Papers by Keyword: Ferroelectric Properties

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Authors: Pichitchai Butnoi, Pratthana Intawin, Ploypailin Yongsiri, Nuttapon Pisitpipathsin, Puttapon Pengpad, Patamas Bintachitt, Kamonpan Pengpat
Abstract: The ferroelectric ceramics with composition of (1-x)Pb(Zr0.52Ti0.48O3 [PZT] – x(Ba0.9Ca0.1)(Ti0.85Zr0.15)O3 [BCZT] (x = 0, 0.04, 0.08 and 0.10 ) have been successfully prepared via two-step mixed oxide method. The material systems of lead zirconate titanate (PZT) and barium calcium zirconate titanate (BCZT) have been intensive studied due to their remarkable properties of high ferroelectric and piezoelectric values. In this work, we are interesting to combine PZT with BCZT system in order to improve the electrical property of the ceramic samples. From the obtained results, it can be confirmed that ferroelectric values are significant increased with the optimum amount of the BCZT.
Authors: Yu Chen Guo, Hui Qing Fan, Jing Shi
Abstract: The perovskite oxide Bi0.5Na0.5MnxTi1-xO3, Bi0.5Na0.5NbxTi1-xO3, Bi0.5Na0.5 (Mn0.5Nb0.5)xTi1-xO3 and Bi0.5Na0.5TiO3 ceramics (x=0.25%) were prepared via the conventional solid state reaction method. The role of Mn as an acceptor, Nb as a donor and (Mn0.5Nb0.5) substitution at B site in BNT lead-free piezoceramics was investigated. The (Mn0.5Nb0.5) substitution led to the inhibited of reduction of Ti4+ to Ti3+ and gave rise to large defect-dipole clusters containing highly localized electrons which should be responsible for the increase of Tc and Td. The ferroelectric properties and field-induced strains were both improved by Mn-acceptor and (Mn0.5Nb0.5) co-doped. The fatigue-resistant properties of Nb doped BNT ceramics were comparable to BNT ceramics, Mn doped ceramics were found to have significantly improved fatigue-resistant properties, while almost no profound fatigue was observed in BNT-MnNb ceramics after switching over 106 cycles at room temperature.
Authors: Min Chang Kuan, Kai Huang Chen, Chien Min Cheng, Chun Cheng Lin, Shih Fang Chen
Abstract: The structure and electrical characteristics of the lead-free Lix(K0.5Na0.5)1-x(Nb0.8Ta0.2)O3 (x=0~0.05) piezoelectric ceramics for the conventional solid-state reaction method and the B-side pre-calcined method were achieved and compared. For the B-side pre-calcined method, the lead-free ceramic material exhibited the excellent electrical and piezoelectric properties. The relative dielectric constant (εr) and loss (tan δ) of the Lix(K0.5Na0.5)1-x(Nb0.8Ta0.2)O3 for x=0.03 using the B-side pre-calcined method were 1223 and 0.021, respectively. In addition, the electromechanical coupling factors (kp) and Curie temperature (Tc) was 48.5 % and 315°C. Finally, the electrical properties of the lead-free Lix(K0.5Na0.5)1-x(Nb0.8Ta0.2)O3(x=0~0.05) homogeneity ceramics improved by the B-side pre-calcined method were also investigated and discussed.
Authors: Tanabat Promjun, Saksit Sukprasong, Ladapak Chumprasert, Athipong Ngamjarurojana
Abstract: Ceramics in the xPb (Zn1/3Nb2/3)O3−(1-x)Pb (Zr1/2Ti1/2)O3 [xPZN–(1-x)PZT] solid solution system are expected to display excellent dielectric, piezoelectric, and ferroelectric properties in compositions close to the morphotropic phase boundary (MPB). The dielectric behavior of ceramics with x = 0.1 − 0.5 has been characterized in order to identify the MPB compositions in this system. Combined with x-ray diffraction analysis, dielectric, piezoelectric and ferroelectric measurements, it was consistently shown that an MPB exists around x = 0.3 in this binary system. When x ≤ 0.2, the tetragonal phase dominates at ambient temperatures. In the range of x ≥ 0.4, the rhombohedral phase dominates.
Authors: Xin Guan, Xiang Yun Deng, Jian Hao, Guang Hao Sun, Chuang Jun Huang
Abstract: Barium calcium titanate (Ba0.96Ca0.04)(Zr0.05Ti0.95)O3 ferroelectric ceramics were prepared by sol–gel technique. The ceramics were sintering at 1290°C-1370°C. X-ray diffraction was employed to investigate the microstructure, and the surface topography was investigated by SEM graphs. The dielectric constant vs temperature was measured by Temperature dielectric spectrometer, and TF Analyzer 2000 measured the ferroelectric properties. It can be found that all the ceramics show pure perovskite structure suggesting that solid solution were formed. SEM showed that the samples uniform in grain size at 1330 °C. Our study revealed that when the sintering temperature is 1330 °C the maximum dielectric constant was 29,600, the maximum piezoelectric coefficient d33 could reach 399pm/V and the remanent polarization (Pr) was 8.3 μc/cm2, respectively.
