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1.
Jesús Ricote Rosalía Poyato Miguel Algueró Lorena Pardo M. Lourdes Calzada Daniel Chateigner 《Journal of the American Ceramic Society》2003,86(9):1571-1577
An advanced method of X-ray diffractometry analysis, the quantitative texture analysis, is used in this work to study the preferential orientations of ferroelectric lanthanum-modified lead titanate thin films, to establish the factors affecting their development. The new, more reliable, texture data obtained allows us to discuss previous models of texture development in chemical-solution-deposited films. The results show that a fiber type, mixed <100>,<001> preferential orientation, is obtained when high heating rates are used during crystallization. The degree of texture of these films decreases when successive layers are deposited before a simultaneous crystallization of the ensemble is conducted. This undesirable effect is avoided through layer-by-layer crystallization, because of the preferential nucleation of <100>,<001> crystals at the interface between layers. The use of a titanium layer on the platinized silicon-based substrate leads to the development of an additional fiber <111> texture component. In this case, the layer-by-layer crystallization process cannot avoid the loss of the degree of orientation (texture index) with the increase of film thickness. This is mainly caused by the appearance of interlayer porosity, which disrupts the growth of <111>-oriented grains into upper layers. 相似文献
2.
Solution Chemistry,Substrate, and Processing Effects on Chemical Homogeneity in Lead Zirconate Titanate Thin Films
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Paul G. Kotula Bryan D. Gauntt Dara V. Gough Ping Lu Erik D. Spoerke 《Journal of the American Ceramic Society》2015,98(7):2028-2038
The effects of chemistry, substrate, and processing conditions on through‐thickness cation distributions are explored in solution‐derived morphotropic composition lead zirconate titanate (PZT) films. Films prepared from chelate‐based and conventional sol–gel chemistries were spin cast onto Pt/ZnO/SiO2/Si and Pt/Ti/SiO2/Si substrates and pyrolyzed at 300°C, 350°C, and 400°C prior to crystallization at 700°C either in a preheated furnace or via rapid thermal processing. For films crystallized within a conventional furnace on Pt/ZnO/SiO2/Si substrates no chemical gradients were observed. All films prepared on Pt/Ti/SiO2/Si substrates had increased titanium concentrations near the PZT/Pt interfaces, and the source is shown to be titanium diffusing from the substrate metallization stack. The effect of heating method and rate was explored in films prepared on Pt/ZnO/SiO2/Si substrates with 15°C, 50°C, and 100°C/s heating rates within a rapid thermal annealer. Only one solution chemistry‐heating rate combination resulted in the formation of a chemical gradient: a conventional sol–gel chemistry and a 50°C/s heating rate. Infrared spectroscopy of pyrolyzed gel films showed absorption spectra differences in the bonding structure between the two chemistries with the conventional sol–gel‐derived films exhibiting a signature more similar to that of a PbTiO3 gel, suggestive of a gel‐structure source of gradient formation during crystallization. 相似文献
3.
As a step toward creating a chemical vapor deposition (CVD) process for PbTiO3 thin films, lead oxide films were deposited and then examined. The reaction was oxidation controlled, with an apparent activation energy of 97 kJ/mol in this low-temperature, low-pressure metalorganic CVD (MOCVD) process. Across the deposition parameters examined, several distinct types of morphology were observed. Growth occurred as a combination of layer-on-layer and island formation. The structural and chemical properties of the lead oxide were examined by Auger electron spectroscopy, Raman spectroscopy, X-ray diffraction, scanning electron microscopy, and electron diffraction. Various forms of lead oxide were produced (litharge, massicot, and scrutinyite, singly or in combination with each other). The deposition parameters used in this work showed a tendency to maintain the same crystalline form from the initial nucleation stages through post-deposition annealing. Lead oxide formed readily on SiO2 surfaces (contrary to studies by other researchers) and, indeed, reacted with the underlying SiO2 layer. 相似文献
4.
