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In our previous work, we developed lead-free potassium sodium niobate-based textured ceramics with a piezoelectric response (d33*) of 505 pm/V and superior thermal stabilities. However, the dielectric loss of the ceramics is 3.5% at 1 kHz which is higher than the PZT-based ceramics. To solve this problem, MnO2 was introduced into the KNLN-BZ-BNT ceramics in this work. It is found that the introduction of MnO2 does not affect the crystalline phase nor grain size. In addition, the effect of MnO2 of less than 2.0% on the texture degree is insignificant. The 0.5% and 1.0% MnO2 modified samples show similar electrical properties and thermal stability as the one without MnO2. The addition of MnO2 can reduce the dielectric loss. Compared to the ceramic with 0.5% MnO2 addition, the 1.0% MnO2-added KNLN-BZ-BNT ceramic possesses a better performance. [ABSTRACT FROM AUTHOR]

A novel relaxor solid solution of (1-x)Pb(Mg1/3Nb2/3)O3-xPb(Cd1/3Nb2/3)O3 [(1-x)PMN-xPCN] is synthesized by the solid-state reaction method. The crystal structure, electric properties and relaxor behavior are investigated. This system exhibits an average cubic perovskite structure at room temperature. The cation ordering, which is hardly detectable in the canonical PMN by laboratory-based high-resolution X-ray diffraction, is clearly evidenced in this solid solution. The relaxor behavior of the solid solution is found to be enhanced in the (1-x)PMN-xPCN solid solution compared with PMN. The enhanced relaxor behavior is attributed to be formation of complex ordered and disordered structures, which leads to a broader distribution of the size and dynamics of local polar heterogeneities. [ABSTRACT FROM AUTHOR]

Ceramics of a perovskite solid solution, (1-x)PbTiO3-xDyFeO3, with x ≤ 0.4 are synthesized using the solid-state reaction method. The linear magnetization vs. magnetic field relation as well as the Curie-Weiss type temperature dependence of magnetic susceptibility observed in compositions with x ≤ 0.2 suggests the paramagnetic nature. When x ≥ 0.25, the weak ferromagnetic state can be induced. Moreover, the Dy3+ ions are enrolled into the superexchange coupling together with Fe3+ ions at low temperature, giving rise to magnetic phase transitions upon cooling in compositions with x = 0.4. Furthermore, the paraelectric subsystem is proposed to exist in weak ferromagnetic compositions. [ABSTRACT FROM AUTHOR]

Ceramics of a novel solid solution system, (1-x)Pb(Zr0.52Ti0.48)O3-xBi(Zn2/3Nb1/3)O3 [(1-x)PZT-xBZN], with compositions near the morphotropic phase boundary (MPB), are synthesized by solid-state reaction method and investigated by X-ray diffraction, dielectric spectroscopy, and ferroelectric and piezoelectric measurements. It is found that the increasing amount of Bi(Zn2/3Nb1/3)O3 (BZN) changes the structure of this system from the tetragonal symmetry to the MPB. The remnant polarization, coercive field and electromechanical properties are significantly enhanced compared with pure PZT ceramics, which is correlated with the MPB feature of the (1-x)PZT-xBZN system. With the increase of BZN content, a gradually diffuse phase transformation with monotonically decreasing Curie temperature and increasing dielectric loss is found. [ABSTRACT FROM AUTHOR]

Mn1.56Co0.96Ni0.48O4ceramics were prepared by co-precipitation method with two different cooling rates. The structures and properties were characterized by using X-ray diffraction, scanningelectron microscope, atomic force microscope, spectroscopic ellipsometry and optical aging test.The optical constants of two samples are close to each other and have consistent variation trend in the wavelength range of 300 ∼ 1000 nm. However, the refractive indexnand extinction coefficientkvary after accelerated aging testespecially the quenched sample. [ABSTRACT FROM AUTHOR]

A solid solution system of novel ferroelectric (1−x)PbTiO3-xDyFeO3ceramics with 0 ≤x≤ 0.50 has been synthesized using the solid state reaction method. The X-ray diffraction data at room temperature indicate a composition-induced structural transition from the tetragonal P4mm phase for 0 ≤x< 0.25 to the cubic Pm-3m phase forx≥ 0.25. Both the unit cell volume and the tetragonality gradually decrease with increasingx. The grain size of the ceramics is found by Scanning Electron Microscopy to increase first and then decrease with increasingx. The Curie point moves to low temperatures with increasing DyFeO3concentration and a composition-induced crossover from a normal ferroelectric phase to a ferroelectric state with diffuse phase transition has been observed. Two Havriliak-Negami relaxation processes and a significant contribution from dc conductance were found at high temperature above the temperature of dielectric maximum,Tm. The room temperature ferroelectric polarization shows a decrease with the increase ofx. A partial phase diagram of the solid solution system is constructed based on the dielectric, ferroelectric and structural analyses. [ABSTRACT FROM AUTHOR]

