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1.
《Journal of solid state chemistry》1991,92(1):170-177
Phase relations in the vicinity of the YBa2Cu3O6+x in the CuO-rich part of the YBaCuO system were studied by the equilibration and quenching technique. At 950°C, the system is characterized by the large number of solid four-phase combinations. The oxygen potential as a function of temperature for two four-phase combinations, i.e., YBa2Cu3O6+x + BaCuO2 + BaCu2O2 + Y2BaCuO5 and YBa2Cu3O6+x + BaCu2O2 + Y2BaCuO5 + Cu2O, were studied by means of solid state EMF measurements. At higher oxygen potentials the pair of YBa2Cu3O6+x and Y2BaCuO5 is stable in contact with BaCuO2. At lower oxygen pressures this pair coexists in equilibrium with BaCu2O2 or Cu2O. 相似文献
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《Ceramurgia International》1978,4(3):104-107
Hydrothermal reactions in the systems calcite-quartz and magnesite-quartz have been studied over the temperature range 200°C to 600°C and the steam pressure range 1.5 to 70 MPa. In the calcite-quartz system, a hydrothermal reaction was found to occur at temperatures in excess of 450°C to form wollastonite. In the magnesite-quartz system, at temperatures above 300°C, formation of talc was observed in all compositions studied, with some formation of serpentine evident at higher magnesite compositions. Above 450°C and at magnesite contents above 80%, talc and forsterite formed. In all cases, the reaction mechanism appears to be the displacement of CO2 by a mobile silica species. To assess the potential utilization of these reactions in ceramic manufacture, a series of samples was made from carefully graded mixtures and their compressive strengths were measured. Mixtures of calcite and quartz developed a maximum strength of 18±2 MPa at 300°C. In the magnesite-quartz system, the strength was found to increase from 11±2 MPa at 200°C to 31±2 MPa at 300°C and 30±2 MPa at 500°C. The strength rose with time of treatment in each case, reaching a maximum at about forty hours, after which no further increase in strength with time was evident. 相似文献
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《Journal of solid state chemistry》1986,63(2):129-138
Two new oxyborate compounds were synthesized during a study of the phase relationships between the pinakiolite-ludwigite series of compounds. The structural topologies of these previously unreported materials have been determined experimentally by comparing calculated with observed electron microscope images. Both of these structures are very similar to each other, and also closely related to pinakiolite which consists of flat walls of edge-sharing octahedra connected to zigzag chains of octahedra by triangular BO3 groups. The two new structures contain similar infinite walls which are separated by slabs of octahedra that are wider than the zigzag chains found in pinakiolite. A new series of structurally related oxyborate compounds can be envisaged and are described. 相似文献
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A survey has been made of HOH bending frequencies in water-containing solids and liquids, using data from the literature and from the author's laboratory. After the effects of hydrogen bonding and dynamic coupling have been allowed for, HOH bending frequencies are found to be lowered by cation—water interactions. This frequency lowering increases statistically with increasing cation charge and with decreasing cation size. 相似文献
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《Journal of solid state chemistry》1987,71(1):103-108
A systematic study of compound and solid-solution formation in the system Li2ONb2O5TiO2 has been made. Several solid-solution series, based on LiNbO3, LiNb3O8, Li2Nb28O71, Li2TiO3, phase M, Li2Ti3O7, and TiO2, have been characterized. In all cases, the principal solid-solution mechanism appears to involve stoichiometric formulae with constant overall cation content. One new phase, of approximate formula Li13TiNb5O21, has been prepared. A subsolidus phase diagram for the ternary system is presented. 相似文献
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《Journal of the Less Common Metals》1979,63(2):171-179
The HfNi and ZrNi systems have been examined in the region 65 – 80 at.% Ni by microscope and X-ray analyses.In the HfNi system the following intermediate phases were observed: Hf3Ni7, Hf8Ni21, HfNi3(h. t.), HfNi3(l. t.) and Hf2Ni7. Hf3Ni7, which is formed peritectically at 1250 ± 20 °C, decomposes eutectoidally at 1016 ± 3 °C into Hf7Ni10 and HfNi3(l. t.). Hf8Ni21 is stable from 1300 ± 20 °C, where it forms peritectically, to 1175 ± 10 °C where it decomposes eutectoidally into Hf3Ni7 and HfNi3(l. t.). HfNi3(h. t.) is a high temperature phase, forming peritectically at 1350 ± 20 °C and transforming into HfNi3(l. t.) below 1200 ± 10 °C. Hf2Ni7 melts congruently. A eutectic between Hf7Ni10and Hf3Ni7 occurs at 1190 ± 10 °C.In the ZrNi system only one phase forming peritectically exists; this is Zr8Ni21, which is stable at least down to 800 °C. ZrNi3 is formed in a reaction between Zr8Ni21 and Zr2Ni7 at 920 ± 10 °C. Crystallographic data for the intermediate phases in the HfNi and ZrNi systems in the region 65–75 at.% Ni are presented. 相似文献
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N. V. Barkovskii 《Russian Journal of General Chemistry》2016,86(8):1787-1793