Altaf H. Carim Bruce A. Tuttle Daniel H. Doughty Sheri L. Martinez 《Journal of the American Ceramic Society》1991,74(6):1455-1458
Lead zirconate titanate (PZT) thin films with a composition near the morphotropic phase boundary (Zr/Ti = 53/47) were fabricated by spin deposition of an alkoxide-derived solution and annealed at 650°C for 30 min. A complex microstructure is observed in which micrometer-scale rosettes of the desired perovskite phase are surrounded by nanocrystalline (10 to 15 nm) grains of pyrochlore structure. Transmission electron microscopy (TEM) demonstrates that the perovskite rosettes—features of approximately circular cross section which grow rapidly within the confined conditions of the thin film—are single crystals despite being highly porous. Pockets of lead-deficient pyrochlore extend throughout the thickness of the film. The only effects of Nb (2%) doping on the microstructure are to increase the fraction of the perovskite phase and the perovskite grain size. Despite the highly irregular shape of the perovskite particles and the presence of some pyrochlore, reasonable ferroelectric properties are measured (spontaneous polarization P s ∼ 0.2 C/m2 ). 相似文献
5.
Cecil E. Land 《Journal of the American Ceramic Society》1989,72(11):2059-2064
The feasibility of storing and reading high-density optical information in lead zirconate titanate (PZT) and in lead lanthanum zirconate titanate (PLZT) thin films depends on both the longitudinal electrooptic coefficients and the photosensitivities of the films. This paper describes the methods used to measure the longitudinal electrooptic effects and the photosensitivities of the films. The results of these measurements were used to evaluate a longitudinal quadratic electrooptic R coefficient, a longitudinal linear electrooptic rc coefficient, and the wavelength dependence of the photosensitivity of a composition of PZT polycrystalline thin film. The longitudinal electrooptic R and rc coefficients are about an order of magnitude less than the transverse R and rc coefficients of bulk ceramics of similar compositions. This is attributed to clamping of the film by the rigid substrate. The large birefringence of the films after poling (>10−2 ) suggests that the optic axes of the films are preferentially oriented normal to the film surface. The techniques used in this paper for evaluating the photosensitivities of thin films are based on measuring the photocurrent generated rather than the reduction in coercive voltage (as in bulk ceramics) when the film is exposed to light. The thin film photosensitivities appear to be significantly higher than those of bulk ceramics of similar compositions. The high photosensitivities coupled with the substantial longitudinal electrooptic coefficients combine to establish the feasibility of using PZT or PLZT thin films for optical information storage applications. 相似文献
6.
Michael B. Sinclair Duane Dimos Barrett G. Potter Jr. Robert W. Schwartz 《Journal of the American Ceramic Society》1995,78(8):2027-2032
The results of light-scattering measurements of a series of Pb(Zr,Ti)O3 thin films prepared by a sol-gel method are presented and analyzed. The films differed due to the addition of different concentrations of acetylacetone to the precursor solution immediately prior to film fabrication. Visual inspection of the films indicated improvements in optical quality with the addition of acetylacetone. To quantify these improvements, two types of light-scattering measurements were performed: angularly resolved light scattering and spectrally resolved light scattering. Surprisingly, only slight differences between the films were observed using angularly resolved light scattering at 633 nm. In contrast, the spectrally resolved scattering revealed large differences between the films, with the films prepared using the largest concentrations of acetylacetone exhibiting the lowest scattering. The apparent contradiction between these findings is resolved using a theoretical model for light scattering due to fluctuations in the dielectric constant occurring within the volume of the thin film and by noting that slight thickness differences exist between the films in the series. Analysis of the light scattering from the best sample yields estimates for the amplitude (ζ0 = 0.08) and the characteristic size (T0 = 110 nm) of the dielectric constant fluctuations. These estimates are consistent with the variations of the dielectric constant expected due to the birefringent, polycrystalline nature of these films. 相似文献
7.
Ming-Ren Huang Cheng-Jien Peng Hong-Yang Lu 《Journal of the American Ceramic Society》2003,86(12):2167-2175
Lead zirconate titanate (Pb(Zr,Ti)O3 , PZT) thin films were grown on silicon 〈100〉 substrate by aerosol plasma deposition (APD) using solid-state-reacted powder containing donor oxide Nb2 O5 when keeping the substrate at room temperature and 200°C. Crystalline phases of the deposited films have been analyzed via X-ray diffractometry (XRD), and microstructure via scanning and transmission electron microscopy (SEM and TEM). Cross-sectional TEM revealed that the microstructure comprised several layers including the deposited PZT film and the platinum-electrode-and-titanium-buffered layers on SiO2 –Si substrate. The Pt-electrode layer contained (111)Pt twinned columnar grains with a slight misorientation and forming low-angle grain boundaries among them. The PZT layer contained randomly oriented grains embedded in an amorphous matrix. Some of the PZT grains, oriented with the zone axis Z = [[Twomacr]11]PZT parallel to Z = [111]Pt , were grown epitaxially on the Pt layer by sharing the (111)PZT plane with the (111)Pt twinned columnar Pt crystals. However, the existence of such an orientation relationship was confined to several nanosize grains at and near the PZT-Pt interface, and no gross film texture has been developed. An amorphous grain boundary phase, generated by pressure-induced amorphisation (PIA) in the solid state, was identified by high-resolution imaging. Its presence is taken to account for the densification of the PZT thin films via a sintering mechanism involving an amorphous phase on deposition at 25° and 200°C. 相似文献
8.
