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1.
《Journal of the Less Common Metals》1987,127(1):183-191
The excess enthalpies of the liquid alloys GaGeTe and GaSnTe were measured in a heat-flow calorimeter at 1203 K. The enthalpy surface in the ternary space in both systems is characterized by a valley stretching from the exothermic minimum in the GaTe system to the minima of the GeTe and SnTe systems. The minima in the ternary systems were found in this valley, i.e. on the sections Ga2Te3-GeTe and Ga2Te3-SnTe. A comparison of the experimental data with those calculated from the excess enthalpies of the constituent binaries with the aid of the Bonnier model, reveals only small deviations. A preliminary investigation was made into the ternary phase diagram of GaSnTe. This system contains the two quasibinary sections Ga2Te3-SnTe, GaTe-SnTe and the ternary compound Ga6SnTe10. The previously reported compounds Ga2SnTe3 and GaSnTe2 do not exist. 相似文献
2.
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
3.
Using different calorimeters, the following measurements have been carried out.
- 1.(i) The integral enthalpies of mixing of CeCu binary and some CeMgCu ternary liquid alloys,
- 2.(ii) The enthalpy of formation and the enthalpy of melting of the intermetallic compound CeCu2.
- 3.(iii) The heat content of solid and liquid CeCu2.
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.
《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
6.
《Journal of solid state chemistry》1987,69(1):55-66
The AsGeTe system is formed by three independent triangles, corresponding to the two quasibinary systems GeAsGeTe and As2Te3GeTe. The presence of four phases As2GenTe3+n (n = 1 to 4) having peritectic decomposition introduces eight ternary peritectic invariants, whose temperatures and compositions are described. The three ternary eutectics have the following characters: E1, As19Ge52Te29 (662°C); E2, As42Ge5Te53 (368°C); E3, As22Ge5Te73 (350°C). 相似文献
7.
《Annales de Chimie Science des Materiaux》2002,27(3):99-109
The processing of metallic alloys through the procedure of equal-channel angular pressing (ECAP) provides an opportunity for achieving superplastic ductilities at very high strain rates. This paper reports experimental data from an investigation of a series of AlMgScZr alloys processed by ECAP. The results show the occurrence of high tensile ductilities at testing strain rates above 10−2 s−1. 相似文献
8.
《Annales de Chimie Science des Materiaux》2001,26(5):21-28
Transformation plasticity of a Fe18Mn8Cr5Ni5Si shape memory steel. This paper presents an experimental study of the transformation plasticity related to the γ→ε martensitic transformation in a Fe-18Mn-8Cr-5Ni-5Si shape memory steel. Under a weak bending stress the as-quenched austenitic samples showed a transformation plasticity by cooling at 170K with a plasticity coefficient h≈2. During heating, this transformation plasticity, related to the memory effect, is reversible, partially or completely, depending on whether the initial stress was maintained or removed at 295K during heating. 相似文献
9.
《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
10.
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
11.
《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
12.
《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
13.
《Solid State Sciences》2001,3(1-2):49-56
For application of LnSiON (Ln=Y, Gd and La) oxynitride materials, e.g. as host-lattices for lamp phosphors, oxidation resistance up to about 600 °C in air is a prerequisite. In this study we prepared LnSiON (Ln=Y, Gd and La) powders by solid state reaction and observed via TGA/DTA-experiments that most compounds are oxidation resistant up to 600 °C in air. The stability in air at high temperatures increases going from Ln5(SiO4)3N, Ln4Si2O7N2, LnSiO2N, Ln2Si3O3N4 to Ln3Si8O4N11. This is explained by an increasing cross-linking between the siliconoxygennitrogen tetrahedra in this sequence. For the lattices with less cross-linking between the siliconoxygennitrogen tetrahedra we observed that the oxidation resistance decreases slightly going from Y and Gd to La. For these lattices, also, an additional weight gain was observed during the oxidation reaction, which was higher than expected for complete oxidation. The additional weight gain was ascribed to an intermediate phase in which nitrogen retention takes place. 相似文献
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16.
《Journal of organometallic chemistry》1988,339(3):297-307
Trans-dicarbonylmethylnitrosyl-bis(triisopropylphosphite)tungsten (1) reacts with CO or CO2 to give (CO)2(ON)[P(O-i-Pr)3]2WCOCH3 (2) or (OC)(ON)[P(O-i-Pr)3]2W-η2-OOCCH3 (3), respectively.The hydride complex (OC)2(ON)[P(O-i-Pr)3]2WH (4a) undergoes insertion by CO2 or by activated acetylenes such as propiolic aldehyde or methyl propiolate to give (OC)2(ON)[P(O-i-Pr)3]2OC(O)H (5) or (OC)2(ON)]P(O-i-Pr)3]2CHCHR (R CHO, 6; R COOCH3, 7). 4a adds BH3 to yield a (OC)2(ON)[P(O-i-Pr)3]2WHBH3 system 8. This in turn can react with CO to give 4a and a (OC)3(ON)P(O-i-Pr)3WH complex (4b). 相似文献
17.
《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
18.
《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
19.
《Journal of organometallic chemistry》1988,346(1):C4-C6
Reaction-solution calorimetric studies involving the complexes Ti[η5-C5(CH3)5]2-(CH3)2, Ti[η5-C5(CH3)5]2(CH3), Ti[η5-C5(CH3)5]2(C6H5), Ti[η5-C5(CH3)5]2Cl2, and Ti[η5-C5(CH3)5]2Cl, have enabled derivation of titaniumcarbon and titaniumchlorine stepwise bond dissociation enthalpies in these species. 相似文献
20.
Nicolas DesroyRémi Le Roux Phannarath PhansavathLucia Chiummiento Carlo Bonini Jean-Pierre Genêt 《Tetrahedron letters》2003,44(9):1763-1766
The stereocontrolled synthesis of a C15C24 fragment of dolabelides is reported. The C19 and C21 hydroxyl-bearing stereocenters were installed using ruthenium-mediated asymmetric hydrogenations of cyclic hemiketal 4 and β-keto ester 7. The C25C30 portion of dolabelides was prepared as well by ring opening of chiral epoxy alcohol 12 to set up the C27 stereogenic center. 相似文献