In this work, the relationships between phase development and the properties of a new relaxor based ferroelectric (1-x)Pb(Mg1/3Nb2/3)0.9Ti0.1O3-xBi0.5(Na0.74K0.26)0.5TiO3ceramics (whenx= 0.0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1.0 mole fraction) was studied. The pseudo-cubic structure was observed in the ceramics withx≤ 0.7 mole fraction. The rhombohedral and tetragonal phases were found to coexist whenxincreased to 0.9, which transformed into the single tetragonal phase whenxincreased to 1.0. The dielectric constant measured at room temperature decreased with increasingx. The remnant polarization and piezoelectric constant of the ceramics significantly increased whenxincreased to 0.9 and 1.0. [ABSTRACT FROM AUTHOR]

The use of piezoelectric films in high-frequency ultrasonic transducers requires thick, dense, and crack-free films with excellent piezoelectric properties. In this work, Bi0.5Na0.5TiO3(abbreviated to BNT) 0-3 composite lead-free ferroelectric thick films have been successfully prepared by a modified 0-3 composite technique. The BNT fine ceramic powders were dispersed in a sol-gel solution of the same composition to form a uniform slurry, which was deposited on (111) Pt/TiO2/SiO2/Si substrates using spin-coating and then annealed at 700°C. The morphology, microstructure, dielectric properties, ferroelectric properties and leakage current densities of BNT composite thick films have been investigated. BNT ceramic powders sintered at a series of temperatures were used to prepare the thick films. X-ray diffraction analysis indicates that the BNT 0-3 composite thick films exhibit a pure perovskite structure. The electrical properties of the composite films depend strongly on the sintering temperature of BNT ceramic powders. [ABSTRACT FROM PUBLISHER]

Piezoelectric polymers have been for the fabrication of acoustic wave biosensors due to their light weight, low cost, and ease to form different shapes. This paper presents the design and resonance behavior of polyvinylidene fluoride (PVDF) diaphragms for biosensor applications. The phase spectra of the diaphragms were measured to determine the resonance behavior. The influence of boundary condition, excitation voltage and film thickness on the resonance behavior are discussed. After immobilizing the biological probe on gold surface, the diaphragms can be used for detecting target bio-molecules. [ABSTRACT FROM AUTHOR]

In this paper, we report observation and study of transformation of the vibration shapes in resonances of micromachined piezoelectric circular membrane. Micromachined piezoelectric zinc oxide circular membrane was fabricated and the vibration shapes of the membrane at different frequencies were measured by a scanning Mach-Zehnder interferometer. The finite element analysis with a commercial software ANSYS was performed to study the vibration characteristics of the circular membrane. The result shows that the transformation of the vibration shapes in resonances of the circular membrane could be influenced by its asymmetrical characteristics. [ABSTRACT FROM PUBLISHER]

Ti-modified 0.72BiFeO3-0.28PbTiO3 thin films were prepared on Pt/Ti/SiO2/Si substrates by pulsed laser deposition under different oxygen pressures from 2 Pa to 15 Pa. The microstructures and electrical properties were investigated. Tetragonal (001) preferential orientation was observed in all films under different oxygen atmosphere pressures. The electrical properties of the thin films have been investigated for various deposition conditions. The dielectric constant and double remanent polarization were found to be 550 and 80 μC/cm2, respectively, for the thin film deposited at an oxygen atmosphere of 10 Pa and a substrate temperature of 680°C. [ABSTRACT FROM AUTHOR]

In this paper, we have investigated a piezoelectric resonator biosensor based on ferroelectric thin film diaphragm. The diaphragm structure utilizing a flexural vibration mode has been adopted to replace the microcantilever structure in a biosensor. It is an acoustic wave device which can be immobilized with a bio-molecular recognition layer on its surface. Like a microcantilever sensor, the resonance frequency of the diaphragm sensor shifts when the bio-molecular recognition layer reacts with the target species. But a diaphragm sensor has more robust structure comparing with a microcantilever sensor. The responses of the diaphragm biosensor have been simulated using a commercial FEM software package, ANSYS. The prototype devices were fabricated by a conventional method and a MEMS process, respectively. The performance of the sensor was tested and reported. [ABSTRACT FROM AUTHOR]

