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1.
《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
2.
《Journal of the Less Common Metals》1991,167(2):373-379
Thermodynamic measurements by the electromotive force method were made on the binary intermetallic phases URu3 and U3Ru5 and on the ternary carbides URu3C0.7 and U2RuC2 of the URu and the URuC systems between 950 and 1200 K using galvanic cells with CaF2 single crystal electrolytes: U, UF3¦CaF2¦UF3, URu3, Ru; U, UF3¦CaF2¦UF3, U3Ru5, URu3; Ru, URu3, UF3¦CaF2¦UF3, URu3C0.7, Ru, C; U, UF3¦CaF2¦UF3, URu3C0.7, U2RuC2, C. The Gibbs energies of formation of URu3, U3Ru5, URu3C0.7 and U2RuC2 were evaluated from the measured electromotive force which give fΔGo〈URu3〉 = −199 100 + 35.9 T J mol−1fΔGo〈U3Ru5〉 = −398 600 + 43.6 T J mol−1fΔGo〈URu3C0.7〉 = −192 600 + 2.5 T J mol−1fΔGo〈U2RuC2〉 = −380 200 + 52.5 T J mol−1 The implications of these thermodynamic data for the behaviour of the fission product ruthenium in irradiated carbide fuels are discussed. 相似文献
3.
NdFeB and corresponding MmFeB compounds were studied, the high field magnetization at 4.2 K, the a.c. susceptibility (4.2 < T < 300 K) and the anisotropy field were measured using the singular point detection technique (77 < T < 570 K). At room temperature the anisotropy field of the MmFeB is about 3T, whereas that of NdFeB compounds is about 7T. The MmFeB compounds showed effects due to the cerium (lowering the Curie temperature) as well as due to the neodymium (spin reorientation at low temperatures). 相似文献
4.
《Journal of solid state chemistry》1987,69(1):186-188
ErBa2Cu3O7 and Er0.5Y0.5Ba2Cu3O7 are both high-Tc superconductors attaining zero resistance above 80 K. Preliminary studies indicate that Yb1−xYxBa2Cu3O7 also exhibits zero resistance above 77 K. 相似文献
5.
《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
6.
《Journal of solid state chemistry》1987,71(2):562-565
A hypothetical oxygen pressure-composition phase diagram and a projection of the oxygen pressure-temperature-composition diagram on the composition triangle were constructed from phase equilibria in the system MnCrO on the basis of the data available in literature. The temperature-composition phase equilibrium diagram of this same system in air was specified. Isomorphism of solid solutions with spinel and hausmannite structure and their intertransformation was studied. Two chemical compounds, MnCr2O4 and Cr4Mn28O48, are supposed to exist in the system. 相似文献
7.
The PtGaAs solid state equilibrium phase diagram was determined at 600 °C with the use of X-ray powder diffraction, electron probe microanalysis (EPMA) and scanning electron microscopy (SEM). No ternary PtGaAs phases were found and limited solid solubility was measured in the constituent binary PtGa and PtAs compounds. GaAs, PtGa and PtAs2 form a region of three-phase equilibrium which dominates the GaAs side of the phase diagram. The phase diagram is in agreement with previous observations that PtGa and PtAs2 are the stable phases when platinum thin films are reacted to completion on GaAs. 相似文献
8.
《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
9.
《Fluid Phase Equilibria》1988,39(1):101-110
Bubble-point pressures of the H2COCO2 system were measured at temperatures from 253.15 to 303.15 K and pressures up to 9 MPa. Multiple bubble-points were observed within certain limits of hydrogen compositions. The data have been compared with the calculated results by the Redlich-Kwong and the Peng-Robinson equations of state. 相似文献
10.
《Journal of Inorganic and Nuclear Chemistry》1979,41(12):1787-1792
The liquid-liquid extraction model for a binary metal system successfully applied to the lanthanide nitrate system was found to be applicable to the binary metal-mixed ligand system only when equal mole fractions of each metal components are present in the feed solution. The agreement in this special case is explained satisfactorily in terms of the two-suffix Margules equations. The lack of agreement between the chemically based model and the experimental data was attributed to the effects of the stability constants and the degree of formation of the lanthanide mixed ligand complexes on the separation factors. 相似文献
11.
《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
12.
