Papers by Keyword: Lead Titanate

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Authors: Minoru Tamada, Yuji Noguchi, Masaru Miyayama
Abstract: Single crystals of PbTiO3 (PT) were grown by a self flux method, and effects of lattice defects on the leakage current properties were investigated. While PT crystals annealed in air at 700 oC showed a leakage current density of the order of 10-5 A/cm2, annealing under a high oxygen partial pressure of 35 MPa increased leakage current density to 10-4 A/cm2. The increase in leakage current by the oxidation treatment provides direct evidence that electron hole is a detrimental carrier for the leakage current property of PT at room temperature. The vacancies of Pb are suggested to act as an electron acceptor for generating electron holes.
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Authors: Nurbaya Zainal, Mohd Hafiz Wahid, Mohammad Rusop
Abstract: Performance of lead titanate, (PbTiO3) thin films have been successfully investigated on microstructural properties, I-V characteristic, dielectric properties, and ferroelectric properties. PbTiO3 offers variety of application as transducer, ferroelectric random access memory, transistor, high performance capacitor, sensor, and many more due to its ferroelectric behavior. Preparation of the films are often discussed in order to improve the structural properties, like existence of grain boundaries, particle uniformity, presents of microcrack films, porosities, and many more. Yet, researchers still prepare PbTiO3 thin films at high crystallization temperature, certainly above than 600 ̊C to obtain single crystal perovskite structure that would be the reason to gain high spontaneous polarization behavior. Although this will results to high dielectric constant value, the chances that leads to high leakage current is a major failure in device performance. Thus, preparation the thin films at low annealing temperature quite an essential study which is more preferable deposited on low-cost soda lime glass. The study focuses on low annealing temperature of PbTiO3 thin films through sol-gel spin coating method and undergo for dielectric and I-V measurements.
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Authors: S. Sidorkin, L.P. Nesterenko, I.A. Bocharova, G.L. Smirnov, V.A. Sidorkin, S.V. Ryabtsev, A.L. Smirnov
Abstract: Lead titanate thin films were obtained by plasma-enhanced magnetron sputtering. Synthesized films demonstrate high temperature stability, relatively narrow maximum at temperature of phase transition for ε (T ) dependence, great dielectric constant value near the Curie point, saturated hysteresis loops, and relaxation character for dispersion of dielectric permittivity similar to bulk samples.
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Authors: W. Tangkawsakul, Panadda Sittiketkron, Theerachai Bongkarn
Abstract: In this work, we studied the effect of excess PbO on crystal structure, microstructure and phase transition of lead titanate (PT). PT was prepared via a mixed oxide method with various PbO levels (0, 1, 3 and 5 wt.%). The raw materials were calcined at 750 oC for 2 h and sintered at 1225 oC for 2 h. The characteristics of PT were analyzed by a X-ray diffractometer (XRD), scanning electron microscopy (SEM) and differential scanning calorimeter (DSC). It was found that calcined powders and sintered ceramics indexed in a tetragonal structure. For PT powders, the impurity phases of lead oxide (PbO) and lead dioxide (PbO2) were detected in 3 and 5 wt.% of excess PbO samples, but they were not detected in all sintered ceramic samples. The increase of excess PbO levels resulted in a decreased c/a ratio in both calcined powders and sintered ceramics. Average particle sizes increased from 0.64 to 4.24 µm when excess PbO levels increased from 0 to 5 wt.%. It was also clearly seen that the liquid phase of the sintering process was obtained in the PT calcined powders which had an excess of PbO. The DSC result indicated that the phase transition temperature, from a ferroelectric to a paraelectric phase with a high PbO content (5 wt.%), was higher than those with low PbO contents (0, 1 and 3 wt.%).
