共查询到20条相似文献,搜索用时 156 毫秒
1.
Jean C. Pivin Paolo Colombo Gian D. Sorarù 《Journal of the American Ceramic Society》2000,83(4):713-720
Thin films of polymers (polysiloxanes, polycarbosilanes, and polysilazanes) and alkoxide-derived siloxane gels, precursors for SiC, SiCN, SiOC, and SiOBC ceramics, were irradiated with increasing fluences of C or Au ions to study the kinetics of their conversion into ceramics. Ion beam analyses showed that the main effect of irradiation on the composition of the films is the selective release of H2 by radiolysis. During subsequent high-temperature annealing of films converted as much as possible by irradiation, CO x , CH x , or silane molecules do not evolve, contrary to what is observed during the pyrolysis of unirradiated precursor films. According to Raman analyses, a large proportion of the carbon atoms segregate into clusters after irradiation and in films converted by direct pyrolysis (or combined treatments). However, carbon particles formed during irradiation are more diamond-like, affording films with 2—3 times higher hardness, as shown by nanoindentation tests. In both types of ceramics (SiC or SiOC), the optimal properties (hardness, thermal stability, and photoluminescence) associated with C segregation are obtained for a C/Si ratio of the order of 1. Boron addition is detrimental to hardening of SiOC glasses, in contrast to nitrogen. 相似文献
2.
Masayuki Fujimoto Hiroshi Koyama Yuji Nishi Toshimasa Suzuki Shinji Kobayashi Yukio Tamai Nobuyoshi Awaya 《Journal of the American Ceramic Society》2007,90(7):2205-2209
We characterized the structure of the crystallographic domain of a (Pr0.7 Ca0.3 )MnO3 (PCMO ( x =0.3)) thin film epitaxially grown on a (001)SrTiO3 (STO) single-crystal substrate. We found that the domain structure exhibited an atomically smooth coherent interface with the STO substrate with no misfit dislocations. The crystallographic relationships between the domains and the substrate in their planes were interpreted to be PCMO ( x =0.3)[110][001]//STO[100][010] and PCMO ( x =0.3)[001][1-10]//STO[100][010]. The domain structure of PCMO ( x =0.3)[110][1-10]//STO[100][010] has less possibility of having the larger anisotropic strain energy found in a monoclinically distorted pseudo-cubic perovskite unit cell of PCMO ( x =0.3). This epitaxial growth structure is totally different from the previously reported PCMO ( x =0.5) epitaxial thin-film structure on STO substrate. Our observations suggested that an x value change strongly influences the structure of epitaxial PCMO thin films. 相似文献
3.
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
4.
Fine Patterning and Characterization of Gel Films Derived from Methyltriethoxysilane and Tetraethoxysilane 总被引:1,自引:0,他引:1
Atsunori Matsuda Yoshihiro Matsuno Masahiro Tatsumisago Tsutomu Minami 《Journal of the American Ceramic Society》1998,81(11):2849-2852
Pregrooves of 1.6 µm pitch for optical data storage have been embossed successfully by pressing a stamper against x CH3 Si(OC2 H5 )3 (100 - x )Si(OC2 H5 )4 -derived gel films (60 ≤ x ≤ 100 mol%) on glass-disk substrates of 130 mm diameter. When x is <40 mol%, the resultant films are too hard to emboss patterns uniformly. The shrinkage of the patterns is ∼4% for all the films when 60 lessthan equal to x lessthan equal to 100 mol%, even after heat treatment at 350°C, so that the nearly net negative shape of the stamper is preserved. The methyl groups in the films decompose at temperatures from 500° to 600°C. 相似文献
5.