Huiqing Fan Gun-Tae Park Jong-Jin Choi Hyoun-Ee Kim 《Journal of the American Ceramic Society》2002,85(8):2001-2004
A sol–gel-derived Pb(Mg1/3 Nb2/3 )0.7 Ti0.3 O3 (PMNT) thin film was prepared using spin coating and a PbO cover coat technique. The amount of lead excess in the precursor solution had significant effects on the phase development and microstructure of the PMNT film. The PbO cover coat proved to be effective on suppressing the formation of pyrochlore phases. PMNT thin films with a pure perovskite structure were obtained by adding 30 mol% excess lead in the precursor solution and coating the PbO layer on the top of the film. The remnant polarization ( P r ), the dielectric constant (ɛr ), and the dissipation factor (tan δ) of these thin films, which had a thickness of 150 nm, were determined to be 9 μC/cm2 , 1370, and 0.031, respectively. 相似文献
9.
Zhong-Xin Chen Joost van der Eyden† Wouter Koot Rob van den Berg Jan van Mechelen Anke Derking 《Journal of the American Ceramic Society》1995,78(11):2993-3001
Homogeneous thin films of zinc titanate have been successfully prepared on Si(100) wafers by depositing a film of zinc and titanium oxides (ZnO-TiO2 ) by low-pressure metalorganic chemical vapor deposition (MOCVD), followed by an annealing treatment. The precursors used for the deposition were diethylzinc (DEZ), tetraisopropoxide titanium (TPT), and water. By performing the deposition at temperatures between 140 and 350C, the stoichiometry of the as-deposited films could be effectively controlled over Zn/Ti ratios between 0.5 and 2.5, which cover the composition of various zinc titanate phases identified in the literature. The as-deposited ZnO-TiO2 films are amorphous, and possess a fairly smooth surface. XPS and SIMS analysis showed that the composition of these films is uniform over the wafer as well as through the films bulk. An annealing treatment of the as-deposited films at high temperature 相似文献
10.
Aiying Wu Paula M. Vilarinho Isabel M. Miranda Salvado João L. Baptista Zhaoxia Zhou I. M. Reaney Ana R. Ramos Maria F. da Silva 《Journal of the American Ceramic Society》2002,85(3):641-646
Lead zirconate titanate (PZT) thin films were prepared on platinized silicon substrates by dip-coating using a modified diol-based sol–gel route without and with up to 5 mol% PZT nanometric seeds dispersed in the precursor sol. A metastable intermetallic Pt x Pb phase formed at the early stages of heat treatment. XRD, TEM, and RBS revealed that the thickness and stoichiometry of the Pt x Pb layer varied with the concentration of seeds and heat treatment of the films. The relation of the Pt x Pb layer to the final crystalline texture of the PZT thin films is reported and discussed. 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.
《硅酸盐学报》2015,(11)
采用溶胶–凝胶工艺在Pt/Ti/Si O2/Si基片上,通过引入钽镁酸钡[Ba(Mg1/3Ta2/3)O3,BMT]缓冲层,制备了锆钛酸铅[Pb(Zr0.52Ti0.48)O3,PZT]铁电薄膜。研究了BMT缓冲层对PZT铁电薄膜结晶和性能的影响。结果表明:引入BMT缓冲层利于PZT薄膜的生长;PZT薄膜具有钙钛矿结构,且没有裂纹、结晶良好、致密性好;缓冲层的厚度对PZT铁电薄膜的微观结构和铁电性能有重要影响。随BMT缓冲层厚度增加,PZT晶粒增大,介电损耗tanδ逐渐减少,介电常数εr和剩余极化强度Pr先增大后减少,矫顽场Ec先减少后增大。当BMT缓冲层厚约为10 nm时,PZT薄膜具有最优的铁电性能:εr=1 850,Pr=20.2μC/cm2,Ec=43.9 k V/mm。这与BMT与PZT具有相似的晶格常数、较小的晶格失配度和相近的禁带宽度有关。 相似文献
13.
