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1.
The standard Gibbs free energies of formation of CuAlO2 and CuAl2 O4 were determined in the range 700° to 1100°C, using emf measurements on the galvanic cells (1) Pt,CuO +] Cu2 O/CaO-ZrO2 /O2 ,Pt; (2) Pt,Cu +] CuAlO2 +] Al2 O3 /CaO-ZrO2 / Cu +] Cu2 O,Pt; and (3) Pt,CuAl2 O4 +] CuAlO2 +]Al2 O3 /CaO-ZrO2 /O2 ,Pt. The results are compared with published information on the stability of these compounds. The entropy of transformation of CuO from tenorite to the rock-salt structure is evaluated from the present results and from earlier studies on the entropy of formation of spinels from oxides of the rock-salt and corundum structures. The temperatures corresponding to 3-phase equilibria in the system Cu2 O-CuO-Al2 O3 at specified O2 pressures calculated from the present results are discussed in reference to available phase diagrams. 相似文献
2.
Hyunjung Shin Monika Agarwal Mark R. De Guire Arthur H. Heuer 《Journal of the American Ceramic Society》1996,79(7):1975-1978
Thin films of crystalline TiO2 were deposited on self-assembled organic monolayers from aqueous TiCl4 solutions at 80°C; partially crystalline ZrO2 films were deposited on top of the TiO2 layers from Zr(SO4 )2 solutions at 70°C. In the absence of a ZrO2 film, the TiO2 films had the anatase structure and underwent grain coarsening on annealing at temperatures up to 800°C; in the absence of a TiO2 film, the ZrO2 films crystallized to the tetragonal polymorph at 500°C. However, the TiO2 and ZrO2 bilayers underwent solid-state diffusive amorphization at 500°C, and ZrTiO4 crystallization could be observed only at temperatures of 550°C or higher. This result implies that metastable amorphous ZrTiO4 is energetically favorable compared to two-phase mixtures of crystalline TiO2 and ZrO2 , but that crystallization of ZrTiO4 involves a high activation barrier. 相似文献
3.
Stephan Senz reas Graff Werner Blum Dietrich Hesse Hans-Peter Abicht 《Journal of the American Ceramic Society》1998,81(5):1317-1321
Fresnoite grows at 700° and 800°C, and Ba6 Ti7 O40 grows at 1200°C with definite orientations, which are determined by X-ray diffraction pole figure analysis. Partially textured fresnoite is formed at higher temperatures. The SiO2 films react with the BaTiO3 crystals, forming the phases Ba2 TiSi2 O8 (fresnoite) and Ba6 Ti17 O40 . At 700° and 800°C, both phases grow with definite orientations, which are determined by X-ray diffraction pole figure analysis. Partially textured polycrystalline phases are formed at higher temperatures. 相似文献
4.
Kirk A. Rogers Kevin P. Trumble Brian J. Dalgleish Ivar E. Reimanis 《Journal of the American Ceramic Society》1994,77(8):2036-2042
Microstructure development at solid-state diffusion-bonded Cu/α-Al2 O3 interfaces has been studied using optical and electron microscopy. High-purity Cu foil was bonded between basal-oriented α-Al2 O3 single-crystal plates at 1040°C for 24 h in a vacuum of ∼1.3 × 10−4 Pa (1 × 10−6 torr). Optical microscopy of as-bonded specimens revealed a large Cu grain size, fine pores, and long needles of Cu2 O at the interface. Bulk specimens were annealed at 1000°C for various times under controlled oxygen partial pressures in CO/CO2 mixtures. Consistent with a thermochemical analysis, CuAlO2 could be formed at the interfaces. The CuAlO2 was acicular and discontinuous, but occurred in a uniform distribution over the bulk specimen interfaces. 相似文献
5.
Kevin P. Trumble 《Journal of the American Ceramic Society》1999,82(10):2919-2920
A pseudobinary thermodynamic analysis of the alumina/copper–oxygen eutectic bonding process yields a value of approximately 1076°C for the invariant temperature of the {Cu( ss ), Cu( L1 ), CuAlO2 , Al2 O3 } equilibrium. This temperature, which is 11°C above the eutectic, corresponds to a critical temperature for stability of the copper aluminate CuAlO2 in eutectic bonding. Implications for controlling interface microstructure are highlighted. 相似文献
6.