13.
《Journal of the Less Common Metals》1987,127(1):147-153
The CeFe binary system was investigated and an FeCe binary phase diagram was proposed. This system consists of
- 1.(i) two peritectic reactions, γ-Fe + L → Ce2Fe17 and Ce2Fe17 + L → CeFe2, occurring isothermally at 1063°C and 925°C respectively;
- 2.(ii) a eutectic reaction, L → CeFe2 + Ce, occurring isothermally at 592°C with eutectic containing 83.3 at.% Ce (92.6 wt.% Ce);
- 3.(iii) a peritectoid reaction, γ-Fe + Ce2Fe17 → α-Fe(Ce), occurring isothermally at 922 °C.
14.
《Chemical physics letters》1985,119(4):317-319
Mercury helium and mercury xenon van der Waals complexes have been observed in a supersonic free jet expansion by laser-induced fluorescence in the vicinity of the Hg(3P11S0) transition. The helium complex very weakly bonded in the ground state (D0 = 8 ± 1 cm−1) exhibited a simple rotational structure. The strongly bonded xenon complex has shown a clear example of isotopic broadening in its vibronic spectra. 相似文献
15.
《Journal of the Less Common Metals》1989,146(1-2):213-219
The phase behavior of the AlIr system has been studied using differential thermal analysis, electron microprobe analysis, X-ray diffraction, chemical analysis and X-ray fluorescence. Our work confirms the existence of four compounds: Al9Ir2, Al3Ir, Al2.7Ir and AlIr. We also observed an additional intermetallic phase, with a stoichiometry corresponding to Al13Ir4; however, this compound exhibits a complex X-ray pattern and currently no structure has been determined.Peritectic temperatures were determined for Al9Ir2 (900 °C), Al13Ir4 (1015 °C) and Al3Ir (1450 °C). The Al2.7Ir phase is stable to above 1450 °C, and the congruent melting temperature of AlIr is 2120 ± 20 °C. The solubility of aluminum in iridium was measured between 1085 and 1850 °C, and the maximum solid solubility was extrapolated to 18 at.% at 2058 °C. The maximum solid solubility of iridium in aluminum was measured to be less than 0.1 at.%. A phase diagram for the AlIr system is presented. 相似文献
16.
17.
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
18.
《Solid State Sciences》2004,6(4):315-323
Starting from C3N4 and Si3N4 stoichiometries and from the pseudocubic model structure of the former, intermediate phases SiC2N4 and Si2CN4 are proposed and geometry optimised within density functional built pseudopotential method using both local density (LDA) and generalised gradient approximations (GGA). The ternary compounds are found to be less stable than the two binary systems but the trends in the calculated magnitudes of the bulk moduli B0 from the fit of the E(V) curves with Birch equation of state: B0 (SiC2N4)=334.5 GPa and B0 (Si2CN4)=270.3 GPa can be interpolated from those of the two extreme compounds: B0 (C3N4)=424.1 GPa and B0 (Si3N4)=219.8 GPa. This translates the chemical role of the substituting element on one hand and allows validating Cohen's semiempirical law relating B0 to the inverse powers of the average interatomic distances on the other hand. From a mismatch of the chemical bonding in Si(C)NC(Si) chain observed by the electron localisation function (ELF) plot we propose an interpretation for the instability of the intermediate ternary phases. The electronic structure (density of states and band structures) obtained from augmented spherical wave (ASW) calculations of the relaxed structures point to semiconducting behaviour with smaller band gaps for the intermediate phases (∼2 eV, compared with the ∼4 eV gap of binaries). 相似文献
19.
《Journal of the Less Common Metals》1979,63(2):P65-P74
The deflection technique developed originally for the study of the reversible diffusion-elastic phenomenon has been generalized for the study of eventual irreversible changes due to cathodic charging. The total deflection may be resolved in many cases into two components which are due to irreversible and reversible changes. It was found useful to regard the ratio of these two components as a criterion for the extent of permanent structural changes due to hydrogen charging. The method was applied to the system PtPdH. Metallographic studies were used to detect conspicuous irreversible changes on the surface of the samples. Increased hydrogen solubility in the system studied (attained, for example, by further alloying with Pd) reduces irreversible changes due to hydrogen charging. 相似文献