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1.
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
2.
Lead zirconate titanate (PZT) thin films were deposited by metal-organic chemical vapor deposition (MOCVD) using β-diketonate precursors and 02 at temperatures below 500°C on variously passivated Si substrates. PZT thin films could not be deposited on bare Si substrates, owing to a serious diffusion of Pb into the Si substrate during deposition. Pt/SiO2 /Si substrates could partially block the diffusion of Pb, but a direct deposition of PZT thin films on the Pt/SiO2 /Si substrates resulted in a very inhomogeneous deposition. A TiO2 buffer layer deposited on Pt/SiO2 /Si substrates could partially suppress the diffusion of Pb and produce homogeneous thin films. However, the crystallinity of PZT thin films deposited on the TiO2 -buffered Pt/SiO2 /Si substrate was not good enough, and the films showed random growth direction. PZT thin films deposited on the PbTiO3 -buffered Pt/SiO2 /Si substrates had good crystallinity and a- and c-axis oriented growth direction. However, the PZT thin film deposited at 350°C showed fine amorphous phases at the grain boundaries, owing to the low chemical reactivities of the constituent elements at that temperature, but they could be crystallized by rapid thermal anneaiing (RTA) at 700°C. PZT thin film deposited on a 1000-å PbTiO3 ,-thin-film-buffered Pt/SiO2 /Si substrate at 350°C and rapid thermally annealed at 700°C for 6 min showed a single-phase perovskite structure with a composition near the morphotropic boundary composition. 相似文献
3.
Low-Temperature Crystallization of Sol-Gel Processed Pb0.5 Ba0.5 TiO3 : Powders and Oriented Thin Films
Suresh C. Pillai Stacey W. Boland Sossina M. Haile 《Journal of the American Ceramic Society》2004,87(7):1388-1391
A novel sol-gel process suitable for depositing thin-film lead barium titanate has been developed. X-ray diffraction analysis showed perovskite phase crystallization to occur at a temperature as low as 400°C with single-phase Pb0.5 Ba0.5 TiO3 (PBT) resulting at a temperature as low as 500°C. Small concentrations of barium carbonate were evident by X-ray diffraction at 400°C, and indications of minor, carbonate-containing phases were evident by FTIR at 600°C. Deposition of the sol by spin coating on single-crystal and thin-film MgO on silicon resulted in highly oriented PBT films after calcination at 600°C. Mixed (100)/(001) films were obtained on single-crystal MgO, whereas entirely (100) films were obtained on thin-film MgO. 相似文献
4.
The interfaces between metal organic chemical vapor deposited PbTiO3 thin films and various diffusion barrier layers deposited on Si substrates were investigated by transmission electron microscopy. Several diffusion barrier thin films such as polycrystalline TiO2 , amorphous TiO2 , ZrO2 , and TiN were deposited between the PbTiO3 thin film and Si substrate, because the deposition of PbTiO3 thin films on bare Si substrates produced Pb silicate layers at the interface irrespective of the deposition conditions. The TiO2 films were converted to PbTiO3 by their reaction with diffused Pb and O ions during PbTiO3 deposition at a gubstrate temperature of 410°C. Further diffusion of Pb and O induces formation of a Pb silicate layer at the interface. ZrO2 did not seem to react with Pb and O during PbTiO3 deposition at the same temperature, but the Pb and O ions that diffused through the ZrO2 layer formed a Pb silicate layer between the ZrO2 and Si substrate. The TiN films did not seem to react with Pb and O ions during the deposition of PbTiO3 at 410°C, but reacted with PbTiO3 to form a lead-deficient pyrochlore during postdeposition rapid thermal annealing at 700°C. However, TiN could effectively block the diffusion of Pb and O ions into the Si substrate and the formation of Pb silicate at the interface. 相似文献
5.
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
6.
