Weijie Dong

Effect Of Europium Doping On Electrical Properties Of Pzt Films

Samples of lead zirconate titanate Pb(Zr0.53Ti0.47)O3 with europium (Eu) doping concentration of 0, 0.5, 1.5, 3 mol% (PEZT) were fabricated by sol–gel method. XRD spectra showed that the introduction of Eu into PZT favored the growth of (100) orientation. With 3% Eu content, the preferential orientation of the film converted from (111) to (100) orientation. The Eu-doped PZT films exhibited lower leakage current less than 10-9 A/cm2 and the behavior of leakage current was discussed in terms of defect chemistry theorem. When Eu content was 1.5%, the remanent polarization (Pr) increased to 28 μ C/cm2 which was much higher than that of undoped PZT film.

Measurement on the actuating and sensing capability of a PZT microcantilever

PZT thin film devices are very competitive when charge signal and force outputs are demanded. A Pb(Zr0.5Ti0.5)O3 thin film with 24 coating layers is deposited by a sol–gel method. An array of three piezoelectric microcantilevers is fabricated using the wet and dry combined bulk micromachining techniques. Each microcantilever has a two-segment top electrode in different dimensions. The actuating and sensing capability of the six segments on the three microcantilevers are measured. It is proved that the proposed piezoelectric microcantilevers have both actuating and sensing functions; different proportion partition results in the diversity of the actuating and sensing capability. At the same location, the longer the piezoelectric segment is, the stronger actuating and sensing capability it has. The maximum actuating sensitivity and sensing sensitivity before poling treatment are 16.7 µN V−1 and 13.44 pC µm−1, respectively, which become about twice as big after poling. We may choose the appropriate microcantilevers to satisfy our purpose on some specific condition where force feedback and object manipulation are needed simultaneously. A hysteresis phenomenon is encountered in the actuating process while not in the sensing process.

Deposition and sensing properties of PT/PZT/PT thin films for microforce sensors

Microforce sensors made of PT/PZT/PT thin films were designed in the micro-Newton range. The PT/PZT/PT thin films were deposited on the Pt/Ti/SiO2/Si substrate by the sol–gel process. Structure and the crystallinity of the deposited films were characterized. The sensing properties of the microforce sensors were measured in static state and in quasi-static state. The sensitivities of the microforce sensors with two different sizes were 0.004 and 0.040 mV μ N−1 in the quasi-static state.

Piezoelectric Microcantilevers with Two PZT Thin-Film Elements for Microsensors and Microactuators

Different from the conventional piezoelectric microcantilevers with a piezoelectric film sandwiched between two metal electrodes on cantilever structures, the objective of our investigation is to develop a technology platform based on the integration of two piezoelectric PZT thin-film elements on silicon cantilevers for microsensors and microactuators. Two novel piezoelectric microcantilevers with two piezoelectric elements (bimorph or two segments of PZT films) and three electric electrodes were designed. The microcantilevers were successfully fabricated by bulk micromachining. The generated piezoelectric charge and actuation force of the microcantilevers were characterized. As microsensors or microactuators, the bimorph piezoelectric cantilevers can increase the sensing resolution and actuation displacement (force) of the piezoelectric cantilevers. The bimorph and two-segment piezoelectric cantilevers can be served as the versatile devices for sensing and actuation. The multifunctional cantilevers have many potential applications in fields such as micromanipulation systems, microrobots, and vibration controls of flexible manipulators.

Preliminary study of calibration system for PZT thin film micro force sensor

Calibration of the micro force sensors is necessary for the measurement of microNewton forces, which are critical to analytical applications of micro force sensor in the analysis of micromanipulators, microrobots and microgrippers. This paper proposes a novel calibration system to calibrate PZT thin film micro force sensor using the bimorph probe as the loading part. Sensitivities of PZT thin film micro force sensors were calibrated by the calibration system composed of the drive system and the testing system. The drive system combines 3-dimensional positioning stage, a bimorph probe and a frequency synthesizer, and the testing system combines an electronic balance for static state or a charge amplifier and a lock-in amplifier for the quasi static state.

Piezoelectric Self-Sensing Actuator for Beam Vibration Control Based on Blind Source Separation

A blind source separation based vibration control method using piezoelectric self-sensing actuator is proposed. Two piezoelectric ceramic patches acting as actuators and two current amplifiers consist of the self-sensing bridge circuit. Each piezoelectric current is a mixture of strain rate current and capacitor current. As they are orthogonal and independent with each other, the blind source separation technique is introduced to obtain the pure strain rate signal. An effort is made to solve the problem of BSS uncertainty in separation order. Open loop experimental results on cantilever beam show the feasibility and validity of the proposed method.

Effect of Thickness on Microstructure and Electrical Properties of PZT Films Prepared by a Modified Sol-Gel Method

A modified sol-gel multiple coating and annealing process was developed to prepare lead zirconate titanate PbZr 0.5 Ti 0.5 O 3 (PZT) thin films with various thickness on Pt(111)/Ti/SiO 2 /Si(100) substrates. The PZT films with thickness 280, 560 and 810 nm underwent one, two and three annealing cycles, respectively, which consisted of 5 coating layers, 10 coating layers and 15 coating layers. Surface morphology and phase structure of the thin films were studied by SEM and XRD, respectively. The relationship between the thickness, namely different annealing cycles, and degree of texture was investigated. The dielectric constant increases with increasing film thickness. The dielectric constant and dielectric loss of PZT films as functions of applied field and frequency had also been examined and discussed.

Study on Contact Microforce Measurement Based on Piezoelectric PZT Thin Film

PZT thin film sensors are widely used in microsensor because of its simple structure, high sensitivity and good linearity. The sol-gel method is used for the PZT thin film deposition on the silicon cantilever structure, actuation and sensing electrodes are made on the PZT micro-cantilever by the bulk micromachining technology. AC voltage is applied to the actuation electrode to make the micro-cantilever oscillate at 70 Hz, and the charge on the sensing electrode serves as sensor signal. When contact force is applied to the tip of the micro-cantilever, the amplitude variation of the induced charge is collected by a charge amplifier and a digital lock-in amplifier. Experiments have shown that the PZT thin film sensors with the micro-cantilever structure are able to sense contact force whether the PZT thin film is in the state of stretching stress or compressive stress. The resolution of the microforce sensor is 3 muN at the stretching stress, and 3.75 muN at the compressive stress

Preparation and Properties of Pb1-xSrx (Zr0.53Ti0.47) O3 Thin Films by Sol-Gel Method

Pb1-xSrx (Zr0.53Ti0.47) O3 (PSZT) thin films with different x values (x = 0, 0.02, 0.04, 0.06) are prepared by sol-gel method and their properties are studied. All PSZT thin films get a single perovskite phase. The dielectric properties are studied. The leakage current density at an applied electric field of 61.2 kV/cm is 293.0 × 10−9A/cm2 when x = 0.04. The remanent polarization and coercive field values of the PSZT (x = 0) thin film are 8.4 μC/cm2 and 67.5kV/cm, respectively.