共查询到20条相似文献,搜索用时 15 毫秒
1.
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
2.
Do-Kyun Kwon Teppei Akiyoshi Hyeongjae Lee Michael T. Lanagan 《Journal of the American Ceramic Society》2008,91(3):906-909
Manganese dioxide (α-MnO2 ) thin films have been explored as a cathode material for reliable glass capacitors. Conducting α-MnO2 thin films were deposited on a borosilicate glass substrate by a chemical solution deposition technique. High carbon activities originated from manganese acetate precursor, (Mn(C2 H3 O2 )2 ·4H2 O) and acetic acid solvent (C2 H4 O2 ), which substantially reduced MnO2 phase stability, and resulted in Mn2 O3 formation at pyrolysis temperature in air. The α-MnO2 structure was stabilized by Ba2+ insertion into a (2 × 2) oxygen tunnel frame to form a hollandite structure. With 15–20 mol% Ba addition, a conducting α-MnO2 thin film was obtained after annealing at 600–650°C, exhibiting low electrical resistivity (∼1 Ω·cm), which enables application as a cathode material for capacitors. The hollandite α-MnO2 phase was stable at 850°C, and thermally reduced to the insulating bixbyte (Mn2 O3 ) phase after annealing at 900°C. The phase transition temperature of Ba containing α-MnO2 was substantially higher than the reported transition temperature for pure MnO2 (∼500°C). 相似文献
3.
Jungho Ryu Kun-Young Kim Jong-Jin Choi Byung-Dong Hahn Woon-Ha Yoon Byoung-Kuk Lee Dong-Soo Park Dae-Yong Jeong Chan Park 《Journal of the American Ceramic Society》2009,92(2):524-527
Flexible thin films of Bi1.5 Zn1.0 Nb1.5 O7 (BZN) were deposited on a Cu/polyimide (PI) foil by aerosol deposition at room temperature. The BZN film thickness was in the range of 1.2–17.9 μm. Highly dense and nanocrystalline films were obtained without any heat treatment. The dielectric constant and loss of the film at 100 kHz were over 150 and 0.04, respectively. Furthermore, the as-deposited film showed markedly low leakage current densities of <10−9 A/cm2 at 3.0 V. These reasonably high dielectric properties were due to the nanocrystallinity of the films. The results confirm the significant potential of the BZN films as passive components in flexible printed circuit board applications. 相似文献
4.
Joanna McKittrick Carlos F. Bacalski G. A. Hirata Kevin M. Hubbard S. G. Pattillo Kenneth V. Salazar M. Trkula 《Journal of the American Ceramic Society》2000,83(5):1241-1246
The purpose of this study was to identify and correlate the microstructural and luminescence properties of europium-doped Y2 O3 (Y1– x Eu x )2 O3 thin films deposited by metallorganic chemical vapor deposition (MOCVD), as a function of deposition time and temperature. The influence of deposition parameters on the crystallite size and microstructural morphology were examined, as well as the influence of these parameters on the photoluminescence emission spectra. (Y1– x Eu x )2 O3 thin films were deposited onto (111) silicon and (001) sapphire substrates by MOCVD. The films were grown by reacting yttrium and europium tris(2,2,6,6-tetramethyl–3,5-heptanedionate) precursors with an oxygen atmosphere at low pressures (5 torr (1.7 × 103 Pa)) and low substrate temperatures (500°–700°C). The films deposited at 500°C were smooth and composed of nanocrystalline regions of cubic Y2 O3 , grown in a textured [100] or [110] orientation to the substrate surface. Films deposited at 600°C developed, with increasing deposition time, from a flat, nanocrystalline morphology into a platelike growth morphology with [111] orientation. Monoclinic (Y1– x Eu x )2 O3 was observed in the photoluminescence emission spectra for all deposition temperatures. The increase in photoluminescence emission intensity with increasing postdeposition annealing temperature was attributed to the surface/grain boundary area-reduction effect. 相似文献
5.
A novel and cost-effective electrostatic spray-assisted vapor deposition (ESAVD) was used to deposit Y3 Al5 O12 (YAG) coatings. Polycrystalline single-phase Y3 Al5 O12 coatings were synthesized using the ESAVD method in an open atmosphere at 650°C, and then annealed at 700°–900°C for 1 h. The ESAVD process involves the decomposition and chemical reactions of charged aerosol in vapor phase. The low-temperature coating deposition characteristics of the ESAVD process using a suitable sol precursor decreases the reaction and crystallization temperatures for forming Y3 Al5 O12 coatings. The microstructure of the Y3 Al5 O12 coating prepared using the ESAVD method is columnar and such strain-resistance microstructure could be useful for thermal barrier coating applications. 相似文献
6.
Continuous α-Fe2 O3 films grown on bulk (0001)Al2 O2 substrates by low-pressure chemical vapor deposition have been studied by transmission electron microscopy and the observations compared to those obtained from discontinuous films at an earlier stage of the growth process. Plan-view specimens revealed significant thermal stress in the continuous films, while cross-sectional specimens showed that cracking occurs in thicker films. The free surface of the film and the film/substrate interface appeared sharp and flat, apart from growth ledges and steps. Weak-beam imaging revealed a hexagonal misfit dislocation network consisting of perfect edge dislocations. Fine structure in the selected-area diffraction patterns which corroborates these observations is also discussed. The misfit network of partial dislocations previously observed in the discontinuous films was not observed for the continuous films, indicating an effect of film thickness, growth rate, or surface preparation on the Fe2 O3 /(0001)Al2 O3 interface structure. 相似文献
7.
