O·8.2La2 O3 · 0.6Er2 O3 ·0.2Yb2 O3 ·1Sb2 O3 (in mol%) ( x = 12, 20, 24, 40, 60 mol%) were prepared and their spectroscopic properties were investigated. Judd–Ofelt analysis was used to calculate spectroscopic properties of all glasses. The Judd–Ofelt intensity parameter Ω t ( t = 2, 4, 6) decreases with increasing Na2 O. Ω2 decreases rapidly with increasing Na2 O while Ω4 and Ω6 decrease slowly. Both the fluorescent lifetime and the radiative transition rate increase with increasing Na2 O. Fluorescence spectra of the 4 I 13/2 to 4 I 15/2 transition have been measured and the change with Na2 O content is discussed. It is found that the full width at half-maximum decreases with increasing Na2 O. 相似文献
10.
Martin Boike Klaus Hilpert Franz Müller 《Journal of the American Ceramic Society》1993,76(11):2809-2812
Eight glass samples in the B2 O3 -SiO2 system with compositions from 20 to 90 mol% B2 O3 were prepared. The equilibrium vaporization was studied by Knudsen effusion mass spectrometry at temperatures between 1450 and 1500 K. B2 O3 ( g ) was the most abundant boron-containing species in the vapor; no silicon-containing gaseous species were detected. Thermodynamic activities of B2 O3 in the liquid were determined at 1475 K. Thermodynamic activities of SiO2 and integral excess Gibbs energies were estimated from the thermodynamic activities of B2 O3 . The thermodynamic data support the results obtained by other methods indicating the existance of a miscibility gap in the metastable liquid. 相似文献
11.
Alumina and gallia were substituted separately for Na2 O in amounts of 0.2, 0.5, 1.0, 1.5, 2.0, and 3.0 wt% in three Na2 O-SiO2 glass compositions (82, 84, and 86 wt% SiO2 ) within the immiscibility region. The immiscibility regions for each system extend to ∼1.5 mol% of the added oxide. In general, the addition reduced the immiscibility temperature ( T m ), but at the edge of the immiscibility region (82% SiO2 ) the Na2 O loss effect initially increased T m . A structural model of the miscibility of Al2 O3 added to silicate glasses is presented. 相似文献
12.
Immiscibility temperatures of Na2 O-B2 O3 -SiO glasses, with andwithout 1 mol% MoO3 , additions, were determined and the effect of MoO3 additions on the 65O°C immiscibility isotherms was established. In addition, immiscibility temperature and phase-separation morphology of an Na2 O-B2 O3 -SiO2 glass with progressive additions of MoO3 , were investigated. It was found that the addition of small amounts of MoO3 extends the immiscibility boundary of the system and raises the immiscibility temperature by ∼l8°C for each mol % MoO3 , addition. Analysis of phase-separation morphology suggests that the MoO3 , additions do not significantly alter the tie lines of phase separation in the system, although such additions cause a lowering of the viscosities and the glass-transition temperatures of these glasses. 相似文献
13.
Sashi Tandon Ranchhor D. Agrawal Madan L. Kapoor 《Journal of the American Ceramic Society》1994,77(4):1032-1036
The viscosity of sodium borate slags at high Na2 O concentrations (37.3 to 49.4 mol%) and high temperatures (1000° to 1300°C) follows an Arrhenius-type relationship. This relationship was also observed for sodium borate slags (mass% Na2 O/mass% B2 O3 = 0.86) containing CaO and CaF2 for the same temperature range. There has been a reduction in viscosity of the sodium borate slags (mass% Na2 O3 mass% B2 O = 0.53 to 0.86) with increase in Na2 O concentration. On adding CaO (10 to 50 mass%) to the sodium borate slag (mass% Na2 O/mass% B2 O3 = 0.86), the viscosity increased considerably, while an addition of CaF2 (S to 15 mass%) to the slag (30.9 mass% Na2 O3 35.8 mass% B2 O3 , 33.3 mass% CaO) decreased the viscosity. The average activation energies of Na2 O─B2 O3 , Na2 O─B2 O3 ─CaO3 and Na2 O─B2 O3 ─CaO─CaF2 slag systems have been estimated as 14.6, 124.7, and 41.4 kJ/mol, respectively, for the given composition ranges and 1000° to 1300°C temperature range. 相似文献
14.
