Junjie Gao

The hydrostatic pressure dependence of the piezoelectric properties for the barium titanate and lead titanate crystals: Thermodynamic analysis

The influence of the hydrostatic pressure on the piezoelectric response for tetragonal BaTiO3 and PbTiO3 monodomain crystals is investigated using Landau–Ginzburg–Devonshire phenomenological approach. It is shown that hydrostatic pressure could enhance the piezoelectric properties in some directions of crystals. The piezoelectricy enhancement is attributed to the hydrostatic pressure-induced flattening of the elastic Gibbs free-energy profile and its corresponding dielectric softening. For BaTiO3 at 285 K, with increasing pressure, the free-energy profile tends to become flat along the polar [001]c direction, facilitating the dilatation and contraction of polarization. So the dielectric softens and the d33 obviously increases in the [001]c direction. But in the direction perpendicular to the polarization, the free-energy profile goes to steepen, which restrains the polarization rotation away from the [001]c polar axis and in turn makes the shear piezoelectric coefficient d15 decreased. As a result, the ma...

An efficient way to enhance output strain for shear mode Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 crystals: Applying uniaxial stress perpendicular to polar direction

The shear piezoelectric behavior of [001] poled tetragonal and [011] poled rhombohedral Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) crystals, with “1T” and “2R” domain configurations, respectively, were investigated under uniaxial stress perpendicular to polar direction. The shear piezoelectric coefficient d15 was found to decrease with increasing compressive stress for both “1T” and “2R” crystals. Based on thermodynamic analysis, the phase structure can be stabilized by applying compressive stress perpendicular to polar direction, resulting in a “harder” polarization rotation process, accounts for the reduced shear piezoelectric coefficient. Of particular importance is that the allowable drive electric field was greatly increased and transverse dielectric loss was drastically reduced under compressive stress, leading to the improved maximum-shear-strain.

Pyroelectric properties of rhombohedral and tetragonal Pb(In1/2Nb1/2)-Pb(Mg1/3Nb2/3)-PbTiO3 crystals

Pyroelectric properties of rhombohedral and tetragonal single crystals Pb(In1/2Nb1/2)-Pb(Mg1/3Nb2/3)-PbTiO3 (PIN-PMN-PT) were investigated, with temperature from −100 °C to 100 °C. At room temperature, the pyroelectric coefficient p and the figure of merit Fd of rhombohedral crystals are 7.81 × 10−4 C/m2 K and 10.9 × 10−5 Pa−1/2, respectively, and 6.84 × 10−4 C/m2 K and 11.67 × 10−5 Pa−1/2, respectively, for tetragonal crystals. Although the coefficient p and Fd at room temperature are similar for rhombohedral and tetragonal crystals, the Fd of tetragonal crystal is much more stable with respect to temperature, owing to its higher phase transition temperature and stable mono-domain state. From room temperature to 100 °C, the Fd of rhombohedral crystal decreases from 10.74 × 10−5 Pa−1/2 to 5.3 × 10−5 Pa−1/2, while that of tetragonal crystals is nearly independent of temperature. Such investigation reveals that tetragonal PIN-PMN-PT crystal is more suitable for uncooled infrared detectors and imagers when c...

The effect of the hydrostatic pressure on the electromechanical properties of ferroelectric rhombohedral single crystals Pb(Mg1/3Nb2/3)-Pb(In1/2Nb1/2)-PbTiO3

The electromechanical properties of rhombohedral single crystals Pb(Mg1/3Nb2/3)-Pb(In1/2Nb1/2)-PbTiO3 (PMN-PIN-PT) were investigated under hydrostatic pressure from 0.1 to 456 MPa. Due to pressure-induced morphotropic phase boundary moving, the piezoelectric coefficients and electromechanical coupling factors of PMN-PIN-PT crystals were found to decrease by ∼10% and ∼2%, respectively. The mechanical quality factor Q was found to dramatically decrease, because the domain wall motion and friction between vibrator and pressure-transmitting fluid were enhanced under hydrostatic pressure. On the other hand, the pressure induced depolarization and phase transition were not observed in the experimental pressure range.

Evolution of transverse piezoelectric response of lead zirconate titanate ceramics under hydrostatic pressure

The piezoelectric properties of 31-mode resonators of lead zirconate titanate ceramics under hydrostatic pressure from 0.1 to 325 MPa were evaluated by a fitting method, in which mechanical loss was taken into account. Our results based on the fitting method showed a hydrostatic pressure independent tendency of the piezoelectric coefficient and the electromechanical coupling factor because the adopted PZT ceramic can be considered as a linear system in our experiment, while two misleading tendencies of piezoelectric coefficient were obtained based on the resonance method when ignoring the contribution of the mechanical loss.

