Fabrication and optical properties of Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3) thin films on Si substrates using the PLD method.

Epitaxial 0.67Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3)-0.33PbTiO(3) (PMN-PT) thin films with electro-optic effects were fabricated on (PMN-PT) thin films with electro-optic effects were fabricated on (La0(0.5)Sr0(0.5))CoO(3) (LSCO)/CeO(2)/YSZ-buffered Si(001) substrates using double-pulse excitation pulsed laser deposition (PLD) method with a mask placed between the target and the substrate. Epitaxial growth of PMN-PT thin films was undertaken using the two-step growth method of PMN-PT film. The PMN-PT seed layer was deposited at 500 degrees C on the LSCO/CeO(2)/YSZ/Si, which temperature was the same as that used for LSCO deposition. The PMN-PT thin films were deposited on the PMN-PT seed layer at 600 degrees C, which enables growth of high-crystallinity PMN-PT films with smooth surfaces. We obtained optimum fabrication conditions of PMNPT film with micrometer-order thickness. Resultant films showed high crystallinity with full width at half maximum (FWHM) = 0.73 deg and 1.6 mum thickness. Electro-optic properties and the refractive index value were measured at 633 nm wavelength using the prism coupling method. The obtained refractive index was 2.59. The electro-optic coefficients r(13) and r(33) were determined by applying the electrical field between a semitransparent, thin top electrode of Pt and a bottom LSCO electrode. The electro-optic coefficient was r(13) = 17 pm/V at transverse electric field (TE) mode and r(33) = 55 pm/V at transverse magnetic field (TM) mode.     

Ferroelectric BiFeO3-PbTiO3 thin films on Pt/Si substrates

In this work we report on the preparation and properties of bismuth ferrite lead titanate films [(1- x)BiFeO(3-x)PbTiO3] with tetragonal compositions (x = 0.8 and 0.7) and compare them with compositions close to the morphotropic phase boundary (MPB; x = 0.4 and 0.3). The films were prepared by pulsed laser deposition on Pt/Si substrates, and exhibited a dense columnar grain growth. X-ray diffraction analysis revealed that the films have a perovskite structure with a preferred (111) texture. The dielectric properties, polarization-field hysteresis, and leakage current behavior of the films is also reported. For MPB compositions, the films exhibited remanent polarizations with 2Pr up to 100 microC cm(-2) and E(c) approximately 185 kV cm(-1) under a maximum applied field of 500 kV cm(-1), while the tetragonal compositions exhibited 2Pr values in the range of 45-52 microC cm(-2) with a coercive field E(c) approximately 118 kV (-1).     

Intermediate Temperature Sintering of La-Modified Pb(Zn1/3Nb2/3)O3-PbZrO3-PbTiO3 Piezoelectric Ceramics

In order to realize the co-firing with Ag/Pd electrodes in multilayer devices, Pb(Zn1/3Nb2/3)1-,-yZrxTiyO3(0.25＜x＜0.35, 0.25＜y＜0.35) piezoelectric ceramics (hereafter designated PZN-PZT)modified by La2O3 has been prepared by conventional technique with sintering temperature from 1100℃ to 1140℃. X-ray diffraction patterns demonstrated that pure perovskite phase was obtained. Secondary electron image (SEI) showed that crystalline grains in ceramics were well grown. d33 of manufactured sample was as high as 560×10-12C/N. kp was about 0.61 and tgδabout 30×10-3. The existence of liquid phase examined by electron diffraction in PZN-PZT sample is beneficial to sintering of the ceramic.     

Investigation into the growth and electromechanical properties of Pb(Mg1/3Nb2/3)O3 thin films

Pulsed laser deposition (PLD) has been used to fabricate relaxor thin films and thin film capacitors based on the Pb(Mg_1/3Nb_2/3)O₃ system. Best capacitor structures show dielectric constants (_r) of 1000 and losses (tan ) 0.02 at 1 kHz at 300 K. Electromechanical investigations show that tensile longitudinal strains of up to 0.2% can be achieved in these films.     

Temperature stable dielectric properties for Pb(Mg1/3Nb2/3)O3-BaTiO3-PbTiO3 system ceramics

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.     

Pb(Mg1/3Nb2/3)O3-PbTiO3晶体组分对结构与性能的影响

用熔体Modified Brdgman法生长出尺寸直径40 mm长度80 mm的弛豫铁电单晶PMNT90/10,表明该方法不仅适合在准同型相界(MPB)附近生长PMNT单晶,也适合生长PT含量很低的PMNT单晶.在生长出的PMNT90/10晶体中,铁电相与顺电相两相共存,并呈现亚微畴结构特征.随着晶体组分由PMN组元变化到MPB组分附近,PMNT的电畴结构呈现微畴-亚微畴-不规则宏畴-规则宏畴演化系列,而介电弛豫特性则逐步弱化.PMNT固熔体的电学性能依赖于晶体组分,(001)切型PMNT90/10晶体的压电常数d33约80 pC/N,显著低于MPB附近组分,但其介电常数ε达到12600,明显高于后者.     