The piezoelectric membrane, working as flexural acoustic wave devices, is introduced as high performance biosensor platform. Membranes made of polyvinylidene fluoride (PVDF) thin film were fabricated and the influences of size and stress on the resonance behaviors have been investigated. It is experimentally found that membrane could exhibits a nearly same Q factor both in air and in water. Additionally, the microelectronic process combined with megnetron sputtering deposition for fabricating ZnO micro membrane biosensor platform on silicon wafer is established in this paper. [ABSTRACT FROM AUTHOR]

Amorphous Bi1.5Zn1.0Nb1.5O7 (BZN) thin films have been prepared on Pt/TiO2/SiO2/Si(100) substrates by pulsed laser deposition (PLD) process at low temperature. BZN films were deposited at room temperatures under the oxygen pressure from 1 Pa to 30 Pa, and then post-annealed at the temperature below 200°C. XRD analysis indicates that BZN films are still amorphous in nature after the post-annealing. The dielectric constant of amorphous BZN films increases and the dielectric loss decreases after the post-annealing process. The dielectric properties of BZN films are strongly dependent on the oxygen pressure. BZN Thin films deposited at 1 Pa exhibit superior dielectric characteristics. Dielectric constant and loss tangent are 60.2 and 0.006 at 10 kHz, respectively. Leakage current density is less than 1 × 10-7 A/cm2 at 300 kV/cm. [ABSTRACT FROM AUTHOR]

Ferroelectric PbZr0.52Ti0.48O3 (PZT) thin films were prepared by a sol-gel method using SrTiO3 (STO) buffer layers. The effect of SrTiO3 buffer layers on the crystallization and electrical properties of PZT thin films has been investigated. X-ray diffraction shows that the STO buffer layers have a significant effect on the crystallization, orientation and electrical properties of PZT thin films. PZT thin films are fully crystallized at 550°C with SrTiO3 buffer layers. The (111) preferential orientation becomes stronger first with increasing thickness of SrTiO3 buffer layer and then weakens after a critical thickness. The electrical properties, as well as the crystallization mechanism in association with SrTiO3 buffer layers are investigated and discussed. [ABSTRACT FROM AUTHOR]

Lead-free ferroelectric (K0.44Na0.52Li0.04)(Nb0.86Ta0.10Sb0.04)O3 (KNN-LT-LS) thin films have been prepared by a pulsed laser deposition process on Pt/Ti/SiO2/Si substrates. Morphologies, structures and electrical properties of KNN-LT-LS thin films have been investigated as a function of deposition temperature from 680°C to 740°C. X-ray diffraction analysis indicates that KNN-LT-LS thin films are a perovskite phase with a preferential (001) orientation. The dielectric constant and loss tangent of KNN-LT-LS films deposited at 740°C are 1450 and 7.2% at 1 kHz, respectively. The P-E hysteresis loops show that the KNN-LT-LS thin films possess improved ferroelectric properties. The remnant polarization and the coercive field of the films are 7.69 μC/cm2 and 40.8 kV/cm, respectively. [ABSTRACT FROM AUTHOR]

Ba0.5Sr0.5TiO3/Bi1.5Zn1.0Nb1.5O7/Ba0.5Sr0.5TiO3 (BST/BZN/BST) sandwich films have been prepared by a sol-gel method. The sandwich thin films were deposited alternatively by spin coating technique and crystallized by rapid thermal annealing. The structures and morphologies of BST/BZN/BST sandwich thin films were analyzed by XRD and FESEM. The XRD results show that the cubic pyrochlore BZN phase and the perovskite BST phase can be observed in the sandwich thin films annealed at 750°C. The diffraction pattern confirms that no measurable reaction occurred between the BST and BZN phases during the annealing process. The surface of sandwich thin films is compact and crack-free. The BST/BZN/BST sandwich thin films annealed at 750°C exhibit a moderate dielectric constant around 91, a low loss tangent of 0.011, and a relative tunability of 27% at a bias field of 600 kV/cm at 10 kHz. Meanwhile, the FOM (defined as the ratio of tunability and loss tangent at room temperature) of BST/BZN/BST sandwich thin films is 24.5. The relative large dielectric constant, low loss tangent, and high FOM suggest that BST/BZN/BST sandwich thin films have potential application for tunable microwave device applications. [ABSTRACT FROM AUTHOR]

