Photochemical growth of silver nanoparticles on c(-) and c(+) domains on lead zirconate titanate thin films

The photochemical growth of silver nanoparticles on the negative domains of lead zirconate titanate thin films is reported. A sample of highly [100] orientated lead zirconate titanate, with a ratio of 30:70, that was 65-70 nm thick grown on Pt-coated MgO was poled by use of piezoresponse force microscopy to produce defined regions of surface positive and negative polarization. A comparison between the growth of silver nanoparticles on the surface of the lead zirconate titanate when illuminated with two sources of super band gap UV is given. In both cases the wavelength of illumination leads to growth on the positive domains but only illumination with a Honle H lamp, with a high photon output over 250-200 nm, caused significant growth of silver nanoparticles on the negative domain. The deposition on the negative domain is explained in terms of changed band bending due to the excitation of electrons into the conduction band, the rate of decay to the ground state, and dimensions of the ferroelectric film. The rate of deposition of silver nanoparticles on the negative domains is approximately half that on the positive domains.     

The differential thermal analysis behavior of lead zirconate titanate materials

Differential thermal analysis has been used to examine the reactions involved in the formation of lead zirconate titanate and related materials. The reaction of PbO and TiO₂ produced an exothermic peak near 600°C, while mixtures of PbO and ZrO₂ gave endothermic peak at 760°C. Lead titanate and lead zirconate mixtures showed no evidence of reaction below 900°C. Evidence is presented which suggests that PbO and PbTiO₃ react in the vicinity of 750°C. For ternary mixtures of PbO, titanate, the thermograms indicate a complicated behavior between 600–800°C, depending on the ratios of the reactant materials. The results suggest that the calcination reaction to form lead zirconate titanate is a more complex process than has been recognized. Data on the various phase transitions for the lead zirconate titanate materials are also presented.     

Dielectric and Ferroelectric Properties of Sol-Gel Derived YMnO3 Films

There has been considerable interest in ferroelectric (FE) films especially for non-volatile memories and ultra high density DRAM applications. Such FE films typically consist of lead zirconate titanate (PZT) with novel oxide contacts, or layered perovskite such as Sr2Bi2TaO9. Recently, there have been reports of sputtered YMnO3 films which exhibit a single polarization axis and do not contain any volatile species of Pb or Bi. Single crystal YMnO3 exhibits satisfactory polarization (6 C/cm2) and low coercive field (<20 kV/cm). Additionally, the dielectric constant of YMnO3 is quite low (<30) which should facilitate ferroelectric switching. In this study, sol-gel derived YMnO3 films were prepared on platinized Si wafers and their dielectric and ferroelectric properties were characterized. Their electrical properties will be discussed with respect to Y/Mn stoichiometry ratio, hexagonal phase development and processing conditions. The potential of YMnO3 as a material in non-volatile memories is evaluated.     

Synergistic effects on polyurethane/lead zirconate titanate/carbon black three-phase composites

Synergistic processes in hybrid composites have frequently been described in the literature over the past few years, opening doors to new studies and applications for this type of material. In this study, three-phase composites were obtained using polyurethane (PU) as the matrix, lead zirconate titanate (PZT) as the ferroelectric ceramic and carbon black (CB) as the conductive phase. The discussion is primarily focused on a comparison of the electrical, thermal and dielectric properties of three-phase composites with those of PU_CB and PU_PZT biphasic composites. The study describes a synergistic effect between the PU/PZT/CB phases involved in the generation of charges between the particles, implying better homogeneity of the composites as well as influence over the PU crystallization. The PU_CB conductivity profile showed a phenomenon of multi-step percolation thresholds attributed to the molecular structure and repulsive surface charge of CB particles. The surface charge phenomenon restricted the percolation curve analysis of the three-phase composites by means of classic percolation theory, shown by distortion of the critical exponents. The dielectric constant three-phase composites increased gradually as a function of CB in accordance with the percolation profile.     

Structural, morphology and electrical studies of Sm-modified bismuth titanate thin films on Si (100)

Samarium-substituted bismuth titanate (Bi_3.15Sm_0.85Ti₃O₁₂ (BSmT)) thin films have been grown on n-type Si (100) substrates by metalorganic decomposition and spin-coating technique. X-ray diffraction and scanning electron microscopy (SEM) analyses confirmed that the crystallinity of the films increases with increasing annealing temperature and the optimum temperature was found to be 700°C. The Raman measurement showed an increase in structural distortion due to the changed ionic radius and atomic mass of Sm ions. The current-voltage characteristics displayed good insulating properties for a film annealed at 700°C for 1 h. The capacitance-voltage characteristic hysteresis curves revealed that the ferroelectric property sufficiently controlled the silicon potential. The measurements of the dielectric constant and dissipation factor of BSmT as a function of frequency exhibited excellent dielectric properties.     