Synthesis and Microstructure of Highly Oriented Lead Titanate Thin Films Prepared by a Sol-Gel Method 总被引:1,自引:0,他引:1
Chiahong Chen Daniel F. Ryder Jr. William A. Spurgeon 《Journal of the American Ceramic Society》1989,72(8):1495-1498
Thin films of PbTiO3 were deposited on fused silica, resistor-grade alumina, and single-crystal (100) MgO by a sol–gel processing method. Whereas the films deposited on silica and alumina substrates were randomly oriented and polycrystalline, highly {100} oriented PbTiO3 films were grown on the MgO single crystals. The perovskite-type structure was observed with films deposited on the single-crystal MgO and annealed at temperatures as low as 470°C, whereas a pyrochlore-type strcuture was observed with films on fused silica and alumina processed in a similar manner. All films heat-treated at temperatures in excess of 570°C showed significant formation of a second PbTi3 O7 phase. The films were characterized by electron microscopy and glancing-incidence-angle X-ray diffraction. 相似文献
14.
Manoch Naksata Rik Brydson Steven John Milne 《Journal of the American Ceramic Society》2003,86(9):1560-1566
Microstructure and phase development during the thermal decomposition of sol–gel precursor coatings of PbZr0.53 Ti0.47 O3 on platinized silicon substrates have been investigated for a triol sol–gel route. The single-layer, 0.4 μm PZT films were heated from below the substrate, over the temperature range 350–600°C, using a calibrated hot plate. The first crystalline phase to appear was a PbPt3 intermetallic phase at the Pt/PZT interface. Although perovskite PZT formed at ca. 500°C, heating at higher temperatures, for example 550°C for 30 min, was required to develop ferroelectric hysteresis loops. However, the rather low value of remanent polarization, P r = 11 μC·cm−2 , was consistent with incomplete crystallization at 550°C. The values of remanent polarization increased with increasing processing temperatures, reaching 21 μC·cm−2 for samples heated at 600°C, with a corresponding E c value of 57 kV·cm−1 . Distinctive spherical precipitates up to ca. 50 nm in size have been identified by TEM in the lower portions of otherwise amorphous coatings, after heating at around 350–400°C. Although their precise composition could not be identified, they were mostly Pb-rich, and it is speculated that they form due to reduction of some of the lead(II) acetate starting reagent, to atomic Pb during the early stages of thermal decomposition of the organic components of the gel; it is possible that subsequent reactions occur to form lead oxides or carbonates. High levels of porosity were present in many of the fully crystallized films. The possible reasons for this are discussed. 相似文献
15.
Yasuhiro Shimizu K. R. Udayakumar L. Eric Cross 《Journal of the American Ceramic Society》1991,74(12):3023-3027
Lanthanum-doped lead titanate thin films have been prepared by sol–gel processing. These studies reveal the structural and electrical properties of 18 mol% La-doped PbTiO3 thin films to be dependent on the annealing conditions. With appropriate annealing conditions, a relative dielectric constant of about 900 was obtained, comparable to the bulk composition. 相似文献
16.
Jian-Gong Cheng Reinhard Gabl Dana Pitzer Robert Primig Matthias Schreiter Wolfram Wersing 《Journal of the American Ceramic Society》2003,86(10):1786-1788
Columnar and (100)-oriented LaNiO3 thin films were prepared on silicon substrates by a chemical solution deposition (CSD) process using a 0.05 M solution. By reducing the individual layer thickness to 10 nm, columnar LaNiO3 films with a lateral grain size of ∼120 nm were obtained. The success of this approach required restricting the individual layer thickness to a value below the grain size observed for equiaxed films. This change in microstructure resulted in an improvement in conductivity. The columnar LaNiO3 film with a thickness of 300 nm showed a resistivity of 4.5 × 10−5 Ω·cm, which is lower by one order of magnitude than that of fine-grain equiaxed films that typically result from CSD methods. 相似文献
17.