Perovskite formation and dielectric responses in Pb(Zn1/3Nb2/3)O3-modified Pb(Zn1/3Ta2/3)O3-PbTiO3 ceramics

Pb(Zn_1/3Ta_2/3)O₃-PbTiO₃ ceramic compositions were modified by the introduction of Nb to the octahedral lattice sites. Resultant tendencies in the perovskite formation and dielectric properties were examined. System powders were prepared using a B-site precursor method. Developed structures and lattice parameters of the system compositions were investigated by powder X-ray diffractometry, from which the parameter of a hypothetical perovskite Pb(Zn_1/3Ta_2/3)O₃ is proposed. Weak-field low-frequency dielectric responses of the system ceramics were measured.     

在金属基片上以LNO为过渡层制备Pb(Zr0.53Ti0.47)O3薄膜的电性能

采用溶胶-凝胶法和快速热处理工艺,分别以不锈钢(SS)和镍合金(NC)为基片,成功制备了表面均匀、无裂纹的锆钛酸铅(Pb(Zn0.53Ti0.47)O3,简写为PZT)薄膜.为了缓解金属基片与PZT薄膜之间由于晶格常数和热膨胀系数不同所造成的不匹配状态,引入了镍酸镧(LaNiO3,简写为LNO)薄膜作为过渡层.XRD和SEM结果表明,经过600℃下30min的晶化,PZT薄膜已经由无定型转化为钙钛矿相.以LNO为过渡层,在NC金属基片上制备的PZT薄膜具有较高的介电常数和较低的损耗(1kHz下ε=717,tanδ=0.08),较低的漏电流(50kV/cm下J=2.6×10-7A/cm2)以及较好的铁电性能(+Pr=90μC/cm2,-Pr=14 μC/cm2,Ec=32.5kV/cm).同时,在SS基片上,通过引入LNO过渡层,制备的PZT薄膜也具有比较好的性能.     

Processing and properties of Pb(Mg1/3Nb2/3)O3-PbZrO3-PbTiO3 ceramic relaxors

The shrinkage phenomenon during the reaction-sintering of PMN-PZT from low-temperature pre-reacted 3PbO + MgNb₂O₆ + PZT powder mixtures has been studied. It was assumed that the pre-reaction treatment leads to the formation of a pyrochlore phase containing very active MgO small particles, and that the strong shrinkage occurring up to 800 °C took place by the diffusion of Mg²⁺ cations into the pyrochlore phase particles, thus controlling the reaction-sintering shrinkage phenomenon. Above that temperature the densification was enhanced by a liquid-phase sintering process. The ceramics sintered at 1050 °C for 2 h showed 96% of the theoretical density, and the dielectric constant of such a sintered ceramic showed a maximum value of 17 000 at 1 kHz. It was also found that the dielectric constant decreased with increasing grain size. Although the role of PZT in enhancing the dielectric constant of otherwise low-purity PMN ceramics is not clear, the increase in K is assumed to be a solid-solution effect. The presence of impurities and the PbO stoichiometry could be influencing the not too high dielectric constant value of PMN-PZT ceramics.     

Ferroelectric and dielectric properties of ferroelectromagnet Pb(Fe1/2Nb1/2)O3 ceramics and thin films

The ferroelectric and dielectric properties of ferroelectromagnet Pb(Fe_1/2Nb_1/2)O₃ (PFN) ceramics and thin films prepared by pulsed laser deposition (PLD) have been investigated systematically. PFN ceramics experienced a para-ferroelectric transition and a para-antiferromagnetic transition at 380 K and 145 K, respectively. At room temperature, it has an electrical remnant polarization of 11.5 C/cm² and a coercive field of 4.04 kV/cm. The dielectric behaviors show characteristics of diffusive phase transition at a wide temperature range around 380 K. Anomalies in the dielectric constant and loss tangent have been observed near the Neel temperature of 145 K, indicating a coupling between the ferroelectric and antiferromagnetic orders in PFN ceramics. At room temperature, the PFN films exhibited a remnant electric polarization of 7.4 C/cm², a coercive field of 10.5 kV/cm, and a dielectric constant of 486 at frequency of 10 kHz, indicating their potential applications in memory devices.     