Authors: Gang Chen, Jie Hao Wei, Xiao Dong Peng, Chun Lin Fu, Wei Cai
Abstract: Sr2-x(Li2/3, Ce1/3)x Nb2O7 (x = 0, 0.05, 0.1, 0.2, 0.3, 0.5) (SLCN) ceramics were prepared by solid-state reaction method. The microstructure, dielectric and ferroelectric properties were investigated. The results show that all ceramics have high relative densities. Li+ and Ce4+ co-doping can promote the grains growing, and improve the dielectric and ferroelectric properties of strontium niobate ceramics. The dielectric constant decreases firstly, and then increases with the increasing of x in Sr2-x(Li2/3, Ce1/3)x Nb2O7, and the sample with x = 0.5 exhibits enhanced dielectric properties (εr ≈ 250, tanδ ≈ 0.02). The remnant polarization (Pr) and coercive electric field (Ec) of SLCN ceramics increase firstly, and then decrease with the increasing of Li+ and Ce4+ content, finally reach the maximum value of remnant polarization (Pr ≈ 0.058μC/cm2, Ec ≈ 6.87 kV/cm ) for x = 0.2.
Authors: Na Na Shao, Xi Yun He, Da Zhi Sun, Bin Xia, Xia Zeng, Wen Xiu Cheng, Ping Sun Qiu, Yu Bai Pan
Abstract: Lead-free EO ceramics have been received increasing attentions from the view point of green environment in recent years. In this study, lead-free Ba6-1.5xLaxTi2Nb8O30 (0≤x≤7%) ceramics were synthesized by the conventional solid state reaction sintering method. The effects of lanthanum doping on the microstructure and electrical properties of Ba6Ti2Nb8O30 (BTN) ceramics were investigated and analyzed. The XRD results revealed that the lanthanum doping changed the BTN lattice parameters slightly. The sample grain size, dielectric constants (1kHz) and the temperature Tm gradually decreased with the increasing of lanthanum doped content. The optimized BLTN ceramic sample with x=4 mol % exhibited a good transparency and excellent electrical properties (Ps=6.41 μC/cm2, Pr=0.77 μC/cm2, and Ec=3.80 kV/cm).
Authors: Xia Zeng, Wen Xiu Cheng, Ping Sun Qiu, Xi Yun He
Abstract: Highly transparent lead lanthanum zirconate titanate (Pb1−xLax)(Zr0.65Ti0.35)1-x/4O3 (x=0.096-0.1) electro-optic ceramics were prepared by the hot pressing method. The ceramics exhibited transparency as high as 67% at 632.8nm (close to the theoretical value). The effects of lanthanum substitution on the phase structure, microstructure, dielectric, ferroelectric, optical and electro-optic properties of PLZT were examined systematically. The XRD results indicated that all the compositions were single perovskite phases, and La substitution decreased the lattice constant and unit-cell volume. The dielectric results showed that the Tmax and εmax decreased with La content increasing. The hysteresis loops showed that the La content reduced saturate polarization (Ps), remnant polarization (Pr) and coercive field (Ec). Moreover, the half-wave voltage and EO coefficient R was enhanced and reduced respectively with increasing La.
Authors: Gang Chen, Xiao Dong Peng, Chun Lin Deng, Chun Lin Fu, Wei Cai, Chun Yan Deng, Xiao Shuang Li
Abstract: The La2Ti2O7+xwt%ZnO(x=0, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5) ceramics were prepared by the conventional solid state reaction method, and effects of ZnO doped on the structure, dielectric and ferroelectric properties were investigated in detail. The X-ray diffraction patterns of La2Ti2O7 ceramics doped by ZnO oxide showed that no second phase exists. The surface morphology is palte-like shape, the grains of La2Ti2O7 ceramics increase with increasing the content of ZnO, and the result is to improve the density of La2Ti2O7 ceramics. The dielectric constant and loss decreases with increasing frequency.When the content of ZnO is more than 0.05wt%, the dielectric constant and loss decreases with the amount of addition of ZnO oxide increasing. The ferroelectric hysteresis loop is not saturable, which is attributed to its large leakage current. The ferroelectric properties improve with the addition of ZnO oxide. .
Authors: Neeraj Kumar, Rabinder Nath
Abstract: The ferroelectric and electrical properties of potassium nitrate (KNO3): polyvinylidene fluoride (PVDF) composite layers prepared by melt press method have been studied. The stability of ferroelectric phase (phase –III) of potassium nitrate (KNO3) in the composite layers at room temperature have been analyzed. The temperature dependence of ferroelectric hysteresis loop (P-E) characteristics have been investigated in the composite layers. The electrical conductivity (σ) and dielectric behaviour of composite layers have been characterized. The conductivity and dielectric variation with temperature during heating and cooling modes has been found to provide the knowledge of phase transition in the composite. The capacitance –-voltage (C-V) and conductance - voltage (G-V) characteristics clearly show the ferroelectric butterfly loop, which is attributed to the features of ferroelectricity in the composite layers at room temperature. The coexistence of ferroelectric phase (phase III) with paraelectric phase (phase II) has also been observed at room temperature in the composite layers during dielectric and conductivity measurements.
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