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1.
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
2.
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
3.
An investigation was made of the effect of TiO2 on the glassforming region and on the physical properties of glasses in the system Na2 O-B2 O3 -SiO2 TiO2 . Glasses containing up to 45 mole % TiO2 may be formed with an alkali content of 30 mole %. At lower alkali contents (10 mole % Na2 O) glasses may be formed containing up to 22 mole % TiO2 . The way in which the coefficient of linear thermal expansion and the transformation and softening temperatures are affected by TiO2 additions has been determined. 相似文献
4.
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
5.
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
6.
The system CaO-Ta2 O3 -SiO2 was studied using a combination of hot-stage microscopy and the quenching technique. Primary crystallization fields were defined for the various calcium silicates, and for the calcium tantalates: CaO·2Ta2 O5 , CaO·Ta2 O5 , 2CaO·Ta2 O5 , and 4CaO·Ta2 O5 . A congruently melting ternary compound 10CaO·Ta2 O5 ·6SiO2 , isostructural with the mineral niocalite, is the only ternary phase in the system. A large twoliquid region extends across the system from the CaO-SiO2 binary to within 1 wt% of the Ta2 O3 -SiO2 binary but does not cut it, in marked contrast to the analogous CaO-Nb2 O5 -SiO2 system. Other somewhat unexpected differences were noted between these systems. 相似文献
7.
PETER TAYLOR ALLAN B. CAMPBELL DERREK G. OWEN 《Journal of the American Ceramic Society》1983,66(5):347-351
The limits of miscibility at 650°C were determined for compositions with the mole ratio SiO2 /B2 O3 =1.07 in the systems X2 O-MO-B2 O3 -SiO2 (X = Na,K; M = Mg,Ca,Ba) and Na2 O-MgO-BaO-B2 O3 -SiO2 . The form of the miscibility gaps in the quaternary systems is similar to that previously described for the system Na2 O-ZnO-B2 O3 -SiO2 . The topography of miscibility gaps in systems of this type is discussed in detail. The extent of the miscibility gap is correlated with the polarizing power of each cation, X and M (Na > K and Zn ≅ Mg > Ca > Ba) both among the seven quaternary systems and within the single five-component system examined. The possibility of using empirical correlations observed among the quaternary systems to predict the behavior of other compositions, or of more complex systems, is explored. 相似文献
8.
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
9.
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
10.
J. D. HODGE 《Journal of the American Ceramic Society》1984,67(3):183-185
A subsolidus phase diagram for the system Li2 O-Na2 O-Al2 O3 at 1500°C is presented. Unlike the analogous system MgO-Na2 O-Al2 O3 , β" was the only ternary compound observed in the section of the lithia-based system examined in this study. A fairly extensive region of β solid solution was found. In contrast, the range of compositions where β" exists is small and does not extend into the Na2 O-Al2 O3 binary. 相似文献
11.
Tentative phase relations in the binary system BnOa-A12 O3 are presented as a prerequisite to the understanding of the system Li2 O-B2 O3 -Al2 O3 . Two binary compounds, 2A12 O3 .B2 O3 and 9A12 O3 .-2B2 O3 , melted incongruently at 1030° f 7°C and about 144°C, respectively. Two ternary compounds were isolated, 2Li2 O.A12 O3 .B2 O3 and 2Li2 O. 2AI2 O3 . 3B2 03 . The 2:1:1 compound gave a melting reaction by differential thermal analysis at 870°± 20° C, but the exact nature of the melting behavior was not determined. The 2:2:-3 compound melted at 790°± 20° C to Liz O.-5Al2 O3 and liquid. X-ray diffraction data for the compounds are presented and compatibility triangles are shown. 相似文献
12.
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
13.
Phase-equilibrium studies of the liquidus surface of the Na2 O-BaO-SiO2 system are presented. The system contains 5 ternary compounds, Na2 Ba4 Si10 O25 , Na2 Ba4 Si2 O6 , Na2 Ba2 Si2 O7 , X (probably Na2 Ba18 Si28 O75 ), and Y (probably Na2 Ba45 Si73 O192 ), all of which melt incongruently. Twenty-three liquidus invariant points, including 13 peritectics, 4 eutectics, and 6 thermal maxima, were located. Metastable crystallization reactions are commonly encountered, and some of the metastable equilibria are described. 相似文献
14.