PbTiO3 and PbTiO3 /polymer thin films were synthesized from metallo-organic precursors on metallized quartz substrates. Titanium dimethoxy dineodecanoate (TDD) was spin-cast onto the substrates and converted to polycrystalline TiO2 via hydrolysis in deionized water for 5 h at 80°C. Polycrystalline PbTiO3 films were then formed by reacting the TiO2 films for 4 h at 200°C in aqueous solutions of KOH and Pb(CH3 COO)2 ·3H2 O. Low KOH concentrations suppressed film coarsening, thereby facilitating the formation of fine-grain continuous PbTiO3 films. PbTiO3 /polymer thin films were processed as above after first dissolving TDD and a polystyrene/polybutadiene block copolymer in p -xylene. PbTiO3 and PbTiO3 /polymer films had relative permittivities of ≈56 and 34 and dielectric strengths of ≈250 and 850 kV/cm, respectively. 相似文献
7.
Toshinobu Yogo Wataru Sakamoto Tadayuki Isaji Masao Ichida Arao Nakamura Shin-ichi Hirano 《Journal of the American Ceramic Society》1999,82(10):2672-2676
Ba2 NaNb5 O15 (BNN) thin films with a tungsten bronze structure were fabricated using a precursor solution that was synthesized from barium, sodium, and niobium alkoxides. Highly (002)-oriented BNN films were prepared successfully on Pt(100)/MgO(100) substrates at 700°C, using a BNN underlayer. X-ray pole-figure measurement showed that the BNN films that crystallized on Pt(100)/MgO(100) substrates had two in-plane orientations. The remanent polarization and coercive field of the BNN film (thickness of 1.0 µm) that was crystallized at 700°C were 12.3 µC/cm2 and 101 kV/cm, respectively, at –150°C (123 K). BNN films on fused silica substrates exhibited second harmonic generation upon irradiation with 1064 nm light. 相似文献
8.
Crystalline PbTiO3 thin films were successfully deposited on (111)-oriented Pt/Ti/SiO2 /Si and on (200)-oriented Pt/SiO2 /Si by metalorganic chemical vapor deposition at a substrate temperature of 400°C, using a β-diketonate complex of Pb(tmhd)2 (tmhd = 2,2,6,6-tetramethyl-3,5-heptanedionate) and titanium isopropoxide as source precursors. The dependence of the formation of crystalline PbTiO3 phase on the Pb/Ti input precursor ratio is qualitatively described. The structure of the films deposited at 400°C changed from amorphous to polycrystalline with an increase of the Pb/Ti ratio from 1.1 to 5.0, including a partially crystallized structure at some intermediate ratio. Partial crystallization of as-grown PbTiO3 film was analyzed by scanning electron microscopy, micro-Raman, and Auger electron spectroscopy measurements. It was found that the control of excess Pb precursor through a change in the Pb/Ti ratio is the key process parameter for the formation of crystalline PbTiO3 phase in the low-temperature MOCVD process. 相似文献
9.
Potassium tantalate–niobate solid-solution (KTN) powders and thin films were prepared from metallo–organic compounds through sol–gel processing. The KTN precursors were chemically modified and then prehydrolyzed with various concentrations of water. The stability of the modified solutions and the effects of prehydrolysis on the crystallization are discussed. Powder gels were obtained by exposing the solution to the atmospheric water, hydrolyzing the solutions. Alternatively, thin films were deposited on fused silica, silicon, sapphire, MgO, and SrTiO3 , using the spinning technique. The pyrolysis and crystallization of KTN powders and films were investigated by differential thermal analysis, theromogravimetric analysis, and X-ray diffraction. The effects of substrate and other processing parameteres on the crystal structure of the KTN phases were also investigated. KTN powders crystallized into a perovskite phase regardless of the processing conditions. The crystal structure of the KTN thin films had a strong dependency on the crystal structure of the substrates, while other processing parameters played smaller roles. Pyrochlore KTN was the major phase that crystallized on fused silica and silicon, whereas oriented perovskite KTN was obtained on single-crystal MgO and SrTiO3 . 相似文献
10.