三元陶瓷Pb(In1/2Nb1/2)O3-Pb(Ni1/3Nb2/3)O3-PbTiO3准同型相界附近组分的介电、铁电和压电性能

铅基复合钙钛矿铁电材料广泛应用于机电传感器、致动器和换能器。二元铁电固溶体Pb(Ni_1/3Nb_2/3)O₃- PbTiO₃(PNN-PT)由于其在准同型相界(MPB)区域具有优异的压电、介电性能而备受关注。然而较大的介电损耗和较低的居里温度限制了其在高温高功率器件方面的应用。本研究通过引入Pb(In_1/2Nb_1/2)O₃ (PIN)作为第三组元改善PNN-PT的电学性能, 提高其居里温度; 通过两步法合成了MPB区域的三元铁电陶瓷Pb(In_1/2Nb_1/2)O₃- Pb(Ni_1/3Nb_2/3)O₃-PbTiO₃ (PIN-PNN-PT), 研究了其结构、介电、铁电和压电性能。制备的所有组分陶瓷具有纯的钙钛矿结构。随着PT含量的增加, 陶瓷结构从三方相转变为四方相。通过XRD分析得到了室温下PIN-PNN-PT体系的MPB相图。体系的居里温度由于PIN的加入得到了很大的提高, 更重要的是PIN的引入降低了PNN-PT体系的介电损耗和电导。MPB处的组分展现出了优异的电学性能, 室温下, 性能最优组分为0.30PIN-0.33PNN-0.37PT: d₃₃=417 pC/N, T_C=200 ℃, ε′= 3206, tanδ=0.033, P_r=33.5 μC/cm², E_C=14.1 kV/cm。引入PNN-PT的PIN第三组元使得体系的居里温度和压电性得到提高的同时降低了的介电损耗和电导率, 因此, PIN-PNN-PT三元铁电陶瓷在高温高功率换能器等方面具备一定的应用潜力。     

The substitution-site of Cd2+ in Pb(Ni1/3Nb2/3)O3-PbZrO3-PbTiO3 ceramics

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.     

Structure and electrical properties of (111)-oriented Pb(Mg1/3Nb2/3)O3-PbZrO3-PbTiO3 thin film for ultra-high-frequency transducer applications

Ternary lead magnesium niobate-lead zirconate titanate system 0.4Pb(Mg(1/3)Nb(2/3))O(3)-0.25PbZrO(3)-0.35PbTiO(3) (40PMN-25PZ-35PT) thin film with a thickness of 1.5 μm was grown on Pt(111)/Ti/SiO(2)/Si substrate via chemical solution deposition. X-ray diffraction and transmission electron microscopy results suggested the film obtained was highly (111)-oriented. The remanent polarization and coercive electric field of the film were found to be 25.5 μC/cm(2) and 51 kV/cm, respectively. In addition, at 1 kHz, the dielectric constant was measured to be 1960 and the dielectric loss 0.036. The film was observed to undergo a diffuse ferroelectric-to-paraelectric phase transition at around 209°C. The leakage current appeared to depend on the voltage polarity. If the Au electrode was biased positively, the leakage current was dominated by the Schottky emission mechanism. When the Pt electrode was biased positively, the conduction current curve showed an ohmic behavior at a low electric field and space-charge-limited current characteristics at a high electric field.     

Time dependence of dielectric constants of Pb(Mg1/3Nb2/3)O3-BaTiO3-PbTiO3 ferroelectric ceramics for X7R MLCs

The isothermal ageing behaviour of Pb(Mg_1/3Nb_2/3)O₃-BaTiO₃-PbTiO₃ ceramics, promising high dielectric (ε_25°C = 4574) materials for X7R multilayer ceramic capacitors (MLCs) was studied over a wide range of frequencies. During ageing, the dielectric constants and loss tangents decreased linearly with the logarithm of ageing time. The ageing rates were evidently influenced by the test frequencies. The maximum value, within the range 0.1 to 1000 kHz, was about 1.7% per decade (time) and meets the corresponding ageing specifications for X7R ceramic dielectrics. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of high pressure on the dielectric properties of relaxor compositions [Pb(Fe1/2Nb1/2)O3]1-x-y-[Pb(Zn1/3Nb2/3)O3]x- [BaTiO3]y

Abstracts are not published in this journal     

Pb(Ni1/3Nb2/3)O3-PbTiO3系统准同型相界附近的介电异常

用两步合成法制备了(1-x)Pb(Ni1/3Nb2/3)O3-xPbTiO3(x=0.300.40)陶瓷,对其相结构和介电性能进行了研究. XRD分析表明,准同型相界在PT含量x=0.340.38范围内. 介电性能研究结果表明,组成在准同型相界处的试样, 其介电常数呈现最大值.同时还发现,准同型相界处的陶瓷出现介电双峰,其中一个为弛豫型?铁电相向顺电相转变的相变峰;另一个介电峰处于130150C的高温区, 可能是由镍离子变价、相结构变化等缺陷引起的松弛极化产生的.