Papers by Keyword: Piezoelectric Ceramic (PZT)

Abstract: Nonlinear magneto-electric response characteristics of giant magnetostrictive-piezoelectric composite sensors in harmonic and stochastic magnetic fields were studied in this paper. Van der Pol nonlinear difference items were introduced to interpret the hysteresis phenomena of both giant magnetostrictive material and piezoelectric ceramics. The nonlinear dynamic model of giant magnetostrictive-piezoelectric composite sensors in harmonic and stochastic magnetic fields was developed. The expression of dynamic response of the system was obtained, and the bifurcation characteristics of the system were analyzed. The magneto-electric coefficient of the composite sensors was determined, and the effects of system parameters on the dynamic characteristics and magneto-electric coefficient of the system were analyzed. The simulation results show that there are stochastic Hopf bifurcation and jump phenomena of vibration amplitude in the system, and both of that can be avoided through adjusting parameters. The experimental results show that the system’s motion becomes chaotic when stochastic excitation is extremely large. The results of this paper are helpful for optimal design and improvement of giant magnetostrictive-piezoelectric composite sensors.

Abstract: Doping effect on the lattice parameters, vibration modes, dielectric and piezoelectric properties of LiSbO₃, LiTaO₃ and LiNbO₃ substituted lead-free K_0.5Na_0.5NbO₃ (KNN) ceramics are investigated. All compositions are crystallized in morphotropic phase boundary region. Enhanced piezoelectric and electromechanical response d₃₃ ~176–197 pC/N, k_p ~45%–48%, and k_t ~34%–47% obtained in the doped ceramics are due to the presence of the polymorphic phase transition between orthorhombic and tetragonal phase at room temperature.

Abstract: Submicron-structured (Bi_0.5Na_0.5)_0.94Ba_0.06TiO₃ (BNBT6) dense ceramics, from nanometric powder synthesized by sol gel auto-combustion at 500°C and obtained by hot-pressing (800°C-2h) and subsequent recrystallization at moderate temperature (1000-1050°C-1h), have been studied. In-situ measurements at the shear mode of electromechanical resonance of non-standard thickness-poled shear plates as a function of the temperature show higher depolarization temperature than measurements at the radial mode of thin disks. Shear mode related material coefficients are measurable up to 160°C, being k₁₅≈30% and d₁₅≈250 pC.N^-1 at 130°C. Depolarization is a complex phenomena caused by a ferroelectric (FE) macrodomains thermal randomization and a phase transition from the field-induced FE phase to a relaxor phase. The early stage of such a transition involves a non-negligible piezoelectricity arising most probably by the percolative coexistence of ferroelectric macrodomains in the resonator under the given stress field for each resonance mode.

Abstract: Samples exhibiting substitution of Titanium in Bismuth-Sodium-Titanate (BNT) by isovalent Zirconium, Tin and Germanium (Bi_0.5Na_0.5Ti_(1-x)D_xO₃ with D = Zr, Ge and Sn and x = 0.0025; 0.0050; 0.01; 0.02; 0.04; 0.08) were investigated with respect to microstructure, relative permittivity, loss factor and polarization. The substituents differ in mass, ionic radius and d-electron configuration. The shift of transitions observed in plots of permittivity and loss factor vs. temperature indicate the influence of the ionic radius. The occurrence of a pinched hysteresis loop at ambient temperature in the Sn-doped samples and the absence of any pinching in the hysteresis loops of Zr-and Ge-doped samples give rise to the assumption that this feature of polarization is connected to the ionic radius combined with the d¹⁰ electron configuration of Sn⁴⁺.

Abstract: In order to resolve the operation difficulty, high cost problems of traditional manual cell microinjection, a low-cost microinjection system based on hybrid-driven micro-robot is presented. System is mainly composed of microscope, 3-DOF(degrees of freedom) micro-robot, signal generator and power amplifier. Firstly, we describe the automated microinjection system. Secondly, we analyze the motion performance of the robot in the horizontal and vertical direction. The single step resolution is less than 5um each step working at a frequency more than 200Hz. Maximum range of vertical motion is 5mm and minimum resolution ups to 2um. Finally, shrimp egg microinjection experiment is conducted using our system. The experimental result shows that this proposed scheme is simple, reproducible and can achieve microinjection success rate of 88%.

Abstract: According to the characteristics of ultrasonic guided wave inspection, An exciting power, used for exciting ultrasonic guided waves in pipeline is designed based on DDS and FPGA. The excitation source consists of FPGA, D/A conversion circuit, a low-pass filter circuit and power amplifier circuit. Constructing DDS based on FPGA as the controller and signal generator. Filter circuit and power amplifier circuit are designed in this paper. The experiment results show that the excitation source can have high voltage and high frequency output capability, and can generate desired signal type with a good accuracy to fit the requirements in practice. It can be conveniently used for pipeline ultrasonic guided wave detection.

Abstract: Instantaneous signal and alternating signals are as driven signals, using PID control, change control coefficient P's size, The stopping time of impact force under instantaneous signal with the piezoelectric ceramic content increases, the stopping time is reduced; after applying active control, the stopping is shorter than that is not applied. After applying the alternating signal to force the cantilever beam, the driving effect of the ceramic sheet is located in a cantilever position A, B, C, the effect of C under controlling is at best. The effect of two driven ceramic sheets is better than that of three driven ceramic sheets, the best control position is B+C.

Abstract: It is designed a Fast Tool Servo (FTS) device which based on piezoelectric ceramic and jointed by flexible hinge. The flexible hinge has been analyzed and optimized both by the theoretical calculation and finite element analysis; and it has been physically manufactured and tested by means of pressure sensor and laser interferometer. The stiffness model was established. The driving voltage and displacement relationship has been revealed. The results indicate that this FTS system can reach a travel range for 60μm,the frequency response precedes 150Hz within 39μm travel range.

Abstract: In this paper, a portable underwater acoustic transducer sensitivity test device is designed to overcome the disadvantages of traditional test methods, such as the bigger size of anechoic pool, and single function of the vibrating column of liquid method. This new design has the advantage of small size, easy to carry and implement. A model of this device is constructed based on the finite element analyse software COMSOL Multiphysics. By calculating the sound field distribution of the test device model, the optimization size of the piezoelectric ceramic can be determined. Also the effect of some other key parameters, such as the material of vessel and thickness, are considered. All these results can provide the theoretical basement of the design of portable underwater acoustic transducer in practice.

Abstract: Different processing conditions and the effect of secondary phases on ferroelectric properties of Bi_0.5(Na_0.8K_0.2)_0.5TiO₃ (BNKT) are studied. Ceramic powders are prepared by solid state reaction and different sintering temperatures (temperatures between 1075 and 1150°C) are analyzed. Finally, samples are characterized by X-ray diffraction, Raman microspectroscopy, Scanning Electron Microscopy, impedance spectroscopy, and density measurements. Through XRD patterns, the perovskite structure is stabilized; together with small peaks corresponding to a secondary phase associated with K_2-xNa_xTi₆O₁₃ phase. Moreover, the content of the secondary phase, d₃₃ piezoelectric constant and dielectric properties increase with sintering temperature.