Jeong Hwan Park Ki Hyun Yoon Dong Heon Kang 《Journal of the American Ceramic Society》1999,82(10):2683-2688
Physical and dielectric properties of (1– x )PbZrO3 · x BaTiO3 thin films prepared by a chemical coating process have been investigated as a function of BaTiO3 ( x ) content (0≤ x ≤0.2). Changing the molar ratio between propylene glycol and water prior to the deposition optimized the chemical precursors. (1– x )PbZrO3 - x BaTiO3 thin films that contained a majority of perovskite phase, but also contained large amounts of other phases, were fabricated. These films could withstand fields of 250 kV/cm at 1 kHz. The microstructure of the thin films was found to depend on the BaTiO3 content. The phase transition from antiferroelectric to ferroelectric was gradually induced as the BaTiO3 content increased. A maximum dielectric constant of ∼809 was obtained at the composition of x = 0.1. A maximum dielectric constant of ∼809 was obtained at the composition of x = 0.1. A thin film at the low-field antiferroelectric-ferroelectric phase boundary with x = 0.05 exhibited the highest P sat and P r values. The maximum values of these were 45 and 31 μC/cm2 , respectively. 相似文献
6.
Wen-Jen Lin Tseung-Yuen Tseng Sheuan-Perng Lin Shun-Lih Tu Hong Chang Sheng-Jenn Yang I-Nan Lin 《Journal of the American Ceramic Society》1997,80(5):1065-1072
Lead lanthanum zirconate titanate (Pb1− x La x (Zr y ,Ti z )O3 , PLZT) films containing [00 l ] preferentially oriented grains were produced successfully on YBa2 Cu3 O7− x -coated (YBCOcoated) SrTiO3 (STO) or YBCO/CeO2 -coated silicon substrates; films containing randomly oriented grains were created on platinum-coated silicon substrates. The latter possessed significantly inferior ferroelectric properties, a fact ascribed to the presence of a paraelectric phase (TiO2 ) at the PLZT/platinum interface. On the other hand, the PLZT/YBCO/STO films exhibited better electrical properties than did the PLZT/YBCO/CeO2 /Si films, and this phenomenon was attributed to better alignment of the grains in normal and in-plane orientations. In terms of fatigue properties, the [00l] textured films that were deposited on YBCO/CeO2 /Si substrates possessed substantially superior polarization-switching-cycle endurance versus the randomly oriented films grown on Pt(Ti)/Si substrates. Moreover, the tetragonal films behaved much more satisfactorily than did the rhombohedral PLZT films. The ferroelectric parameters of tetragonal PLZT films showed no significant degradation up to 109 polarization switching cycles, whereas the remnant polarization and coercive force of the rhombohedral PLZT films had already degraded to 80% of their initial values after 108 cycles. 相似文献
7.
Maria C. Gust Leslie A. Momoda Neal D. Evans Martha L. Mecartney 《Journal of the American Ceramic Society》2001,84(5):1087-1092
Microstructural development of thin-film barium strontium titanate (Ba x Sr1– x TiO3 ) as a function of strontium concentration and thermal treatment were studied, using transmission electron microscopy (TEM) and X-ray diffractometry (XRD). Thin films, ∼250 nm thick, were spin-coated onto Pt/Ti/SiO2 /Si substrates, using methoxypropoxide alkoxide precursors, and crystallized by heat-treating at 700°C. All films had the cubic perovskite structure, and their lattice parameters varied linearly with strontium content. Films with higher strontium concentrations had a larger average grain size. In situ TEM heating experiments, combined with differential thermal analysis/thermogravimetric analysis results, suggest that the gel films crystallize as an intermediate carbonate phase, Ba x Sr1– x TiO2 CO3 (with a solid solution range from x = 1 to x = 0). Before decomposition at 600°C, this carbonate phase inhibits the formation of the desired perovskite phase. 相似文献
8.