聚氨酯与铁电陶瓷粉复合物的电致感应性能研究

利用双辊制备了一系列热塑性弹性体聚氨酯（PU）和铁电钛酸锆酸铅盐（PZT）的电感应PZT／PU复合物。X－衍射和SE镜结果显示,复合物中,在铁电相中PZT陶瓷粉呈现结晶态并且均匀分布在PU基体中,复合物的弹性模量和相对电容率随着复合物中PZT体积分数增加而升高,在高压电场下,低PZT含量的复合物呈现负的电致伸缩应力,当PZT体积分数增加到6％以上时,在某个临界电场下,复合物呈现出电致伸缩应力反转的特性,即电致伸缩应力从负转变为正,并且发生应力反转的临界电场随着复合物中PZT体积分数的增加而降低,PU的电致伸缩特性与PZT在高电场下极化反转效应结合,导致了PZT／PU复合物这种有趣的性能,因此PZT／PU复合物将在高电压场方面作为传感器开关材料得到广泛应用。     

A novel route to perovskite lead zirconate titanate from glycolate precursors via the sol–gel process

A perovskite lead zirconate titanate was synthesized by the sol‐gel process, using lead glycolate, sodium tris(glycozirconate) and titanium glycolate as the starting precursors. For the mole ratio Pb:Zr:Ti of 1:0.5:0.5 [Pb(Zr_0.5Ti_0.5)O₃], TGA‐DSC thermal analysis indicated that the percentage of ceramic yield was 55.8, close to the calculated chemical composition value of 49.5. The exothermic peak occurred at 268 °C below the theoretical Curie temperature of 400 °C. The pyrolysis of Pb(Zr_0.5Ti_0.5)O₃ of the perovskite phase was investigated in terms of calcination temperature and time. The structure obtained was of the tetragonal form when calcined at temperatures below 400 °C; it transformed to the tetragonal and the cubic forms of the perovskite phase on calcination above the Curie temperature, as verified by X‐ray data. The lead zirconate titanate synthesized and calcined at 400 °C for 1 h had the highest dielectric constant, the highest electrical conductivity and the dielectric loss tangent of 10 190, 0.803 × 10^?3 (Ω.m)^?1 and 1.513 at 1000 Hz, respectively. The lead zirconate titanate powder synthesized has potential applications as an electronic material. Copyright © 2008 John Wiley & Sons, Ltd.     

Spatially selective photochemical reduction of silver on nanoembossed ferroelectric PZT nanowires

It is well known that photochemical reaction in an aqueous solution can be chosen by selectively patterning the domain structures of ferroelectrics. In this work, we investigate the photochemically induced deposition of Ag particles on ferroelectric lead zirconate titanate [Pb(Zr(x),Ti(1?-?x))O(3)] nanowires fabricated by nanoembossing technology. The photochemical reduction of Ag particles is found to occur preferentially along the embossed nanowires. By imaging domain configurations of the embossed films using the piezoresponse force microscope, the spatially selective deposition of Ag particles can be associated with the underlying ferroelectric domain structures created by the nanoembossing process. The controllable and selective deposition of metal species onto nanoembossed ferroelectric nanostructures without the need for an external electrical field is promising for providing a new route to nanoferroelectric lithography.     

Dielectric and Pyroelectric Properties of Compositionally Graded Pb(Zr1-xTix)O3 Thin Films Prepared by Sol-gel Process

"Compositionally graded ferroelectric lead zirconate titanate Pb(Zr1-xTix)O3 (PZT) thin films were grown on Pt/Ti/SiO2/Si substrates by using a sol-gel process. The final structure consists of six layers, up-graded graded films starting from PbZrO3 on the Pt electrode to the top PZT(50) layer, it consists of no Ti, 10%Ti, 20%Ti, 30%Ti, 40%Ti, and 50%Ti respectively. Whereas films with opposite gradient are called down-graded graded films. Structure and dielectric properties of the graded films was investigated by X-ray diffraction, Auger electron spectroscopy and by impedance analysis. The up-graded and down-graded PZT films annealed at 600 o, exhibited the remanent polarization values of 18.0 and 24.2 1C/cm2, respectively. The typical small signal dielectric constants and loss tanffi at a frequency of 100 Hz were 523 and 0.018, 544, and 0.020, respectively, for up-graded and down-graded PZT thin films. The temperature dependence of pyroelectric coeoients of the graded PZT films was measured by a dynamic technique. From 20 o to 82 o, the pyroelectric coeoients of the up-graded and down-graded PZT films up to 374 and 407 1C/m2K, respectively."     

Synthesizing nanostructured crack-free thick films of Fe-doped lead zirconate titanate by sol–gel dip coating method

Journal of Sol-Gel Science and Technology - Lead zirconate titanate is one of the most well-known ferroelectric oxides and has been widely used in nano/micro-electromechanical systems and...     