SrNbxTi1-xO3 (0.001 ≤ x ≤ 0.01) thin films have been prepared on Pt/TiO2/SiO2/Si (100) substrates by pulsed laser deposition. X-ray diffracttion and scanning electron microscope studies indicate that all the films were well crystallized and homogeneous with a cubic perovskite structure. Dielectric constant increases from 246 at x equals 0.001 to 342 at x equals 0.01, meanwhile, the dielectric tunability also increases. J-E characteristics of the films suggest that ohmic behavior is predominant at low electric field for all the films, but different conduction mechanisms are predominant at high electric field for the films with different x value. [ABSTRACT FROM AUTHOR]

Lead-free ferroelectric K0.5Na0.5NbO3 (KNN) thick films were successfully prepared by polyvinylpyrrolidone (PVP)-modified chemical solution deposition method. The effect of PVP amount on structures and electrical properties of KNN thick films has been investigated. Thickness of the films is in a range of 0.70 and 4.35 μm depending on the addition amount of PVP in the precursor solutions. All the films show pure perovskite phase. The X-ray photoelectron spectroscopy analysis indicates that PVP has a negligible effect on KNN films when the addition amount is smaller than 0.25. While the increasing amount of PVP can promote the formation of the perovskite phase. The surface morphologies are dense except KNN films with the ratio of PVP monomer to KNN of 1.25. The KNN films with the ratio of PVP monomer to KNN of 1.0 exhibit large dielectric constant of 662 at 1 kHz and the saturated polarization-electric field hysteresis loops. Even though KNN thick films with the ratio of PVP monomer to KNN of 1.25 show the porous morphology, the largest piezoelectric constant d33 of 62 pm/V is obtained. [ABSTRACT FROM AUTHOR]

Lead-free piezoelectric (Na0.52K0.48)NbO3 (KNN) thin films were prepared on Pt/TiO2/SiO2/Si substrates by metallorganic compound decomposition (MOD) method. We discussed the formation mechanism of KNN perovskite phase, it was found that the K4Nb6O17 phase formed first and coexited with KNN phase at lower temperature. With increasing temperature, the diffraction intensity of KNN phase increased gradually, and the pure KNN phase was obtained at 650°C. The KNN thin films possessed higher dielectric constant and lower dielectric loss, and the values of dielectric constant and loss are about 693 and 0.022, respectively. Meanwhile, the ferroelectric, piezoelectric properties and I-V characteristics of KNN thin films were measured and discussed. [ABSTRACT FROM AUTHOR]

Ferroelectric (K0.5Na0.5) NbO3 (KNN) thin films have been successfully prepared by a metallorganic compound decomposition (MOD) method. The stable KNN precursor solutions were prepared from commercial sodium acetate and potassium acetate and niobium ethoxide synthesized in our laboratory. Uniform and dense KNN thin films were obtained using spin-coating and rapid thermal treatment at 500 ∼ 650°C. KNN thin films possess pure perovskite phase and exhibit (110) preferential orientation. The dielectric constant and dielectric loss of KNN thin films annealed at 600°C are about 219 and 0.07 at 1 kHz, respectively. [ABSTRACT FROM AUTHOR]

Ceramics of a novel solid solution system, (1-x)Pb(Zr0.52Ti0.48)O3-xBi(Zn2/3Nb1/3)O3 [(1-x)PZT-xBZN], with compositions near the morphotropic phase boundary (MPB), are synthesized by solid-state reaction method and investigated by X-ray diffraction, dielectric spectroscopy, and ferroelectric and piezoelectric measurements. It is found that the increasing amount of Bi(Zn2/3Nb1/3)O3 (BZN) changes the structure of this system from the tetragonal symmetry to the MPB. The remnant polarization, coercive field and electromechanical properties are significantly enhanced compared with pure PZT ceramics, which is correlated with the MPB feature of the (1-x)PZT-xBZN system. With the increase of BZN content, a gradually diffuse phase transformation with monotonically decreasing Curie temperature and increasing dielectric loss is found. [ABSTRACT FROM AUTHOR]

A novel relaxor solid solution of (1-x)Pb(Mg1/3Nb2/3)O3-xPb(Cd1/3Nb2/3)O3 [(1-x)PMN-xPCN] is synthesized by the solid-state reaction method. The crystal structure, electric properties and relaxor behavior are investigated. This system exhibits an average cubic perovskite structure at room temperature. The cation ordering, which is hardly detectable in the canonical PMN by laboratory-based high-resolution X-ray diffraction, is clearly evidenced in this solid solution. The relaxor behavior of the solid solution is found to be enhanced in the (1-x)PMN-xPCN solid solution compared with PMN. The enhanced relaxor behavior is attributed to be formation of complex ordered and disordered structures, which leads to a broader distribution of the size and dynamics of local polar heterogeneities. [ABSTRACT FROM AUTHOR]