Andrey V. Zagrebelny Erica T. Lilleodden William W. Gerberich C. Barry Carter 《Journal of the American Ceramic Society》1999,82(7):1803-1808
The deformation of thin layers of glass on crystalline materials has been examined using newly developed experimental methods for nanomechanical testing. Continuous films of anorthite (CaAl2 Si2 O8 ) were deposited onto Al2 O3 surfaces by pulsed-laser deposition. Mechanical properties such as Young's modulus and hardness were probed with a high-resolution depth-sensing indentation instrument. Nanomechanical testing, combined with AFM in situ imaging of the deformed regions, allowed force-displacement measurements and imaging of the same regions of the specimen before and immediately after indentation. This new technique eliminates any uncertainty in locating the indentation after unloading. Emphasis has been placed on examining how the Al2 O3 substrate crystallographic orientation will affect mechanical composite response of silicate-glass film/Al2 O3 system. 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.
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
10.
Pb(Mg1/3 Ta2/3 )0.7 Ti0.3 O3 thin films of single perovskite phase were successfully synthesized by using the RF sputtering deposition technique, followed by post-thermal annealing. While the perovskite structure of Pb(Mg1/3 Ta2/3 )0.7 Ti0.3 O3 is rather unstable, phase evolution in the thin films was manipulated by controlling both working pressure during the sputtering process and post-thermal annealing temperature. The desirable perovskite phase was promoted by increasing the working pressure in the range of 10–25 mTorr, followed by thermal annealing at 600°C. The ferroelectric, dielectric, and polarization behaviors of Pb(Mg1/3 Ta2/3 )0.7 Ti0.3 O3 films were characterized over a wide range of frequencies. They are strongly affected by the film thickness, where the relative permittivity and remanent polarization increase, while the coercive field decreases with increasing film thickness in the range of 115–360 nm. 相似文献
11.
H. Sieger J. Suffner H. Hahn A.R. Raju G. Miehe 《Journal of the American Ceramic Society》2006,89(3):979-984
Nanocrystalline Sm2 O3 and Sm2 O3 –MgO powders have been prepared by spray pyrolysis of aqueous precursor solutions containing citric acid as a complexant. Synthesized powders consist of hollow spheres with thin shells. The two-phase samples exhibit an improved microstructural stability compared with pure Sm2 O3 . The microstructure before and after various heat treatments has been investigated by high-resolution transmission electron microscopy, scanning electron microscopy, nitrogen adsorption, and X-ray diffraction. 相似文献
12.
Polycrystalline Al2 O3 was chemically vapor-deposited onto sintered Al2 O3 substrates by reaction of AlCl3 with (1) H2 O, (2) CO:H2 , and (3) O2 at 1000° and 1500°C and 0.5 and 5.0 torr. Although the thermodynamics of all these reactions predict the formation of solid Al2 O3 , the deposition rate of the first reaction was considerably greater than that of the second. The third reaction was so slow that no measurable deposit was formed in 6 h at 1500°C. Formation of dense deposits of α-Al2 O3 was favored by increasing temperature and decreasing pressure. Microstructural examination of the dense deposits showed long columnar grains, the largest of which extended through the deposit from the substrate to the surface. 相似文献
13.
Nicolas Nadaud Monique Nanot Philippe Boch 《Journal of the American Ceramic Society》1994,77(3):843-846
The deposition rate and film quality of In2 O3 -SnO2 (ITO) transparent electrodes processed by sputtering are improved when using dense sputtering targets. Unfortunately, ITO ceramics do not sinter easily. It is shown that addition of TiO2 (<1 wt%) to ITO greatly increases densification without degrading electrical properties of sputtered films. The influence of ZrO2 and SiO2 was also investigated. 相似文献
14.
Yoshihito Mizoguchi Masahiro Kagawa Yasuhiko Syono Toshio Hirai 《Journal of the American Ceramic Society》2001,84(3):651-653
Thin films of yttrium aluminum garnet (YAG, Y3 Al5 O12 ) and yttrium iron garnet (YIG, Y3 Fe5 O12 ) were synthesized on single-crystal Al2 O3 substrates by a modification of spray pyrolysis using a high-temperature inductively coupled plasma at atmospheric pressure (spray–ICP technique). Using this technique, films could be grown at faster rates (0.12 μm/min for YAG and 0.10 μm/min for YIG) than using chemical vapor deposition (0.005–0.008 μm/min for YAG) or sputtering (0.003–0.005 μm/min for YIG). The films were dense and revealed a preferred orientation of (211). The growth of YIG was accompanied by coprecipitation of α-Fe2 O3 . The coprecipitation, however, could be largely suppressed by preliminary formation of a Y2 O3 layer on the substrate. 相似文献
15.