Ultra light tunable capacitor based on PZT thin film deposited onto aluminium foil

Lead zirconate titanate (PZT) thin films with a Zr/Ti ratio of 57/43, elaborated by a derived sol–gel process, have been deposited onto bare and RuO₂ coated aluminium substrate 16 μm thick. Commercial aluminium foil presents many advantages as ultra light weight (43 g m^?2), conformability, conduction, can be easily cut, and is one of the cheapest substrates used for PZT thin films deposition (<0.1$ m^-2). XRD measurements have shown a well crystallized PZT in the perovskite structure and ferroelectric behaviour has also been observed. By the use of a RuO₂ film 100 nm thick at the PZT/aluminium interface, the coercive field and tunability values have been strongly improved despite an increase of the dielectric losses. The lead excess introduced in the precursor solution has been increased up to 65 % in order to lower the crystallization temperature of the PZT around 560 °C and tunability has been studied as a function of annealing time and temperature.     

Single-crystal-like materials by the self-assembly of cube-shaped lead zirconate titanate (PZT) microcrystals

We demonstrated the formation of single-crystal-like materials that contain preferentially oriented arrays of lead zirconate titanate (PZT) cube-shaped particles by self-assembly. Hydrothermally synthesized PZT particles with a bulk composition of Zr/Ti = 70/30 were used in making microcrystal arrays. Spreading a suspension containing PZT cube-shaped particles, 2-propanol, and mineral oil at the air-water interface produced a one-dimensional planar array of PZT particles on the water surface. The array so formed was subsequently transferred onto a flat or curved substrate. X-ray diffraction and electron backscattered diffraction analyses revealed that most of the cube-shaped particles in the array were oriented with their pseudocubic (001) direction aligned parallel to the normal direction of the substrate surface. Filling the arrays with matrixes produced monolayer or multilayer textured composites. The piezoelectric properties of oriented cube-shaped micron-sized particles in the self-assembled arrays were measured using a modified atomic force microscope to reveal the ferroelectric nature of the PZT arrays.     

Influence of the process parameters on the structural and electric properties of ferroelectric and antiferroelectric PZT thin films realized on stainless steel by a Sol–gel derived method

Pb _x Zr_yTi_1−yO₃ thin films were prepared by a modified Sol–gel method using alkoxides precursor compounds and spin-coating onto RuO₂ coated stainless steel substrates. Depending on the zirconate/titanate ratio, both, ferroelectric and antiferroelectric behaviour has been obtained. Oxidation of the metal substrate due to the PZT crystallization process was studied in order to verify the influence of the heat treatment on the substrate morphology. In order to improve the properties of antiferroelectric Pb _x Zr_0.95Ti_0.05O₃, the influence of the lead excess in the composition was investigated. Thefs dependence of the switching field distribution from the annealing time and temperature, as well as the fatigue behaviour of the films, is discussed.     

Study by Rutherford Backscattering Spectroscopy of the Heterostructure of Lead Titanate Thin Films

A depth profile analysis of modified lead titanate thin films was performed by means of Rutherford Backscattering Spectroscopy (RBS). These films were deposited from sol-gel synthesized solutions onto platinized silicon substrates and crystallized by thermal treatments at temperatures of about 650°C. The chemistry of the solution and the thermal treatment for crystallization affect the heterostructure of the resulting films. Losses of lead and formation of substrate-film interfaces are produced during the crystallization of the films. These film characteristics determine their ferroelectric response.     

Notes of the recent structural studies on lead zirconate titanate

Atomic scale structure has a central importance for the understanding of functional properties of ferroelectrics. The X-ray and neutron diffraction studies used for the average symmetry determination of lead zirconate titanate [Pb(ZrxTi(1- x))O3, PZT] ceramics and powders are reviewed. The results obtained through two frequently used local probes, transmission electron microscopy (TEM) combined with electron diffraction (ED) and Raman scattering measurements, are summarized. On the basis of these studies, structural trends as a function of composition x and temperature are outlined. There are two distinguished intrinsic structural features, (i) lead-ion shifts and (ii) local structural distortions related to different B cations and the spatial composition variation of x, which have a pronounced effect on the functional properties of PZT. Particular attention is paid to the morphotropic phase boundary (MPB) compositions for which a large number of different structural models have been proposed. Earlier symmetry considerations show that the monoclinic phase cannot serve as a continuous bridge between tetragonal and rhombohedral phases. This suggests that the two-phase coexistence has an important role for the piezoelectric properties. Near the MPB, the extrinsic contribution to piezoelectricity includes pressure (or electric-field)-induced changes in phase fractions and domain wall motion. It was recently shown that the domain contribution is crucial for the electromechanical properties of PZT in the vicinity of the MPB. The dependence of domain widths on crystal size and shape should also be properly accounted for when TEM/ED measurements complement X-ray and/or neutron diffraction experiments. The structure-piezoelectric property relations are summarized.     