Satomi Ono Olaf Böse Wolfgang Unger Yoshikuni Takeichi Shin-ichi Hirano 《Journal of the American Ceramic Society》1998,81(7):1749-1756
Lithium niobate (LiNbO3 , LN) films prepared from aqueous precursor solutions were characterized, in terms of the hydroxyl contents on the surface layers through crystallization and optical properties. Approximately 98% of the hydroxyl residues on the surface layers of crystalline films were polymerized after heat treatment at 350° or 500°C, whereas 50% of the hydroxyl residues remained on the surface layers of amorphous films heat-treated at 200°C. Highly preferred oriented LN films had a tendency to consist of in-plane rotation by 60° during nucleation and crystallization. Optical losses (at 632.8 nm) were 2 dB/cm in the TE0 mode and 4 dB/cm in the TM0 mode of the LN films (thickness of 670 nm) on sapphire (001) substrates prepared from a neutralized precursor solution after annealing in oxygen at a temperature of 500°C (where TE and TM are the transverse electric and magnetic modes, respectively). 相似文献
18.
Origin of Orientation in Sol-Gel-Derived Lead Titanate Films 总被引:3,自引:0,他引:3
Keiko Kushida K. R. Udayakumar S. B. Krupanidhi L. Eric Cross 《Journal of the American Ceramic Society》1993,76(5):1345-1348
The origin of orientation in sol-gel-derived PbTiO3 films is investigated in detail. Aging of the solution is found to promote (100) orientation of the films. Characterizing the solution by viscometry indicates that the preferred orientation might be attributable to the change of molecular size in the solution. The substrate also influences the film orientation: more strongly (100)-oriented film forms on Pt-coated Si than on fused quartz. Highly c -axis-oriented films with azimuthal orientation are grown on a (100) SrTiO3 single-crystal disk. 相似文献
19.
Use of Ferroelectric Hysteresis Parameters for Evaluation of Niobium Effects in Lead Zirconate Titanate Thin Films 总被引:1,自引:0,他引:1
Radosveta D. Klissurska Alexander K. Tagantsev Keith G. Brooks Nava Setter 《Journal of the American Ceramic Society》1997,80(2):336-342
The effects of niobium doping on the hysteresis parameters of sol—gel Pb1.1−(x/2) (Zr0.53 Ti0.47 )1−x Nbx O3 (0, x, 0.05) have been reported for two sets of films with analogous grain size and degree of (111) texture but with different surface microstructures. For both sets, a strong continuous decay of the remnant and maximum polarizations and slope of the hysteresis loop at the coercive field was observed with increasing niobium concentration. The field dependence of the remnant polarization for any given niobium-doped film was identical to the functional field dependence of the undoped reference film, if multiplied by a niobium-concentration-dependent constant. Although the maximum and remnant polarizations decayed as the dopant level increased, their difference remained the same value as that of the undoped film at any given field. The width of the loop (at zero polarization) was insensitive to the niobium concentration at any given field. A linear increase in coercive field asymmetry (up to 40 kV/cm) was observed with niobium addition, yet was field independent and, thus, electrostatic in origin. Niobium governed switching through a reduction of the number of switching domains, without changing the total lattice polarization response. Microstructure-related effects on switching, such as decreased volume fraction of ferroelectric material or field-screening effects due to the presence of a pyrochlore second phase, were eliminated as the origin of the hysteresis changes. This paper has demonstrated how hysteresis features and their field dependencies can be used to separate the effects of niobium-induced microstructural changes from niobium lattice doping influences on the hysteresis loops. 相似文献
20.
将铌镁酸钡(Ba(Mg1/3Nb2/3)O3,BMN)作为缓冲层,通过溶胶-凝胶法制备了锆钛酸铅(Pb(Zr0.52Ti0.48)O3,PZT)铁电薄膜.探究BMN缓冲层对PZT铁电薄膜介电、铁电性能影响.研究发现:BMN缓冲层不仅可以改善PZT薄膜晶化生长,同时阻碍了PZT与Pt的互扩散而降低了漏电流.由于对漏电流的抑制作用,适当厚度BMN缓冲层的引入可改善PZT的铁电性能,但随着缓冲层厚度的增加,由于其分压作用,复合膜铁电性减弱.当厚度为10 nm时,薄膜的综合性能最好:介电常数εr=1612.03,介电损耗tanδ=0.024,剩余极化值Pr=31.65 μC/cm2,矫顽场Ec=71.5 kV/cm,漏电流密度J=4.4×10-6 A/cm2. 相似文献