Fundamentally different behavior of Ba–Bi–O (Ba : Bi = 11 : 4, 1 : 1, 2: 3, and 1 : 5 mol/mol) and KnBamBim+nOy (m = n = 1, 2,...; exhibiting superconducting properties with Tc = 28–32 K) oxides and BaO2 in hydrolysis reactions has been revealed by means of potentiometry and chemical analysis. Products of the oxides treatment with water do not contain H2O2, evidencing the absence of peroxide ions in their structure. The perovskite-type barium-bismuth(III) oxides are completely hydrolyzed into Ba(OH)2 and Bi2O3 at room temperature. 相似文献
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《European Journal of Solid State and Inorganic Chemistry #》1998,35(8-9):591-594
It has been found experimentally that phase diagram for the system Bi2O3CaOSrOCuO in SrO-rich region at 850°C in the open air includes three elementary tetrahedra: CaOSrOSr6Bi2O11Sr2CuO3, CaOSr2CuO3Sr6Bi2O11Sr3,5Ca0,5Bi2O7 and Sr3Bi2O6Sr6Bi2O11Sr3,5Ca0,5Bi2O7 Sr2CuO3. In the considered interval of corresponding oxide concentrations quaternary oxides are not formed under the above conditions. 相似文献
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《Thermochimica Acta》1979,29(2):327-332
Sintering studies of WC-11%Co samples have been performed in a dilatometer. The temperature dependence of the shrinkage and the shrinkage rate during heating and isothermal treatment has been determined using computer evaluation. The relative magnitude of the densification in the solid and liquid states, respectively, has been determined and correlated to the CoWC phase diagram. Furthermore, some structural changes occurring under decarburizing conditions have been explained. Mechanisms for solid and liquid state sintering are presented. 相似文献
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《Journal of Inorganic and Nuclear Chemistry》1978,40(3):503-505
The reaction behaviors between some complex fluorides of MFUF4 system (M = Rb or Cs) and fluorine were investigated. In all the cases, uranium was oxidized to hexa-valent state at the temperatures between 300 and 500°C and M2UF8 type complex was formed, except for the cases of 3MF·UF4 type complexes. In the fluorinations of 3MF·UF4, products with the composition of M3UF9 were formed. A change in the stability of RbFUF6 systems with RbF/UF6 ratio was also investigated. 相似文献
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《Tetrahedron letters》1986,27(5):581-584
Amines, especially imidazole, were found to be essential in the meso-tetraphenylporphinatoiron (III) promoted demethylation of N, N-dimethylaniline N-oxide through the Polonovski type reaction and in the cumene hydroperoxide dependent oxidative demethylation of N, N-dimethylaniline in dichloromethane. When benzenethoil was used instead of these amines, deoxygenation of N, N-dimethylaniline N-oxide took place very readily 相似文献
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《Journal of Inorganic and Nuclear Chemistry》1978,40(7):1375-1381
Portions of the cesium-uranium-oxygen system have been investigated between 873 and 1273 K and a phase diagram has been constructed using our data and the data of other workers in the field. A consistent set of measured and estimated thermodynamic data for cesium uranates has been used to calculate the equilibrium cesium partial pressure and the equilibrium oxygen partial pressure over two and three phase regions in the CsUO system. For a given temperature, the equilibrium cesium partial pressure in a two phase region decreases as the equilibrium oxygen partial pressure increases. 相似文献
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M. Natália D. S. Cordeiro Roberto Cammi José A. N. F. Gomes Jacopo Tomasi 《Theoretical chemistry accounts》1992,82(3-4):165-187
The interaction energyE of the systems Cu+-H2O and Cl–-H2O has been computed over a wide range of distances and orientations with the MINI-1 basis set in the SCF approximation. The interaction energy has been decomposed according to the Kitaura-Morokuma scheme, with and without counterpoise (CP) corrections to the basis set superposition error. The importance of this correction is analysed by its effect upon Monte Carlo calculations of the Cu+-water and Cl–-water systems, using two-body potentials without and with CP corrections. The effect of CP corrections on theE analysis is similar to that found in other systems of analogous composition (of the general type ion plus neutral ligands), but with significant differences in the details. The effect of the CP corrections to the interaction potential, and then on the results of the Monte Carlo simulations, is small for the Cu+ ion, but remarkable for the Cl– ion. 相似文献
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《Ceramurgia International》1977,3(1):10-12
The phase relationships at 1100°C among the reaction products of BaO, CaO and Fe2O3 were determined by the air quenching technique. Two binary solid solutions are formed, one between barium hexaferrite and a hypothetical calcium tetraferrite and another pseudobinary one adjacent to 2BaO·Fe2O3. Based on experimental results obtained by x-ray diffraction, optical microscopy and titrimetric determination of Fe+4, the 1100°C isothermal section for the system BaOCaOFe2O3 was derived. 相似文献
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