Tao Li Adam M. Scotch Helen M. Chan Martin P. Harmer Seung-Eek Park Thomas R. Shrout Joseph R. Michael 《Journal of the American Ceramic Society》1998,81(1):244-248
A potentially more cost-efficient method of growing single-crystal relaxor-based ferroelectric materials has been investigated. Seed single crystals of Pb(Mg1/3 Nb2/3 )O3 (PMN)—;35 mol% PbTiO3 (PT) were embedded within polycrystalline powders and annealed at temperatures from 900° to 1200°C. The boundary of the single crystal migrated through the polycrystal matrix under the influence of grain boundary curvature; growth distances of several millimeters were observed, verifying the feasibility of the approach. The grown single crystals exhibited macroscopic cubic growth morphologies with (100) faces. Strain levels as high as 0.68% under an electric field of 30 kV/cm were observed in initial measurements. 相似文献
11.
M. Grant Norton Kathryn P. B. Cracknell C. Barry Carter 《Journal of the American Ceramic Society》1992,75(7):1999-2002
Barium titanate (BaTiO3 ) thin films have been deposited on single-crystal magnesia (MgO) substrates by pulsed-laser ablation. Temperature dependence of capacitance measurements show a peak of 110°C, indicative that a ferroelectric phase transition has occurred at this temperature. This value is lower than that determined for single-crystal BaTiO3 , but consistent with that found for BaTiO3 thin films produced by other methods. It has been demonstrated that the microstructure of the films can be varied by changes in the deposition parameters. Optimizing these variations permits the formation of thin films with controlled microstructures and properties. 相似文献
12.
Oriented Lead Titanate Film Growth at Lower Temperatures by the Sol-Gel Method on Particle-Seeded Substrates 总被引:2,自引:0,他引:2
Jooho Moon Jeffrey A. Kerchner James LeBleu Augusto A. Morrone James H. Adair 《Journal of the American Ceramic Society》1997,80(10):2613-2623
An approach to fabricate lead titanate (PbTiO3 ) films with preferred orientation on arbitrary substrates by a sol-gel method was developed. To ensure a preferred crystallographic orientation on the substrates with different crystal structure, well-defined platelet PbTiO3 particles were used as seeds. Because the basal plane of the platelet-shaped particles was the (001) plane, the particles aligned with the c-axis perpendicular to the substrates. During crystallization of the sol-gel PbTiO3 films on the particle-seeded substrate, preferential nucleation occurred on seeded particles with the same crystallographic orientation as the particles at a much lower temperature. In the current study, (100) and (001) textured PbTiO3 films have been produced on various substrate materials such as silicon, silicate glass, indium tin oxide (ITO) glass, and titanium metal at temperatures as low as 275°C. The microstructure of the films was examined by scanning electron microscopy and atomic force microscopy. Limited ferroelectric properties also were determined, to underscore the preferred orientation that was produced in these materials. 相似文献
13.
Wataru Sakamoto Toshinobu Yogo Koichi Kikuta Ko-ji Ogiso Akihiro Kawase Shin-ichi Hirano 《Journal of the American Ceramic Society》1996,79(9):2283-2288
Highly oriented Sr0.5 Ba0.5 Nb2 O6 (SBN50) thin films have been prepared using a sol-gel method. A homogeneous and stable strontium barium niobate (Sr1-x Bax Nb2 O6 , SBN) precursor solution could be prepared via the reaction control of metal alkoxides. The SBN precursor was stabilized by the coordination of the 2-ethoxyethoxy group to metals. SBN thin films on MgO(100) crystallized to a mixture of orthorhombic and tetragonal phase at 700°C and then transformed completely to the tetragonal phase of tungsten bronze at 1000°C. Two crystal lattice planes of SBN were intergrown at an orientation of 18.5° on MgO(100). SBN50 thin films on Pt(100)/MgO(100) substrates exhibited the P-E hysteresis. 相似文献
14.
Sverre M. Selbach Guozhong Wang Mari-Ann Einarsrud Tor Grande 《Journal of the American Ceramic Society》2007,90(8):2649-2652
A lead titanate (PbTiO3 ) precursor, prepared by the Pechini method, has been heat treated to study the transformation from amorphous to crystalline PbTiO3 . Nucleation of PbTiO3 in the temperature interval 400°–475°C occurred before completion of the thermal decomposition of the polymeric precursor, resulting in nanocrystalline PbTiO3 with an unexpectedly high tetragonality ( c/a ratio). Annealing and crystallite growth at 600°C resulted in an increasing c/a ratio with annealing time in line with the expected finite size effect of PbTiO3 . The unusually high c/a ratios observed in PbTiO3 nucleated at 400°–475°C are discussed in relation to partial reduction and point defects in PbTiO3 . 相似文献
15.