Novel single-source precursors for the fabrication of PbTiO3, PbZrO3 and Pb(Zr(1-x)Ti(x))O3 thin-films by chemical vapor deposition

Lead titanate, lead zirconate, and lead zirconate titanate (PZT) films in the sub-μm-range were produced at temperatures around 400 °C using novel single-source precursors in a classical thermal CVD process. The design of two bimetallic alkoxide compounds, a lead titanate and a lead zirconate source with almost identical physical properties and complement miscibility, resulted in a new quasi-single-source PZT precursor, an azeotropic mixture that evaporates at 30 °C and at a pressure of 4 × 10(-1) mbar. After thermal treatment at 650 °C, transparent (100)-oriented PZT films with remnant polarization of 20 μC cm(-2) and a coercive field strength of 20 V μm(-1) were achieved. An additional lead source is not required.     

Electrorheology and characterization of acrylic rubber and lead titanate composite materials

Oxide one‐pot synthesis was used to synthesize a polymer precursor to lead titanate, PbTiO₃. Perovskite lead titanate, PbTiO₃, was synthesized via the sol–gel process. The dielectric constant, electrical conductivity and loss tangent of our acrylic rubber (AR71)–lead titanate (PT) composite material (AR/PT_8) were 14.15, 2.62 × 10^?7/Ω m, and 0.093, respectively, measured at 27 °C and 1000 Hz. SEM micrographs of composites between the AR71 elastomer and PbTiO₃ showed that the particles were reinforced within the matrix. The electrorheological properties of the AR71/PT composites were investigated as functions of electric field strength from 0 to 2 kV/mm and PbTiO₃ particle volume fraction. The storage modulus increased linearly with particle volume fraction, with or without an electric field. Without an electric field, the particles merely acted as a filler to absorb or store additional stress. With the electric field on, particle‐induced dipole moments were generated, leading to interparticle interactions, and thus a substantial increase in storage modulus. With PbTiO₃ particle volume fractions as small as 10^?4 embedded in the elastomer matrix, the modulus increased by nearly a factor of 2 as the electric field strength varied from 0 to 2 kV/mm. Copyright © 2008 John Wiley & Sons, Ltd.     

Ferroelectric and dielectric behaviour of Bi0.92La0.08FeO3 multiferroic thin films prepared by soft chemistry route

Bi_0.92La_0.08FeO₃ (BLFO) thin films were grown on platine substrates by the soft chemical route. Ferroelectric and dielectric behaviors of BLFO films deposited by spin-coating technique and annealed at 773 K for 2 h in air atmosphere were explained. BLFO thin films obtained presents a rhombohedral structure. The BLFO films present dielectric and ferroelectric behaviors with dielectric permittivity and dielectric loss of approximately 81 and 0.0144 at 1 kHz. The Au/BLFO/Pt capacitor shows a hysteresis loop with remnant polarization of 20.6 μC/cm² and coercive field of 53.88 kV/cm. The polarization switching and the fatigue behavior of the BLFO films were significantly enhanced.     

Physicochemical characterisation of lead titanate solutions applied to the processing of thin films

A new sol-gel method, in which dihydroxy alcohols are used as solvents, is described for the preparation of lead titanate thin films. Infrared spectroscopy and measurements of viscosity are used to study the reaction mechanisms involved in the formation of polymerized solutions. Crack-free lead titanate layers with thickness 0.5 µm are obtained from these solutions, on Pt/TiO₂/Si substrates, by spin-coating and subsequent heat treatments. The formation of the perovskite and the microstructure of these films are monitored by X-ray diffraction, thermogravimetry analysis, differential thermal analysis and scanning electron microscopy.     

Pt／Ti／Si3N4／SiO2／Si基底的多层薄膜制备及拉曼研究

选用三水醋酸铅、乙酰基丙酮酸锆、四异丙氧基钛、乙酰丙酮作初始材料,用同样的方法分别制备了锆钛酸铅（PZT）和钛酸铅（PT）两种固体前驱物．采用改良型的溶胶-凝胶工艺技术,分别在不同的Pt-Ti-Si3N4-SiO2-Si基底上,按照不同的组合方式,制备了三种多层薄膜：PZT、PT／PZT—PZT／PT、PT／PZT／-／PZT／PT．较详细地讨论了薄膜制备的工艺技术,发现当凝胶通过烧结和干燥后变成固态物质时,薄膜内部存在着较大的残余应力,当薄膜在600℃下退火时其内部残余应力可以被减小．通过拉曼衍射和XRD分析,发现PT／PZT—PZT／PT结构的薄膜具有较好的结晶性和较小的残余应力．XRD分析表明,多层混合薄膜的衍射峰是PZT和PT两种薄膜衍射峰的叠加．