Noboru Tohge Satoshi Takahashi Tsutomu Minami 《Journal of the American Ceramic Society》1991,74(1):67-71
Ferroelectric films, PbZr x Ti1− x O3 ( x = 0 to 0.6), have been prepared from corresponding metal alkoxides partially stabilized with acetylacetone through the sol-gel process. The films dip-coated in an ambient atmosphere were heat-treated at 400°C for decomposition of residual organics and then at temperatures between 500° and 700°C for crystallization of the films. The perovskite phase precipitated at temperatures above 560°C, accompanied by an increase in dielectric constant. The dielectric constant of the films, which was comparable with that of sintered bodies, showed a maximum (∼620) at around x = 0.52 in PbZr x Ti1− x O3 . These films showed D – E hysteresis, with slightly higher values of coercive field, compared with those of sintered bodies. 相似文献
9.
María José Martín Jesús Mendiola Carlos Zaldo 《Journal of the American Ceramic Society》1998,81(10):2542-2548
Pb1- x Ca x TiO3 (PCaT) thin films have been prepared by pulsed laser deposition (PLD) on Pt/TiO2 /SiO2 /(100)Si, (100)MgO, and Pt/(100)MgO substrates. A Pb deficiency with regard to the target composition occurs in films prepared on heated substrates, while the Ca concentration in the film remains congruent with the target composition. The onset temperature for the Pb loss changes from 250°C using nonsintered targets to 450°C if sintered targets are used; moreover, the sintered targets also produce a low particle density on the film surface (0.4 µm−2 ). Increasing the laser fluence to about 10 J/cm2 improves the crystalline quality of the films. PCaT ( x = 0.24) films obtained by PLD on Si-based substrates have a lattice tetragonality c / a = 1.014, lower than the value obtained in films prepared by other methods. The film tetragonality can be slightly increased to c / a = 1.022 by using MgO substrates and much more efficiently by reducing the Ca concentration, up to reach c / a = 1.048 in Ca free films. The increase of the film tetragonality induces an enhancement of the film orientation with the [001] axis perpendicular to the substrate surface; moreover, the typical values of the spontaneous and remanent polarizations increase up to P r similar/congruent 34 µCcm−2 . 相似文献
10.
Kampurath P. Jayadevan Chi-Yi Liu Tseung-Yuen Tseng 《Journal of the American Ceramic Society》2005,88(9):2456-2460
Nanocrystalline x Ag–(1− x )Ba0.5 Sr0.5 TiO3 (Ag–BST, 0≤ x ≤0.1, where x is the mole fraction of Ag) thin films have been deposited on Pt/Ti/SiO2 /Si substrates by a sol–gel method. The films have been characterized by X-ray diffraction (XRD), scanning electron microscopy, and X-ray photoelectron spectroscopy (XPS). The core-level XPS of oxygen (O1 s ) of the Ag–BST films indicate that an optimum amount of Ag ( x =0.02 or 2 mol%) enhances the binding energy of oxygen, possibly through a mechanism in which the electrophilic oxygen dissociates from the Ag surface and fills the oxygen vacancies. Similarly, the binding energy of Ag (Ag3 d ) shows a shift toward a higher value with increasing Ag up to 4 mol%, probably because of the chemical shift of Ag in BST along the surface layers, surface relaxation, or changes in the Fermi level of small Ag particles in the solid solution range of Ag in BST films ( x ≤0.04). The leakage current density of 2 mol% Ag-added BST (∼10−6 A/cm2 ) is less by about an order of magnitude than pure BST at an electric field of 200 kV/cm. A defect model is proposed to explain the observed leakage current density of Ag–BST films satisfactorily. 相似文献
11.
A qualitative model for the sequence of phase transforma-tions leading to perovskite phase formation in sol–gel-derived PZT thin films is presented. It is suggested that for sol–gel-derived Pb(Zrx Ti1–x )O3 (x = 0.4) thin films, prepared using the molecularly modified alkoxide precursors (MMAP) approach, complete (or partial) conversion of the originally amorphous film into a "pyrochlore" phase, although possible, may not be necessary. Differences between the sequence of phase formation encountered in the tradi-tional (oxide-mix) synthesis and that in chemically derived ceramics are discussed. The sequence of phase formation in these thin films also appears to be intertwined with the texture development in that a (111) PZT texture develop-ment appears to be controlled by nucleation of the perovs-kite phase, assisted by a solid-phase epitaxial effect, and the (100)/(001) texture appears to be growth controlled.x 相似文献
12.