Phase relations at liquidus temperatures in the system iron oxide-TiO2 -SiO2 have been determined in air. The equilibrium existence of the crystalline phases magnetite (ss), hematite (ss), pseudobrookite(ss), rutile(ss), and silica (tridy-mite or cristobalite) has been established. Three isobaric eutectic points are formed by the intersections of quaternary liquidus univariant lines of the system Fe-Ti-Si-O and the 0.21 atmosphere isobaric surface. The liquid misci-bility gaps present in the bounding "binary" systems iron oxide-Si02 and TiO2 -SiO2 extend across the composition triangle representing the "ternary" system iron oxide-TiO2 -SiO2 . Liquidus temperatures decrease within the two-liquid region from approximately l <57Qa C. in the system iron oxide-SiO2 and 1780°C. in the system Ti(VSiO2 to 1540°C. at the cristobalite-rutile(ss) boundary curve which bisects the two-liquid region. Paths of equilibrium crystallization of representative mixtures are discussed with reference to a simplified projection into the plane FeOFe2 O3 -TiO2 -SiO2 as well as in terms of the tetrahedron representing the system FeO-Fe2 O3 -TiO2 -SiO2 . 相似文献
15.
Phase relations in the system Na2 O· Al2 O3 -CaO· Al2 O3 -Al2 O3 at 1200°C in air were determined using the quenching method and high-temperature X-ray diffraction. The compound 2Na2 O · 3CaO · 5Al2 O3 , known from the literature, was reformulated as Na2 O · CaO · 2Al2 O3 . A new compound with the probable composition Na2 O · 3CaO · 8Al2 O3 was found. Cell parameters of both compounds were determined. The compound Na2 O · CaO-2Al2 O3 is tetragonal with a = 1.04348(24) and c = 0.72539(31) nm; it forms solid solutions with Na2 O · Al2 O3 up to 38 mol% Na2 O at 1200°C. The compound Na2 O · 3CaO · 8Al2 O3 is hexagonal with) a = 0.98436(4) and c = 0.69415(4) nm. The compound CaO · 6Al2 O3 is not initially formed from oxide components at 1200°C but behaves as an equilibrium phase when it is formed separately at higher temperatures. The very slow transformation kinetics between β and β "-Al2 O3 make it very difficult to determine equilibrium phase relations in the high-Al2 O3 part of the diagram. Conclusions as to lifetime processes in high-pressure sodium discharge lamps can be drawn from the phase diagram. 相似文献
16.
Takashi Wakasugi Rikuo Ota Jiro Fukunaga 《Journal of the American Ceramic Society》1992,75(11):3129-3132
In order to evaluate the crystallization tendency of glasses, the ratio of the crystallization temperature to the liquidus temperature ( T c / T L ) was obtained by DTA measurement for the Na2 O–B2 O3 and Na2 O–B2 O3 –Al2 O3 systems. The critical cooling rate for glass formation ( Q *) was also measured. The measurements were performed in the composition range of (100 − x )Na2 O–( x )B2 O3 , ( x = 25–35 and 60–100 mol%), and (100 − y )0.5Na2 O·0.5B2 O3 −( y )Al2 O3 , ( y = 6–34 mol%). The relationship between T c / T L and Q * was discussed. A linear relationship between T c / T L and log Q * for these systems was found. Furthermore, the relationship between T c / T L and Q * was verified by computer simulation based on the crystallization kinetics of glass or supercooled liquid. 相似文献
17.