Alessandro Martucci Sabrina Sartori Alessandro Muffato Lidia Armelao Elisabetta Di Bartolomeo Enrico Traversa Massimo Guglielmi 《Journal of the American Ceramic Society》2003,86(11):1965-1968
Na2 O· x Al2 O3 ( x = 9, 11)films have been obtained by sol–gel method. Crystallization processes during heat treatments have been investigated by X–ray diffraction analysis. A metastable phase with the mullite structure, λ–Na2 O· x Al2 O3 , has been observed starting from 800°C. Films remained stable after a heat treatment at 1000°C for 250 h. Impedance spectroscopy measurements showed that the films of λ-Na2 O· x Al2 O3 possess a large three–dimensional ionic conductivity at 400°C. 相似文献
7.
Toshinobu Yogo Wataru Sakamoto Tadayuki Isaji Koichi Kikuta Shin-ichi Hirano 《Journal of the American Ceramic Society》1997,80(7):1767-1772
Transparent and highly oriented Ba2 NaNb5 O15 (BNN) thin films have been prepared by using metal alkoxides. A homogeneous precursor solution was prepared by the controlled reaction of NaOC2 H5 , Nb(OC2 H5 )5 , and barium metal. The BNN precursor included a molecular-level mixture of NaNb(OC2 H5 )6 and Ba[Nb(OC2 H5 )6 ]2 in ethanol. The alkoxy-derived powder crystallized to a low-temperature phase, and then transformed to orthorhombic BNN (tungsten bronze) at 600°C. BNN precursor films on substrates crystallized to orthorhombic BNN at 800°C via the low-temperature phase. Highly (002) oriented BNN films of tungsten bronze structure were successfully prepared on MgO (100) substrates at 700°C by using BNN underlayer. 相似文献
8.
J. J. COMER N. C. TOMBS J. F. FITZGERALD 《Journal of the American Ceramic Society》1966,49(5):237-240
Single-crystal and polycrystalline films of Mg-Al2 O4 and MgFe2 O4 were formed by two methods on cleavage surfaces of MgO single crystals. In one procedure, aluminum was deposited on MgO by vacuum evaporation. Subsequent heating in air at about 510°C formed a polycrystalline γ-Al2 O8 film. Above 540°C, the γ-Al2 O, and MgO reacted to form a single-crystal MgAl2 O4 film with {001} MgAl2 O4 ‖{001} MgO. Above 590°C, an additional layer of MgAl2 O4 , which is polycrystalline, formed between the γ-Al2 O3 and the single-crystal spinel. Polycrystalline Mg-Al2 O4 formed only when diffusion of Mg2+ ions proceeded into the polycrystalline γ-Al2 O3 region. Corresponding results were obtained for Mg-Fe2 O4 . MgAl2 O4 films were also formed on cleaved MgO single-crystal substrates by direct evaporation, using an Al2 O3 crucible as a source. Very slow deposition rates were used with source temperatures of ∼1350°C and substrate temperatures of ∼800°C. Departures from single-crystal character in the films may arise through temperature gradients in the substrate. 相似文献
9.
Shin-ichi Hirano Takashi Hayashi Masashi Miura 《Journal of the American Ceramic Society》1990,73(4):885-888
Superconducting Ba2 YCu3 O7-δ thin films were prepared through an organometallic route. Single-phase Ba2 YCu3 O7-δ thin films with preferred orientation were successfully prepared on SrTiO3 (100) single-crystal substrates at 800°C by a dip coating method using partially hydrolyzed Ba-Y-Cu organometallic solutions. Preferentially oriented Ba2 YCu3 -O7-δ thin films were also prepared on MgO (100) substrates. By controlling the partial hydrolysis conditions, a coating solution for precursor thin films was kept accurately at the stoichiometric composition. The use of ozone gas during the pyrolysis of the precursor thin films was found to suppress the formation of BaCO3 . Ba2 YCu3 O7-δ thin films with c -axis orientation perpendicular to a SrTiO3 (100) substrate, which were heat-treated at 900°C for 15 min, exhibited a superconductivity transition with an onset of 90 K and an end of 75 K. 相似文献
10.
A TiN precursor solution was synthesized by galvanostatic electrolysis of Ti metal and isopropylamine at a current density of 50 mA·cm−2 at room temperature. TiN films were prepared by dip-coating of the precursor solution on a Si wafer, followed by two-stage heat treatment at 400°C and a fixed temperature of 800–1200°C in flowing N2 , N2 /NH3 , or NH3 gas. The TiN films were characterized by XRD, chemical analysis, XPS, and electrical resistivity measurements. The TiN films were composed of uniform grains 20 to 200 nm in size with thicknesses ranging from 300 to 400 nm at temperatures of 800–1200°C. The effect of the heat treatment atmosphere (N2 and NH3 ) on the impurity content, crystallinity, particle size, and electrical resistivity is discussed. 相似文献
11.