Ulrich Hasenkox Carsten Mitze Rainer Waser 《Journal of the American Ceramic Society》1997,80(10):2709-2713
A flexible chemical solution deposition (CSD) method for the preparation of magnetoresistive La1−x (Ca,Sr)x MnO3 thin films based completely on metal propionates is pre-sented.A number of polycrystalline thin films with varying stoichiometries were deposited on different substrate ma-terials at temperatures between 550° and 850°C. The crys-tallization behavior on selected substrates was found to de-pend on the thin film stoichiometry. Magnetoresistivity and magnetization were measured as a function of temperature. For the selected samples, a magnetic Curie temperature TC, a metal–semiconductor transition, and magnetoresistive behavior were observed. These measurements demon-strated that La1−x (Ca,Sr)x MnO3 thin films with properties well known from films deposited by PLD or sputtering can be prepared by a simple, propionate-based CSD method. 相似文献
13.
Naoto Kikuchi Hideo Hosono Hiroshi Kawazoe Kaiji Oyoshi Shunichi Hishita 《Journal of the American Ceramic Society》1997,80(1):22-26
Amorphous cadmium germanate thin films with the chemical composition x CdO·(100 — x)GeO2 (}20, x , }80 mol%) were prepared by a radio-frequency sputtering method in an ArO2 atmosphere. The electrical and optical properties of the as-sputtered films and films after proton (H+ ) implantation were measured in the temperature range 300–6 K. The optical band gaps of the as-sputtered films were 3.1 eV for all specimens; therefore, they were transparent to visible radiation. Direct-current conductivities of all the films prepared were 10−9 S·cm−1 at room temperature. Upon proton implantation to a fluence of 2 × 1016 cm−2 , the conductivity of the film with x 78 at room temperature was enhanced to 210 S·cm−1 , 11 orders of magnitude greater than the conductivity of the as-sputtered film, and the conductivities remained almost constant to }6 K, whereas those of films with x , }55 remained at 10−9 S·cm−1 . The carrier electron density and the mobility of carriers in the former films, both of which were evaluated from the Hall measurements, were }1 × 1020 cm−3 and 12 cm2 V−1 ·s−1 , respectively. Effects of the chemical composition on persistent photocurrents also were examined. Significant photocurrents were observed in the films with x · }50, and they were greatly enhanced in the films with x · }75. This result indicated that the bottom part of the conduction band, which was composed mainly of 5s orbitals of cadmium cations, was extended for the films with x · }75. 相似文献
14.
通过单因素实验研究了三乙醇胺(N(C_2H_4OH)_3)对恒电位法合成氧化钴/聚苯胺复合膜的影响。采用电化学测试技术、扫描电镜、X射线衍射和加速腐蚀实验等方法对膜层的耐腐蚀性能进行分析。结果表明,恒电位法合成的氧化钴/聚苯胺复合膜中,氧化钴以晶体形式存在,三乙醇胺的加入使复合膜的微观形貌由不致密不规则的片状形貌,转变为均匀致密的片状形貌。三乙醇胺加入2 g/L时,复合膜的自腐蚀电流达到9.09×10~(-7)A/cm~2,自腐蚀电位达到-0.152 V,10%HCl点滴腐蚀时间达496 s,10%NaOH点滴实验时间467 s,中性盐雾实验48 h未见锈蚀。 相似文献
15.