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Authors: L.W. Tang, Pi Yi Du, Wen Jian Weng, Gao Rong Han
Abstract: Silver dispersed lead titanate films were prepared with different Pb/Ti ratio precursors. The influence of lead excess in precursor on the formation and dielectric properties of silver-dispersed lead titanate film was investigated. Firstly, Pb excess in precursor will eliminate the formation of pyrochlore PbTi3O7 and increase c/a ratio of perovskite PbTiO3. Secondly, excessive Pb will react with silver, and they can produce volatile product, which evaporate during heat treatment process. The volatility of the reaction product varies with the increase in lead excess. When lead excess is low (Pb/Ti=1.1), volatility of reaction product is high. At this time, only small amount of silver remain in the film. The remanent silver aggregate to form small silver particles. When lead excess is high (Pb/Ti=1.2 and Pb/Ti=1.3), volatility of reaction product gradually becomes poor. At this time, the content of remanent silver in the film increase with the increase in lead excess. Compared with the film prepared with low Pb/Ti ratio, the dispersive degree of silver in film prepared with high Pb/Ti ratio is higher. Due to the decrease of remanent silver content in the film, dielectric constant and dissipation factor both decrease when Pb/Ti initially increase from 1 to 1.1. And after that, dielectric constant and dissipation factor both increase with the addition of excessive Pb in precursor, due to the increase in the content and dispersion degree of silver, and increase in c/a ratio of PbTiO3 lattice with the addition of excess Pb. The film prepared with appropriate excessive lead (Pb/Ti=1.3) precursor expresses higher dielectric constant and lower dissipation factor than the film prepared with stoichiometric Pb/Ti ratio.
107
Authors: Nurbaya Zainal, Habibah Zulkefle, Mohamad Rusop
Abstract: Lead titanate thin films were successfully prepared using a simple sol-gel method. In the present study extra Pb excess was not taken into consideration in such a way that the ratio of Pb:Ti is 1:1. Different molar concentration (0.1, 0.2, 0.3, 0.4, and 0.5) involved in this study and it was found that the solutions increased in acidic level by the increment of molar concentration that being measured by pH and conductivity meter (JENWAY-3540). It also indicated that the solutions were electrically resistive at low concentration which might due to the existence of lead and oxygen ionic bonding. The solutions were then deposited onto cleaned glass substrate by spin coating technique indeed to have better thin film homogeneity at room temperature. The prepared thin films were characterized on electrical property considering the resistivity measured by solar simulator (BUKOH KEIKI EP-2000). After that structural and physical property of thin films were observed by atomic force microscopy (Park System, XE-100).
379
Authors: Panadda Sittiketkron, S. Sukkho, Theerachai Bongkarn
Abstract: In this work, the effect of ZrO2 doping on the properties of PbTiO3 ceramics was investigated. PbTiO3 powders were prepared via a mixed oxide method with a calcination temperature of 750 °C for 2 h. The various amounts of ZrO2, between 0 and 2 wt.%, were added to the calcined powders to decrease the c/a ratio. The mixed powders were sintered at 1225 °C for 2 h. The samples were characterized using X–ray diffractrometer (XRD), scanning electron microscopy (SEM) and differential scanning calorimeter (DSC). It was showed that the ZrO2 phase was not detected in all of the powder and ceramic samples. The highest density in the ceramics was found in the sample with 0.5 wt.% of ZrO2. The average grain size slightly increased with the increase of ZrO2. The phase transition temperature from tetragonal ferroelectric to cubic paraelectric was about 465 to 466 °C for all sintered samples.
169
Authors: De Sheng Fu, Hisao Suzuki, Kenji Ishikawa
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Authors: Takashi Nishida, Koichi Kubo, Masahiro Echizen, Hiroaki Takeda, Kiyoshi Uchiyama, Tadashi Shiosaki
Abstract: In order to perform the growth position control, PbTiO3 (x=0) (PTO) nanocrystals were deposited on atomically flat and non-atomically flat -Al2O3 substrates by RF magnetron sputtering. The atomically flat substrates with atomic steps and terrace are expected to induce the lateral growth along a terrace between the surface steps. In the case of the atomically flat, the nanocrystals got lined up along the atomic steps, and uniform nanocrystals were obtained on surface in same pitch.
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