E. A. GIESS B. A. SCOTT B. L. OLSON G. BURNS D. F. O'KANE 《Journal of the American Ceramic Society》1970,53(1):14-17
The extents of the liquidus and solidus fields were determined for tungsten bronze-type solid solutions in the Na2 O-BaO-Nb2 O5 system by DTA and melt crystal growth experiments. Bronze-type solid solutions exist to 7.1Na2 O-34.9BaO-58Nb2 O5 in the Nb2 O5 -rich region and from 12Na2 O-38BaO-50Nb2 O5 to 4.6Na2 O-45.4BaO-50Nb2 O5 along the NaNbO2 -BaNb2 O6 join, which includes NaBa2 Nb5 O15 =10Na2 O-40BaO-50Nb2 O6 . There is little, if any, solid solubility of compositions with a deficiency of Nb2 O5 . Curie temperatures decline rapidly and dielectric constant peaks broaden with Nb2 O5 substitution because the Nb:O ratio becomes greater than the octahedral 1:3 ratio. Useful ferroelectrics exist along the NaNbO3 -BaNb2 O6 join where the Nb:O ratio is 1:3. Large striae-free crystals, with less optical scattering than Czochralski-grown crystals, were grown from unseeded Na2 O-rich melts (e.g. 15Na2 O-37.5BaO-47.5Nb2 O5 ) cooled from 1520° to 1300°C at 2°C/h. Annealing effects on these crystals whose compositions lie on the NaNbO3 -BaNb2 O6 join are discussed. 相似文献
18.
G. Bhattacharya S. Zhang D. D. Jayaseelan W. E. Lee 《Journal of the American Ceramic Society》2007,90(1):97-106
Lithium borate (Li2 B4 O7 ) and sodium borate (Na2 B4 O7 ) mineralize spinel formation from stoichiometric MgO and Al2 O3 between 1000° and 1100°C. Mineralization with both compounds is shown to be mediated by B-containing liquids which form glass on cooling. However, the liquid compositions depend on the type of mineralizer and temperature, suggesting that templated grain growth or dissolution–precipitation mechanisms are operating, one dominating over the other under certain conditions. Na2 B4 O7 -mineralized compositions show predominantly templated grain growth at 1000°C, which changes to dissolution–precipitation at 1100°C, whereas Li2 B4 O7 -mineralized compositions show dissolution–precipitation from 1000°C. Li2 B4 O7 is a stronger mineralizer as spinel formation is complete with 3 wt% Li2 B4 O7 at 1000°C and with ≥1.5 wt% addition at 1100°C, whereas Na2 B4 O7 -mineralized compositions are found to retain some unreacted corundum even at 1100°C. 相似文献
19.
Subsolidus phase relations in the system Na2 O-Bi2 O3 -TiO2 at 1000°C were investigated by solid-state reaction techniques and X-ray diffraction methods. Five ternary compounds were observed in the system: Na0.5 Bi4.5 Ti4 O15 ; Na0.5 Bi0.5 TiO3 ; a cubic pyrochlore solid solution composed of xNa2 O.25Bi2 O3 .(75−;x) TiO2 where x is 2.5 to 3.75; a new compound Na0.5 Bi8.5 Ti7 O27 indexed with the orthorhombic cell of a = 5.45, b = 5.42, and c = 36.8 Å; and an unidentified phase with the probable composition NaBiTi6 O14 . 相似文献
20.
Takeshi Takamori 《Journal of the American Ceramic Society》1990,73(1):158-160
The Bi2 O3 -rich side of the system Bi2 O3 -SiO2 was studied with powder X-ray diffraction and differential thermal analysis. In the composition 6Bi2 O3 . x SiO2 , the metastable γ phase (bcc) was observed to exist over the range of 0 < x ≤ 1. In most of the compositions studied, metastable phases of water-quenched melts transformed into another metastable phase before reaching stable phases. A modification of the phase diagram is proposed. 相似文献