[Show abstract][Hide abstract]ABSTRACT: The single phase (1 - x)PbTiO3 - xBi(Ni1/2Ti1/2)O-3 thin films were synthesized on Pt/Fi/SiO2/Si substrate at 600 degrees C by a chemical solution deposition route. The present films exhibit homogeneous and crackfree microstructure with low porosity. The surface roughness decreases from 5.56 nm to 1.62 nm with solubility. The remanent polarization monotonously decreases with the dopant Bi(Ni1/2Ti1/2)O-3 increase. The leakage current desity increases when the solubility increases. O K-edge X-ray absorption spectroscopy and valence-band edge X-ray photoelectron spectroscopy were used to study the electronic structure. The results indicated that the change of ferroelectricity might be ascribed to the hybridizations between O 2p and Pb 6s and Ti 3d orbitals. The ferromagnetic behaviors were also observed in the thin films and saturated magnetization raises monotonously with the Ni solubility due to enhanced superexchange interaction. Magnetoelectic effects increases with dopant Bi(Ni1/2Ti1/2)O-3 increase.
[Show abstract][Hide abstract]ABSTRACT: Lead-free potassium sodium niobate-based piezoelectric ceramics (1−y)(Na0.5−0.5xK0.5−0.5xLix)NbO3−yBiScO3 ( y=0.01, x=0–0.06) have been prepared by an ordinary sintering process. The XRD analysis showed that the structure changes from orthorhombic to tetragonal with the increase of x (at y=0.01, abbreviated as KNNBSL100x). At room temperature, the polymorphic phase transition from the orthorhombic to the tetragonal phase was identified at approximately 0.02≤x≤0.04. The piezoelectric and ferroelectric properties were significantly enhanced. The temperature dependences of the relative permittivity revealed that the Curie temperature was increased with the addition of LiNbO3. These solid solution ceramics are promising as potential lead-free candidate materials.
Article · May 2009 · Journal of the American Ceramic Society
[Show abstract][Hide abstract]ABSTRACT: The compounds (1−x)PbTiO3–xBi(Mg,Ti)1/2O3 (x = 0–0.7) were prepared in order to hunt for low thermal expansion piezoceramics, in particular for zero thermal expansion over a wide temperature range. The negative thermal expansion of PbTiO3 was much weakened by forming a solid solution with Bi(Mg,Ti)1/2O3. Solutions of (1−x)PbTiO3–xBi(Mg,Ti)1/2O3 with x = 0.2 and x = 0.4 exhibited zero thermal expansion covering a wide temperature range (from RT to about 500 °C). The (1−x)PbTiO3–xBi(Mg,Ti)1/2O3 ceramics had high density and their mechanical performances were satisfactory with high fracture toughness. The promising applications of the zero thermal expansion materials (1−x)PbTiO3–xBi(Mg,Ti)1/2O3 are due to its high piezoelectric d33, controllable thermal expansion, and high thermal stability.
Article · Mar 2009 · Journal of Materials Chemistry
[Show abstract][Hide abstract]ABSTRACT: 0.96(Na,K)(Nb0.9Ta0.1)O3–0.04LiSbO3 powders in the orthorhombic phase were synthesized in the molten salt KCl at a low temperature 800 °C. It was revealed that K+ in the molten salt tended to substitute Na+ in the A-sites and the final product 0.96(Na0.29K0.71)(Nb0.9Ta0.1)O3–0.04LiSbO3 was synthesized from the nominal composition 0.96(Na0.5K0.5)(Nb0.9Ta0.1)O3–0.04LiSbO3. The dense ceramics under pressureless were obtained by sintering in the air. The ceramics exhibited high piezoelectric constant d33 of 239 pC/N and good remnant polarization Pr of 30.79 μC/cm2 with coercive electric field Ec of 2.01 kV/mm. And leakage current was reduced by muffling the ceramics with the as-prepared powders during the sintering process.
Full-text Article · Mar 2009 · Journal of Alloys and Compounds
[Show abstract][Hide abstract]ABSTRACT: Lead-free potassium sodium niobate-based piezoelectric ceramics (1−x)(Na0.5K0.5)NbO3–xBiScO3 (KNN–BS) (x=0∼0.05) have been prepared by an ordinary sintering process. Single perovskite phase of KNN–BS exhibits an orthorhombic symmetry at x<0.015 and pseudocubic symmetry at x>0.02, separating by a MPB at 0.015≤x≤0.02. Piezoelectric and ferroelectric properties are significantly enhanced in the MPB, which are as follows: piezoelectric constant d33=203 pC/N, planar coupling coefficient kp=0.36, remnant polarization Pr=24.4 μC/cm2. These solid solution ceramics look promising as a potential lead-free candidate materials.
