Xuezheng Ruan

Observation of an unusual optical switching effect in relaxor ferroelectrics Pb(Mg1/3Nb2/3)O3-Pb(Zr0.53,Ti0.47)O3 transparent ceramics

We present an unusual optical switching effect in relaxor ferroelectrics Pb(Mg1/3Nb2/3)O3-Pb(Zr0.53,Ti0.47)O3 transparent ceramics under strong AC electric fields, which is accompanied by a peculiar dielectric response rarely reported previously and attributed to the disruption of the ferroelectric domain structure by the strong AC field. The results provide further understanding on the domain behaviors under electric fields of the relaxor ferroelectrics and the potential for advancing electro-optic applications.

Contribution to the large and stable electric field induced strain for textured Pb(Mg1/3Nb2/3)0.675Ti0.325O3 ceramics

Textured Pb(Mg1/3Nb2/3)0.675Ti0.325O3 (PMN-PT) ceramics were prepared by the templated grain growth method with 3% plate-like BaTiO3 as templates. The degree of grain orientation was about 81% by calculating from the XRD pattern. Temperature dependence of electric field induced strain was measured for both untextured and textured PMN-PT ceramics. The results show that the electric field induced strain for textured PMN-PT ceramics is much larger and more stable than that for untextured PMN-PT ceramics in a wide temperature range. The contribution from the piezoelectric effect and electrostrictive effect to the strain was analyzed, and it was found that textured PMN-PT ceramics exhibited electrostrictive coefficient Q33 as high as 5.19 × 10−2 m4 C−2 and it was comparable to that of PMN-PT single crystals. The electrostrictive effect contributed the main part of the enhancement of electric field induced strain for textured PMN-PT ceramics.

Elastic and Electric Damping Effects on Piezoelectric Cantilever Energy Harvesting

Piezoelectric cantilever is one of the simplest configurations for energy harvesting. Many reports have shown that the resonances frequency of the piezoelectric energy harvesting (PEH) can be essentially shifted by the proof masses to the lower working frequencies in practice, and its high electric capacity is required to decrease its output electric impedance to match the electric load resistant. However, there are few reports to investigate the mechanical vibration damping ratio of PEH affected by the proof masses and output electric loads. In this study, the mechanical damping ratio (ζm) of PEHBC with zero proof mass, and the electric damping ratio (ζe) related to the electric load, the mechanical vibration damping ratio with proof mass and the electric load are measured and discussed for the piezoelectric bimorph cantilever energy harvesting (PEHBC). The damping ratio was calculated by the time dependence of tip displacement or velocity amplitude of PEHBC using a laser vibrometer. A theoretical analysis was carried out to correlate the damping behaviors of the cantilever to the proof mass and the electric resistive load. A good agreement is observed by the two sets of data.

Enhancement of Piezoelectric Properties of PMN-PT Ceramics at Low Temperatures

The temperature dependence of dielectric, elastic, electromechanical, and piezoelectric properties of (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT) ceramics near MPB with x = 0.33, 0.35, 0.36, 0.37, and 0.38 was systematically investigated within the temperature range 120–360 K. Compositions of x = 0.37 and 0.38 were found to exhibit temperature-independent piezoelectric properties over a temperature range from 185 to 360 K. The temperature-stable piezoelectric response was attributed to a counter-balance among the dielectric, elastic, and electromechanical responses in a broad ferroelectric phase transition that was revealed from the dielectric constant, elastic compliance constant, and electromechanical coupling factor.

Phase Transitional Behavior and Dielectric Properties of (Ba,Ca)(Ti,Zr)O3–Bi(Zn,Zr)O3 Lead-Free Ceramics

The (1-x)(Ba0.98Ca0.02)(Ti0.95Zr0.05)O3–xBi(Zn0.5Zr0.5)O3 [BCZT–xBZZ, x = 0.005–0.06] lead-free solid solution ceramics were synthesized by a conventional solid state reaction method. The effect of Bi(Zn0.5Zr0.5)O3 addition on the crystal structure, microstructure, relaxor behavior and dielectric properties of the (Ba0.98Ca0.02)(Ti0.95Zr0.05)O3 ceramics has been studied. X-ray diffraction shows that all the ceramics possess a single phase of perovskite structure. The BCZT–xBZZ ceramics change from tetragonal phase to pseudocubic phase with the content of BZZ increasing. Moreover, the grain size is affected by BZZ addition. The BCZT–xBZZ ceramics become considerably dense with the proper amount of BZZ introduction. The relative permittivity ϵr and loss tangent tanδ vary with the increasing BZZ content. Temperature dependence of the dielectric properties indicates that as the concentration of BZZ increases, the BCZT–BZZ solid solution ceramics exhibit more relaxor-like behavior. Furthermore, the BCZT–xBZZ ceramics exhibit low dielectric loss and excellent dielectric temperature stability in a wide temperature range, which indicates a potential application in devices under comparably high-temperature environment.