Study on the Dielectric Properties of 0.75Pb(Mg1/3Nb2/3)O3–0.25PbTiO3 Ceramic Under Hydrostatic Pressure

The dielectric properties of 0.75Pb(Mg1/3Nb2/3)O3-0.25PbTiO3 (PMN-25PT) ceramic under hydrostatic pressure and pressure-induced phase transition were investigated. PMN-25PT ceramic is pure perovskite with weak relaxation at 1 bar. With increasing hydrostatic pressure, the temperature, T m, of top dielectric constant decreases, °C/kbar, frequency dispersion and phase transition diffuse increases, remnant polarization decreases continuously. The hydrostatic pressure dependence of dielectric constant () is similar to the temperature dependence of dielectric constant. The relax ferroelectric-paraelectric (RFE-PE) phase transition was induced by hydrostatic pressure and the transition was gradual change process with stronger relaxor behavior than by temperature-induced.

Ferroelectric phase transitions and electromechanical properties of barium titanate and lead titanate crystals under uniaxial and shear stresses: a thermodynamic analysis

Ferroelectric phase transitions and electromechanical properties of BaTiO3 (BT) and PbTiO3 (PT) crystals under uniaxial and shear stresses are investigated using the Landau–Devonshire phenomenological approach. The results show that (1) the Curie temperature of BT and PT crystals increases with increasing stress; (2) at room temperature, no ferroelectric–ferroelectric phase transition is induced by uniaxial stress along the [1 0 0]c direction for the PT crystal, while the orthorhombic phase is the ultimate stable state for BT and PT crystals under uniaxial stress along the [0 0 1]c direction and shear stress; (3) shear stress induces a temperature-independent morphotropic phase boundary in tetragonal phase BT and PT crystals; (4) the dielectric and piezoelectric properties are closely related to the phase transition induced by external stresses, where nonlinearity is observed owing to higher order terms of free energy.

THE HYDROSTATIC PIEZOELECTRICITY OF RELAXOR-PbTiO3 FERROELECTRIC CERAMICS AND CRYSTALS

The hydrostatic piezoelectricity of Pb(Mg1/3Nb2/3)–xPbTiO3 (PMN–xPT) ceramics and PMN–0.32PT and Pb(Mg1/3Nb2/3)–Pb(In1/2Nb1/2)–PbTiO3 (PMN–PIN–PT) crystals were investigated through a quasi-static method. The results showed that pressure-induced depolarization occurred in PMN–xPT ceramics when pressure was above about 50 MPa, while there was no obvious pressure-induced depolarization for PMN–0.32PT and PMN–PIN–PT crystals in the whole pressure range (0~530 MPa). The hydrostatic piezoelectric coefficient dh of PMN–0.32PT and PMN–PIN–PT crystals was nearly independent of pressure. The dh of mono-domain orthorhombic and tetragonal phase crystals is slightly larger, on the order of 100 pC/N. In addition, the relationship between the hydrostatic piezoelectric coefficient dh and the longitudinal and transverse piezoelectric coefficients d33 and d31 for different crystal systems was summarized.

Influence of hydrostatic pressure on electric field induced phase transition of PbLa(Zr,Sn,Ti)O3 ceramic

Abstract The electric field induced antiferroelectric–ferroelectric (AFE–FE) phase transition of Pb0·97La0·02(Zr0·75Sn0·136Ti0·114)O3 ceramic under hydrostatic pressure was investigated by dielectric spectroscopy. The results show that the phase transition electric field EAFE–FE increases with increasing pressure, and the dielectric constant with dc bias electric field has no distinct variation when the hydrostatic pressure was >200 MPa. From the results above, the partial EAFE–FE–pressure phase diagram of the Pb0·97La0·02(Zr0·75Sn0·136Ti0·114)O3 ceramic was obtained.

Dielectric properties of [001]-oriented Pb(Mg1/3Nb2/3)O3–PbTiO3 single crystal under hydrostatic pressure

The dielectric properties of [001]-oriented 0.76Pb(Mg1/3Nb2/3)O3–0.24PbTiO3 (PMN–PT24) crystal were investigated as a function of frequency and temperature under hydrostatic pressure. The dependence of remnant polarization of the PMN–PT24 crystal on pressure was also measured. The results showed that both the temperature of the maximum dielectric permittivity T m and the depoling temperature T d of the PMN–PT24 crystal shifted to lower temperature, and the relaxor property became stronger with increasing hydrostatic pressure. The remnant polarization (P r) of the PMN–PT24 crystal decreased linearly with increasing pressure. Consequently, the hydrostatic piezoelectric coefficient, d h, was calculated.