Article · Dec 2008 · Journal of the American Ceramic Society
[Show abstract][Hide abstract]ABSTRACT: Lead-free piezoelectric ceramics (1−x)(Na0.5K0.5)NbO3-xBiFeO3 (x=0~0.07) were synthesized by the solid-state reaction. Differential scanning calorimetry (DSC) measurements revealed that an increase in the amount of BiFeO3 dopant resulted in a decrease in the orthorhombic-tetragonal and tetragonal-cubic phase transition temperature of the material. One percent BiFeO3 additive suppressed grain growth, which not only benefits the sintering of ceramics but also enhances the piezoelectric and ferroelectric properties, where d33=145pC/N, kp=0.31, Qm=80, Pr=11.3 μC cm−2 and Ec=16.5 kV cm−1. As xBF>0.01, both piezoelectric and ferroelectric properties decreased rapidly with an increasing amount of dopant.
Full-text Article · Jun 2008 · Science and Technology of Advanced Materials
[Show abstract][Hide abstract]ABSTRACT: Hexagonal ilmenite-type (Zn1-xMnx)TiO3 (0 <= X <= 0.9) ceramic powders were synthesized by a sol-gel route including the Pechini process with heat treatments at 600 degrees C for 3 h and 800 degrees C for 6 h. The thermal stability of ZnTiO3 dielectric ceramics was improved (> 1200 degrees C) by doping manganese. The dielectric constant of (Zn1-x,Mn-x)TiO3 ceramic was higher than those of (Zn, M)TiO3 (M = Co, Ni, etc.), increased with the amount of manganese in the range of 0 <= x < 0.7 then decreased after the maximum point at x = 0.7 in the same frequency. Both the dielectric loss tangent and the dielectric constant decreased with increasing the measured frequencies. The value of dielectric loss tangent was relatively high because of magnetoresistive effect of manganese. (c) 2007 Elsevier B.V. All rights reserved.
Article · May 2008 · Journal of Alloys and Compounds
[Show abstract][Hide abstract]ABSTRACT: Well monodispersed and large-scaled Pr-doped ceria nanorods were prepared via a high-temperature precipitation and low-temperature aging route without further sintering. X-ray diffraction, transmission electron microscopy and selected-area electron diffraction indicated that the as-prepared ceria nanorods had a cubic fluorite structure and the morphologies of the products were uniform, being ∼30 nm in diameter and ∼400 nm in length. The physisorption experiments showed a high specific surface area of Pr-doped ceria nanorods.
[Show abstract][Hide abstract]ABSTRACT: A facile molten salt synthesis route was developed to prepare ZnTiO3 ceramic powders with simple oxides ZnO and TiO2 using sodium and potassium chloride eutectic salts as flux. The role of calcination temperature and time and the amount of salt addition to ZnTiO3 formation was investigated by thermogravimetry-differential thermal analysis, X-ray diffraction and Fourier transformation-infrared spectroscopy measurements. Pure hexagonal phase of ZnTiO3 could be obtained from the mixture of the simple oxides and the chlorides (50 mol% KCl, 20 times to oxides in molar ratio) heating at 800°C for 6 h. The scanning electron microscopy images revealed the products were hexagonal sheets of about 1–3 μm size. Increasing the amount of salt aids in reducing the crystal sizes of final ceramic powders because of diluting the solution.
Article · Mar 2006 · Journal of the American Ceramic Society
[Show abstract][Hide abstract]ABSTRACT: A multi-component substitution of Co and Ni was incorporated into ZnTiO3 to form pure hexagonal Zn1−x(Co1/2Ni1/2)xTiO3 (x=0,0.8,0.9,1.0) dielectric ceramic powders by a modified sol–gel route, following heat treatments at 600°C for 3 h and at 800°C for 6 h. Differential scanning calorimetry measurements revealed that the order of increasing thermal stability of solid solution compound Zn1−x(Co1/2Ni1/2)xTiO3 was ZnTiO3 (945°C), Zn0.1Ni0.9TiO3 (1346°C), Zn0.1(Co1/2Ni1/2)0.9TiO3 (1390°C), and Zn0.1Co0.9TiO3 (>1400°C). Both the dielectric constant and loss tangent reached a maximum at x=0.8 and then decreased with solubility, x, and measurement frequency.
Article · Mar 2006 · Journal of the American Ceramic Society