Qifa Zhou Qingqi Zhang Baomin Xu Susan Trolier-McKinstry 《Journal of the American Ceramic Society》2002,85(8):1997-2000
Ferroelectric 0.7Pb(Mg1/3 Nb2/3 )O3 –0.3PbTiO3 (PMN-PT) thin films were deposited on ZrO2 /SiO2 /silicon substrates using a chemical-solution-deposition method. Using a thin PZT film as a seed layer for the PMN-PT films, phase-pure perovskite PMN-PT could be obtained via rapid thermal annealing at 750°C for 60 s. The electrical properties of in-plane polarized thin films were characterized using interdigitated electrode arrays on the film surface. Ferroelectric hysteresis loops are observed with much larger remanent polarizations (∼24 μC/cm2 ) than for through-the-thickness polarized PMN-PT thin films (10–12 μC/cm2 ) deposited on Pt/Ti/Si substrates. For a finger spacing of 20 μm, the piezoelectric voltage sensitivity of in–plane polarized PMN-PT thin films was ∼20 times higher than that of through-the-thickness polarized PMN-PT thin films. 相似文献
16.
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
17.
Duk Hee Kim Woo Sik Um Kwangsoo No Ho Gi Kim 《Journal of the American Ceramic Society》1991,74(9):2102-2106
Superconducting Bi(Pb)-Sr-Ca-Cu-O powders were prepared by the emulsion-drying method The powders consisting of the low- T c phase (Bi(Pb)2 Sr2 Ca1 Cu2 Oy ) and small amount of Ca2 PbO4 were prepared by calcining under low oxygen partial pressure at 750°, 800°C. These calcined powders were used to prepare thick films on single-crystal MgO(100) substrates using a screen-printing technique to study the effect of the calcinations temperature and annealing procedure on the high-Tc phase (Bi(Pb)2 Sr2 Ca2 Cu3 Oy )formation. The formation of high-Tc phase was observed to be dependent on the calcinations conditions. The high- Tc phase formed very quickly (sintering at 840°C for 4 h), and the best films showed a sharp superconducting transition at about 105 K. 相似文献
18.
B. N. SAMADDAR W. D. KINGERY A. R. COOPER JR. 《Journal of the American Ceramic Society》1964,47(5):249-254
Experimental measurements have been made on the rate of dissolution of sapphire, dense poly-crystalline alumina, mullite, fused silica, and anorthite in a 20A12 O3 -4OCaO-40SiO2 slag at 1350° to 1500° C under conditions of free and forced convection. Dissolution rates and their temperature dependence were found to be controlled by transport within the liquid boundary layer. At low temperatures alumina is by far the most corrosion resistant; at higher temperatures differences between the refractories tested are less pronounced. 相似文献
19.
Nanoparticles of strontium titanates (SrTiO3 , Sr2 TiO4 ) and lead titanate (PbTiO3 ) have been obtained using reverse micelles as nanoreactors. Powder X-ray diffraction studies of the powders after calcining at 800°C show monophasic SrTiO3 , Sr2 TiO4 , and PbTiO3 . X-ray line broadening studies and transmission electron microscopic studies show spherical grains of 30–40 nm size for strontium titanates, while PbTiO3 is obtained in the form of nanorods. The dielectric constant of SrTiO3 and Sr2 TiO4 is found to be 90 and 30, respectively, (at 100 kHz) for samples sintered at 1000°C. PbTiO3 shows a dielectric constant of 160 (at 100 kHz) after sintering at 900°C. The dielectric constant of Sr2 TiO4 (with temperature) is highly stable. The temperature variation studies of the dielectric constant of PbTiO3 show a ferroelectric phase transition at 490°C (1 kHz). The T c varies with frequency and is found to decrease to 470°C at 100 kHz. 相似文献
20.
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