Pb(Mg1/3 Nb2/3 )O3 –PbTiO3 (PMN–PT) thin films were prepared by spin coating using aqueous solutions of metal salts containing polyvinylpyrrolidone, where niobium oxide layers and lead—magnesium–titanium oxide layers were laminated on Pt(111)/TiO x /SiO2 /Si(100) substrates and fired at 750° or 800°C. 250 ± 20 nm thick 0.7PMN–0.3PT thin films of a single-phase perovskite could be prepared, and the film fired at 750°C had dielectric constants and dielectric loss of 1900 ± 350 and 0.13 ± 0.03, respectively, exhibiting polarization-electric field hysteresis with a remanent polarization of 5.1 μC/cm2 and a coercive field of 21 kV/cm. 相似文献
12.
Yaohui Zhang Xiqiang Huang Zhe Lu Zhiguo Liu Xiaodong Ge Jiahuan Xu Xianshuang Xin Xueqing Sha Wenhui Su 《Journal of the American Ceramic Society》2006,89(7):2304-2307
Gas-tight Y2 O3 -stabilized ZrO2 (YSZ) films were prepared on NiO–YSZ and NiO–SDC (Sm0.2 Ce0.8 O1.9 ) anode substrates by a novel method. A cell, Ni–YSZ/YSZ(10 μm)/LSM–YSZ, was tested with humidified hydrogen as fuel and ambient air as oxidant. The maximum power densities of 1.64, 1.40, 1.06, and 0.60 W/cm2 were obtained at 850°, 800°, 750°, and 700°C, respectively. With methane as fuel, a cell of Ni–SDC/YSZ (12 μm)/LSM–YSZ exhibited the maximum power densities of 1.14, 0.82, 0.49, and 0.28 W/cm2 at 850°, 800°, 750°, and 700°C, respectively. The impedance results showed that the performance of the cell was controlled by the electrode polarization rather than the resistance of YSZ electrolyte film. 相似文献
13.
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
14.
Monika Agarwal Mark R. de Guire Arthur H. Heuer 《Journal of the American Ceramic Society》1997,80(12):2967-2981
Undoped or Y2 O3 -doped ZrO2 thin films were deposited on self-assembled monolayers (SAMs) with either sulfonate or methyl terminal functionalities on single-crystal silicon substrates. The undoped films were formed by enhanced hydrolysis of zirconium sulfate (Zr(SO4 )·4H4 O) solutions in the presence of HCl at 70°C. Typically, these films were a mixture of two phases: nanocrystalline tetragonal- ( t -) ZrO2 and an amorphous basic zirconium sulfate. However, films with little or no amorphous material could be produced. The mechanism of film formation and the growth kinetics have been explained through a coagulation model involving homogeneous nucleation, particle adhesion, and aggregation onto the substrate. Annealing of these films at 500°C led to complete crystallization to t -ZrO2 . Amorphous Y2 O3 -containing ZrO2 films were prepared from a precursor solution containing zirconium sulfate, yttrium sulfate (Y2 (SO4 )3 8·H2 O), and urea (NH2 CONH2 ) at pH 2.2–3.0 at 80°C. These films also were fully crystalline after annealing at 500°C. 相似文献
15.
Polymeric cyanoborane, (CNBH2 ) n , is a material readily prepared by passing hydrogen chloride through an ether suspension of sodium cyanotrihydroborate. This polymeric material was volatilized in a CVD reactor to produce, at 600°C, amorphous films containing boron, nitrogen, and carbon. Residual carbon present in the films was removed by ammonia treatment at 800°C, producing nearly stoichiometric boron nitride films that were adherent to a variety of substrates including silicon. 相似文献
16.