Phase relations in the system Li2 O–B2 O3 –SiO2 were studied by quenching and solid-state reactions. No ternary compounds were detected in the portion of the system containing less than 53% Li2 O. Compatibility triangles were formed from the binary borate and silicate compounds. Liquidus data obtained by quenching are reported for four joins, Li2 O·2SiO2 –Li2 O·2B2 O3 , Li2 O·SiO2 -Li2 O·2B2 O3 , Li2 O·SiO2 -Li2 O·B2 O3 , and Li2 O·2B2 O3 -SiO2 . The last join cuts across the two-liquid region and is not a true binary system. Some probable ternary invariant points were located in the portion of the system which was quenchable to glass and adjacent to the two-liquid region. Further data on the previously reported immiscible liquid formation are given and the significance is discussed. Data on the thermal expansion behavior of certain glasses are presented. 相似文献
15.
Liǵuid us and subsolidus phase relations were studied using the quenching technique. The system contains four ternary compounds stable to liquidus temperatures: Na2 TiSi4 O11 , Na2 TiSi2 O7 , Na2 TiSiO5 , and Na2 Ti2 Si2 O9 . Six eutectics, eight peritecties, and eight thermal maxima were located and a region of liquid immiscibility was delineated. X-ray powder data are given for the stable and metastable crystalline phases. Glass-transition temperatures were determined by thermal analysis. The relation between physical properties of melts and glasses and the configuration of the liquidus is discussed. 相似文献
16.
MARIA ISABEL NIETO ALICIA DURAN JOSE MARIA FERNANDEZ NAVARRO JOSE LUIS OTEO MAZO 《Journal of the American Ceramic Society》1984,67(4):242-244
Infrared spectra of glasses of the system R2 O-B2 O3 -SiO2 were investigated. The extinction coefficients of the hydroxyl absorption band ("free OH") were calculated by a method proposed for alkali borate glasses. The results confirmed the applicability of this method to homogeneous and phase-separated alkali borosilicate glasses. The variation of the hydroxyl absorption band position was interpreted according to the structural characteristics of the studied glasses. 相似文献
17.
P. L. ROEDER F. P. GLASSER† E. F. OSBORN 《Journal of the American Ceramic Society》1968,51(10):585-593
Liquidus phase equilibrium data are presented for the system Al2 O3 -Cr2 O3 -SiO2 . The liquidus diagram is dominated by a large, high-temperature, two-liquid region overlying the primary phase field of corundum solid solution. Other important features are a narrow field for mullite solid solution, a very small cristobalite field, and a ternary eutectic at 1580°C. The eutectic liquid (6Al2 O3 -ICr2 O3 -93SiO2 ) coexists with a mullite solid solution (61Al2 O3 -10Cr2 O3 -29SiO2 ), a corundum solid solution (19Al2 O3 -81Cr2 O3 ), and cristobalite (SO2 ). Diagrams are presented to show courses of fractional crystallization, courses of equilibrium crystallization, and phase relations on isothermal planes at 1800°, 1700°, and 1575°C. Tie lines were sketched to indicate the composition of coexisting mullite and corundum solid solution phases. 相似文献
18.
CECIL M. JONES II 《Journal of the American Ceramic Society》1971,54(7):347-349
A technique for growing α-Al2 O3 crystals is described in which Na2 O·11Al2 O3 is dissolved in a liquid of composition Na2 O·4TiO2 ·3Al2 O3 . Alpha Al2 O3 is precipitated as Na2 O evaporates from the system; Na2 O·11Al2 O3 serves as a source of Al2 O3 , and Na2 O in the liquid. The content of solids in the mixture is always such that it does not melt completely. The size of the α-Al2 O3 crystals grown is related to the Na2 O content of the composition. Crystals as large as 4000 by 3000 μm in the α-axis direction and 500 μm in the c -axis direction have been grown. 相似文献
19.
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
20.
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