Hae Jin Hwang Jooho Moon Masanobu Awano Kunihiko Maeda 《Journal of the American Ceramic Society》2000,83(11):2852-2854
Sol–gel-derived LaCoO3 thin films were deposited on yttria-stabilized zirconia (YSZ) substrates from a lanthanum isopropoxide–cobalt acetate (with 2-methoxyethanol) precursor solution. A chelating agent (2-ethylacetoacetate) and polyethylene glycol (PEG) were used to modify the above-mentioned precursor solution. The La-Co precursor solution was sufficiently viscous, and transparent LaCoO3 gel films were prepared successfully using a spin-coating technique. Crystallization behavior and microstructure evolution were investigated using X-ray diffractometry (XRD) and scanning electron microscopy (SEM). A single-phase perovskite thin film with the grain size of ∼50 nm was obtained by heat-treating the spin-coated gel film at a temperature of 600°C. SEM observations revealed that the microstructure of LaCoO3 thin films that were prepared from the precursor solution with PEG was porous, and the LaCoO3 thin film maintained its porous microstructure to a temperature of 800°C. 相似文献
16.
Robert W. Schwartz Paul G. Clem James A. Voigt Elena R. Byhoff Melanie Van Stry Thomas J. Headley Nancy A. Missert 《Journal of the American Ceramic Society》1999,82(9):2359-2367
Columnar and highly oriented (100) BaTiO3 and SrTiO3 thin films were prepared by a chelate-type chemical solution deposition (CSD) process by manipulation of film deposition conditions and seeded growth techniques. Randomly oriented columnar films were prepared on platinum-coated Si substrates by a multilayering process in which nucleation of the perovskite phase was restricted to the substrate or underlying layers by control of layer thickness. The columnar films displayed improvements in dielectric constant and dielectric loss compared to the fine-grain equiaxed films that typically result from CSD methods. Highly oriented BaTiO3 and SrTiO3 thin films were fabricated on LaAlO3 by a seeded growth process that appeared to follow a standard "two-step" growth mechanism that has been previously reported. The film transformation process involved the bulk nucleation of BaTiO3 throughout the film, followed by the consumption of this matrix by an epitaxial overgrowth process originating at the seed layer. Both BaTiO3 and PbTiO3 seed layers were effective in promoting the growth of highly oriented (100) BaTiO3 films. Based on the various processing factors that can influence thin film microstructure, the decomposition pathway involving the formation of BaCO3 and TiO2 appeared to dictate thin film microstructural evolution. 相似文献
17.
Robert J. Sullivan Thallam T. Srinivasan Robert E. Newnham 《Journal of the American Ceramic Society》1990,73(12):3715-3717
The evaporative decomposition of solutions method was used to form V2 O5 . Spraying above the congruent melting temperature of V2 O5 (690°C) resulted in dense spherical particles with a smooth surface. Spraying below the V2 O5 melting temperature yielded porous V2 O5 powder with a rough surface. Reduction of the V2 O5 to V2 O3 was done in a H2 atmosphere. Spherical V2 O3 powder was attained when the reduction temperature was low enough to reduce the V2 O5 surface before partial sintering (necking) between V2 O5 particles occurred. The resulting V2 O3 particle size was smaller than the precursor V2 O5 powder as expected by the differences in densities between V2 O5 ( p = 3.36 g/cm3 ) and V2 O3 ( p = 4.87 g/cm3 ). 相似文献
18.
Tadasu Hosokura Keisuke Kageyama Hiroshi Takagi Yukio Sakabe 《Journal of the American Ceramic Society》2009,92(1):253-255
Epitaxially grown single-crystal perovskite (100) three-axis-oriented (Ba0.7 Sr0.3 )TiO3 thin films were prepared on a (100) platinum-coated (100) magnesium oxide (MgO) single-crystal substrate by the chemical solution deposition method using a solution derived from Ba(CH3 COO)2 , Sr(CH3 COO)2 , and Ti(O- i -C3 H7 )4 .
The growth of the film was found to depend on the annealing condition. A (Ba,Sr)TiO3 thin film annealed at 1073 K was found to be a single crystal by transmission electron microscope. The single-crystal film exhibited a (100) three-axis orientation that followed the (100) orientation of the Pt substrate, as observed from an X-ray pole figure measurement and selected area electron diffraction patterns. 相似文献
The growth of the film was found to depend on the annealing condition. A (Ba,Sr)TiO
19.
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
20.
Rabindra N. Das Amit Bandyopadhyay Susmita Bose 《Journal of the American Ceramic Society》2001,84(10):2421-2423
Nanocrystalline α-Al2 O3 ceramic powders have been prepared from an aqueous solution of aluminum nitrate and sucrose. Soluble Al ion-sucrose solution forms the precursor material once it is completely dehydrated. Heat treatment of the dehydrated precursors at low temperature (600°C) results in the formation of porous single-phase α-Al2 O3 . The precursor and heat-treated powders have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and BET surface area analysis. The phase-pure nanocrystalline α-Al2 O3 particles had an average specific surface area of >190 m2 /g, with an average pore size between 18 and 25 nm. 相似文献