Enrico Traversa Stefano Villanti Gualtiero Gusmano Hiromichi Aono Yoshihiko Sadaoka 《Journal of the American Ceramic Society》1999,82(9):2442-2450
Ultrafine SmFeO3 powders were prepared by the thermal decomposition at 700°C of the corresponding hexacyanocomplex, Sm[Fe(CN)6 ]·4H2 O. These powders were used for the preparation of pastes which were deposited as thick films on alumina substrates with comb-type Au electrodes. The films were fired at different temperatures in the 800-1000°C range. The content of α-terpineol, a component of the organic vehicle, was varied in the range 0.0046-4 wt%. The microstructure, the chemical composition at the surface, the electrical conductivity, and the NO2 sensing properties of the films were investigated. The content of α-terpineol strongly influenced the electrical conductivity and its activation energy. A significant reduction in the NO2 response was observed for the films containing smaller amounts of α-terpineol, together with an increase in conductivity. On the other hand, the largest NO2 response was observed for the films fired at 1000°C when 4 wt% of α-terpineol was used. Such increase in conductivity is attributed to a different oxygen surface layer on the SmFeO3 surface, which is induced by the decomposition reaction of α-terpineol during sintering. The materials processing parameters are thus of primary concern for the NO2 sensing properties of the SmFeO3 thick films. The correlations found between activation energy, NO2 sensitivity, and materials characteristics (influenced by the preparation parameters) are reported. These correlations can be used to design the gas-sensing properties of SmFeO3 thick films for the optimization of their sensing characteristics. 相似文献
17.
Bo-Yun Jang Young-Hun Jeong Suk-Jin Lee Kyong-Jae Lee Sahn Nahm Ho-Jung Sun Hwack-Joo Lee 《Journal of the American Ceramic Society》2005,88(5):1209-1212
BaTi4 O9 thin films were grown on a Pt/Ti/SiO2 /Si substrate using rf magnetron sputtering and the structure of the thin films were then investigated. For the films grown at low temperature (≤350°C), an amorphous phase was formed during the deposition, which then changed to the BaTi5 O11 phase when the annealing was conducted below 950°C. However, when the annealing temperature was higher than 950°C, a BaTi4 O9 phase was formed. On the contrary, for the films grown at high temperature (>450°C), small BaTi4 O9 grains were formed during the deposition, which grew during the annealing. The homogeneous BaTi4 O9 thin films were successfully grown on Pt/Ti/SiO2 /Si substrate when they were deposited at 550°C and subsequently rapid thermal annealed at 900°C for 3 min. 相似文献
18.
Mi-Ri Joung Jin-Seong Kim Myung-Eun Song Jae-Hong Choi Jong-Woo Sun Sahn Nahm Jong-Hoo Paik Byung-Hyun Choi 《Journal of the American Ceramic Society》2009,92(9):2151-2154
Li2 CO3 was added to Mg2 V2 O7 ceramics in order to reduce the sintering temperature to below 900°C. At temperatures below 900°C, a liquid phase was formed during sintering, which assisted the densification of the specimens. The addition of Li2 CO3 changed the crystal structure of Mg2 V2 O7 ceramics from triclinic to monoclinic. The 6.0 mol% Li2 CO3 -added Mg2 V2 O7 ceramic was well sintered at 800°C with a high density and good microwave dielectric properties of ɛ r =8.2, Q × f =70 621 GHz, and τf =−35.2 ppm/°C. Silver did not react with the 6.0 mol% Li2 CO3 -added Mg2 V2 O7 ceramic at 800°C. Therefore, this ceramic is a good candidate material in low-temperature co-fired ceramic multilayer devices. 相似文献
19.
Matthias Diemer Achim Neubrand Kevin P. Trumble Jürgen Rödel 《Journal of the American Ceramic Society》1999,82(10):2825-2832
The influence of oxygen on the wetting behavior of copper on single-crystal Al2 O3 has been studied. By controlling the oxygen partial pressure ( p O2 ) and oxygen content in the copper simultaneously, contact angle can be varied between 125° and 22°. Evaluation of the Gibbs adsorption equation for the liquid/solid interface at 1300°C suggests that adsorption of a Cu-O complex at that interface plays a key role in promoting wetting. Formation of CuAlO2 and dissolution of Al2 O3 in the melt also influence the contact angle, especially in the range of p O2 > 10−5 bar (1 Pa). 相似文献
20.
A solution-derived precursor may be calcined at temperatures >500°C to yield MgNb2 O6 . Calcining temperatures 800°C result in the familiar, cation-ordered columbite structure type. Calcining temperatures <800°C result in a previously unobserved, cation-disordered α-PbO2 structure type. The low-temperature form of MgNb2 O6 is a more reactive material than is obtained by conventional solid-state reaction as evidenced by its small particle size and its ability to react with PbO to form lead magnesium niobate at lower temperatures. 相似文献