Taosheng Zhou

Lead-free In2O3-doped (Bi0.5Na0.5)0.93Ba0.07TiO3 ceramics synthesized by direct reaction sintering

Lead-free (Bi0.5Na0.5)0.93Ba0.07TiO3–xwt%In2O3 ceramics synthesized by direct reaction sintering have been studied. X-ray diffraction reveals that all (Bi0.5Na0.5)0.93Ba0.07TiO3–xwt%In2O3 ceramics are of a perovskite structure with coexistence of rhombohedral and tetragonal phases. It is found that the direct reaction sintering promotes growing of ceramic grains while doping of In2O3 contributes to inhibit and homogenize the grain growth, as shown by scanning electron microscopy. The ceramics show excellent piezoelectric and dielectric properties with thickness electromechanical coupling factor kt=0.503, piezoelectric constant d33=205pC∕N, dielectric constant e33T∕e0=1046, and loss tangent tanδ=0.036.

The Effects of Ta Substitution and K/Na Ratio Variation on the Microstructure and Properties of (K,Na)NbO3-Based Lead Free Piezoelectric Ceramics

Abstract[(Na0.5+yK0.5−y)0.94Li0.06][(Nb0.94Sb0.06)1−xTax]O3 + 0.08 mol% MnO2 lead-free piezoelectric ceramics were fabricated successfully by a conventional solid-state reaction method. The effects of Ta5+ substitution and K/Na ratio variation on the microstructure and properties of the ceramics have been systematically investigated. With the increasing of Ta5+ substitution content, the orthorhombic–tetragonal transition temperature To–t presents obvious “V” type variation while the Curie temperature Tc decreases monotonically. The ceramics properties were further enhanced by adjusting the Na/K ratio of the A-site. Under systematical optimization of the A-site and B-site elements, good overall electrical properties of d33 = 276 pC/N, kp = 44.5%, ε33T/ε0 = 1,175, tanδ = 0.027, Tc = 309 °C, Pr = 21.0 μC/cm2, and Ec = 1.14 kV/mm were obtained for ceramics with Ta5+ content x of 0.05 and Na/K ratio of 57/43 (y = 0.07).

Preparation of a modified (Pb,Ca)TiO3 piezoelectric ceramics with binary complex elements substitution in B-site

Abstract Preparation of a modified (Pb,Ca)TiO3 with (Zn1/2W1.2) (Ni1/2Nb1/2) substitution in B-site had been studied. Adding suitable amounts of MnCO3 in this modified PbTiO3 piezoelectric ceramics, the material performances could be improved further. Optimized fabricating procession had also been investigated. Study showed that the modified (Pb,Ca)TiO3 piezoelectric ceramics had large anisotropy high mechanical quality factor and curie temperature lower dielectric constant and loss. The microstructure of the ceramics and a kind of micro-domain had been observed by XRD and TEM.

Thermal decomposition of ktn gel and formation of perovskite structure KTN

Abstract This paper reported the thermal decomposition process of KTN Gel and the formation process perovskite structure KTN. Two pyrochlore phases formed in the heat treatment process, one was potassium-deficient pyrochlore phase K3Ta5O14 • 5H2O, another was potassium-rich pyrochlore phase K3Nb2O6(O, OH) • nH2O. The transformation of two pyrochlore phases and perovskite structure KTN were influenced by the potassium content and the heat treatment temperature. The pyrochlore phases readily formed at a lower temperature, at a higher temperature (680°C-750°C), the pyrochlore phases transformed to the pure perovskite structure KTN, but the perovskite structure KTN would decompose to form potassium-deficient pyrochlore phases Ta2O5 • n(KTaO3)(n=2, 3, 4) with the temperature gone np(>950°C). When potassium was excess in the starting materials, the transformation temperature of the pyrochlore phases to perovskite phase was higher, even at 1200°C. When K/Ta, Nb < 1 in the starting materials, the pure perovskite ...

Improved thermally stimulated current techniques and quenching polarization of polypropylene

Abstract Step heating TSC as well as bound charge and residual charge measurements were performed in polypropylene (PP) to give static TCS spectra. All the results demonstrated good agreement of a –15°C temperature shift relative to the spectrum of normal TSC at a rate of 2°C/min. By carefully examining the discharge sources, a charging method was proposed to study the variation of stored polarized charges on the quenching process. The quenching polarization current showed a charging peak. The reason for this was that the structure or configuration of the polymer at a high temperature is kept at a lower temperature and this structure can hold more bound charges in the lower temperature than in the higher temperature. Thermal-cycle polarized TSC measurements further show that some bound charges enter into deeper energy levels in the quenching polarization process. This result provides a better means of polymer preparation and shows the danger of using the polymer in a high DC field or radiation conditions.

Study of low—temperature sintering modified PbTiO3 piezoelectric ceramic

Abstract A new low-temperature sintering modified PbTiO3 piezoelectric ceramic material was prepared by adding Bi(Cd1/2Ti1/2)O3, MnO2, SiO2. The modified PT material has excellent properties such as low-sintering temperature, high piezoelectric activities, large piezoelectric anisotropy, high mechanical quality factor, low dielectric constant and dielectric loss. The main parameters are Kt=0.49, Kp=0.027, Kt/Kp=18.2, d33=65 × 10−12C-N−1, Qm=514, ρv = 7.4 × 103kg−m−3, Tc=312°C, ε T 33/ε0 = 177, tanδ=0.63%. It shows great application prospects in the fields of multilayer piezoelectric filter and multilayer piezoelectric step-down transformer.

Piezoelectric ceramic coupler and the applyed on relays

Abstract A long-shaped piezoelectric ceramic coupler based on piezoelectric effect and inverse piezoelectric effect is fabricated with the material of modified PZT (PbZrO3-PbTiO3). And the main technical parameters of the coupler are: ε>1500, Kp>60,d33>450, Qm >600. The coupler has advantages in good signal transmission and strong anti-interference. In contrast to traditional relays, the new type of relay with the coupler possesses excellent anti-interference feature, high trigger sensitivity, as well as shorter switching-on time. This new relay will have a very good applied prospect.

The study of piezoelectric ceramic-metal composite with single cavity

Abstract A piezoelectric ceramic-metal composite with single cavity has been developed. The composite has not only high piezoelectric strain constant, also advantages of small position-dependence, easy manufacture and high stability, which make it fixed easily. The optimum dimensions of composite have been obtained by experiment. The relative effective piezoelectric strain constant is 7890pC/N which is 24 times that of PZT piezoelectric ceramic (d 33=330pC/N).

A standing wave type ultrasonic motor

Abstract A standing wave type ultrasonic motor using a piezoelectric ceramic rectangular bar as stator has been successfully developed. Its main performance parameters and applications such as ultrasonic step motor, clock model, and paper feeder etc are reported in this paper.

Studies on a new type of PbTiO3 piezoelectric ceramic materials

Abstract A new type of modified PbTiO3 piezoelectric ceramic materials added with Pb(Mn1/3Sb2/3)O3, CaCO3, Bi2O3, NiO has been investigated. The typical composition of these materials is Pb0.80Ca0.20[(Mn1/3Sb2/3)0.05Ti0.95]O3 added with 0.5wt%NiO and lwt%Bi2O3. Under optimized fabrication processing, its main performance parameters are described as follows: Kt=0.61, Kp≌0, d33=70×10-12C * N-1; ϵ33 T/ϵ0=161, tg δ =0.01; Qm=43, Nt=2004Hz * m.