Marcus Hoffmann† Christiane Hofer† Theodor Schneller† Ulrich Böttger† Rainer Waser†‡ 《Journal of the American Ceramic Society》2002,85(7):1867-1869
The aging behavior of the solid-solution series (Pb(Mg1/3 Nb2/3 )O3 )1− x –(PbTiO3 ) x (PMN1− x −PT x ) prepared by chemical-solution deposition without seeding layers was investigated. A strong influence of the rapid thermal annealing step on the film density was determined. The best nucleation and density of the thin films occurred when each deposited layer was separately pyrolyzed and crystallized. The thin-film microstructure was investigated using scanning electron microscopy. Conventional capacitance-voltage and hysteresis measurements were performed. For the first time, investigations on the fatigue performance and the leakage current for alternating-current and direct-current voltage were executed, which are important for the reliability in device applications. 相似文献
16.
Abbas Emamgholizadeh Maryam Khoshroo Abdollah Omrani Abbas A. Rostami 《应用聚合物科学杂志》2010,117(6):3107-3113
In this article, we report polypyrrole (PPy)/poly(vinyl sulfonate) (PVS) and PPy/perchlorate (ClO) composite films generated by the electrochemical oxidation of pyrrole on a glassy carbon electrode (GCE) in an aqueous solution. The response of the produced films to an applied potential at 0.7 V was obtained by a cyclic voltammetry study in acetonitrile media. The films were significantly similar in their electrochemical behavior when ClO ions doped during the redox process. We concluded that with an increasing number of cycles, the anodic current increased because the number of the electroactive participants transported in the copolymer matrix was increased. Theoretical studies based on the Nernst and Butler–Volmer equations indicated that the ClO ion was transported during the oxidation/reduction process of the PPY/PVS and PPY/ClO films. The produced films were characterized further by means of IR spectroscopy, electrochemical impedance spectroscopy, and scanning electron microscopy to verify that the anion of ClO was doped into the copolymer matrix as well. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
17.
18.
Kanichi Kamiya Tomoaki Nishijima Katsuhisa Tanaka 《Journal of the American Ceramic Society》1990,73(9):2750-2752
Dip-coated sol–gel-derived TiO2 films on an alumina substrate were converted to nonstoichiometric titanium nitride (TiN x ( x ≦ 1)) films by heating at approxmately 1000°C in NH3 gas. TiO2 films made from TiO2 sols prepared from Ti(O– i -C3 H7 )4 and stabilized by diethanolamine were more easily nitrided than those from sols containing HCl as a deflocculant reagent. This appears to be a result of the more porous structure of the former films. 相似文献
19.
Summary Asymmetrically disubstituted poly(2-isopropoxy-5-methoxy-1,4-phenylene-vinylene), PIMPV, was prepared in thin films via organic-soluble precursor polymer method. These polymer films could be easily stretched up to 7 times, and the drawn films of the PIMPV could be doped with FeCl3 and I2 to give conductivities of 26.9 and 11.3 Scm-1, respectively. The third-order nonlinear optical susceptibility of the polymer was determined using third harmonic generation(THG) method at 1907 nm, fundamental wavelength. Measured (30) (-3: , , ) value was 3.7x10-12 esu. 相似文献
20.
采用原电池电化学法制备了钨酸锶钙(Sr1–yCayWO4)薄膜。利用X射线衍射仪、能谱仪和荧光计等对薄膜进行分析,并研究了薄膜中钙含量(y)与溶液中钙含量(x)之间的半定量关系。研究表明,所得薄膜为多晶膜,钙占据白钨矿结构的钨酸盐AWO4中A位晶格;可根据经验公式y=0.168+0.79x(0.2≤x≤0.8)来半定量地控制膜中的钙含量。随着x的增加,制备的Sr1–yCayWO4多晶体的形貌由SrWO4的双锥形演变到CaWO4的花束状团簇。在258nm的紫外光激发下,可观测到位于415nm和463nm处的2个发光带;发光强度并不随着x的增加表现出规律性的变化,但当x=0.2时制备的Sr1–yCayWO4薄膜样品的发光强度最大。 相似文献