Dabin Lin

Domain size engineering in tetragonal Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 crystals

The effect of domain size on the dielectric and piezoelectric properties of [111]-oriented tetragonal Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 crystals was investigated. The dielectric permittivity (ɛ33 T/ɛ0) and piezoelectric coefficient (d33) were found to be on the order of 13 800 and 1630 pC/N, respectively, for samples with domain size of ∼500 nm, a 3-fold increase to crystals with domain size of ∼50 μm. Rayleigh analysis revealed that the extrinsic contribution to the piezoelectric response increased from ∼8% to 30% with decreasing domain size, due to the increased domain wall density and associated irreversible domain wall motion. The enhanced properties were thought to relate to the fine domain structures, however, showing a poor electric field and temperature stabilities with domain size of 500 nm. Of particular significance is that samples with domain size being on the order of 5 μm exhibit field and temperature stabilities, with yet high piezoelectric properties, make it potential for transduce...

Piezoelectric activity in Perovskite ferroelectric crystals

Perovskite ferroelectrics (PFs) have been the dominant piezoelectric materials for various electromechanical applications, such as ultrasonic transducers, sensors, and actuators, to name a few. In this review article, the development of PF crystals is introduced, focusing on the crystal growth and piezoelectric activity. The critical factors responsible for the high piezoelectric activity of PFs (i.e., phase transition, monoclinic phase, domain size, relaxor component, dopants, and piezoelectric anisotropy) are surveyed and discussed. A general picture of the present understanding on the high piezoelectricity of PFs is described. At the end of this review, potential approaches to further improve the piezoelectricity of PFs are proposed.

Electric-field and temperature induced phase transitions in Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 single crystals

Electric-field and/or temperature induced phase transitions were observed using polarizing light microscope on [100]-oriented Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 (PMN–0.3PT) single crystals with electric fields applied along the [001] and [011] directions, respectively. The monoclinic (M) and tetragonal (T) phases were observed with electric field applied along the [001] direction at 5 and 9 kV/cm, respectively. The orthorhombic (O) and T were observed with 5 kV/cm and 10 kV/cm electric field applied along the [011] direction, respectively. The intermediate phases [M and/or O phase(s)] were also confirmed by the temperature-dependent dielectric behavior.

Ultrahigh piezoelectricity in ferroelectric ceramics by design

Piezoelectric materials, which respond mechanically to applied electric field and vice versa, are essential for electromechanical transducers. Previous theoretical analyses have shown that high piezoelectricity in perovskite oxides is associated with a flat thermodynamic energy landscape connecting two or more ferroelectric phases. Here, guided by phenomenological theories and phase-field simulations, we propose an alternative design strategy to commonly used morphotropic phase boundaries to further flatten the energy landscape, by judiciously introducing local structural heterogeneity to manipulate interfacial energies (that is, extra interaction energies, such as electrostatic and elastic energies associated with the interfaces). To validate this, we synthesize rare-earth-doped Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT), as rare-earth dopants tend to change the local structure of Pb-based perovskite ferroelectrics. We achieve ultrahigh piezoelectric coefficients d33 of up to 1,500 pC N−1 and dielectric permittivity ε33/ε0 above 13,000 in a Sm-doped PMN–PT ceramic with a Curie temperature of 89 °C. Our research provides a new paradigm for designing material properties through engineering local structural heterogeneity, expected to benefit a wide range of functional materials.Simulations were used to investigate the effects of local structural heterogeneity on piezoelectricity in ceramics. From this, a Sm-doped PMN–PT composition was designed with an extremely high piezoelectric coefficient for polycrystalline systems.

Domain size engineering in 0.5%MnO2-(K0.5Na0.5)NbO3 lead free piezoelectric crystals

The piezoelectric property of [001]-oriented 0.5%MnO2-(K0.5Na0.5)NbO3 (Mn-KNN) crystals was studied as a function of domain size, being poled with different electric fields at 205 °C (above orthorhombic to tetragonal phase transition temperature To-t). The piezoelectric coefficients d33 and relative dielectric constants er were found to increase from 270 pC/N to 350 pC/N and 730 to 850 with the domain size decreasing from 9 to 2 μm, respectively. The thermal stability of piezoelectric property was investigated, where the d33 value for [001]-oriented Mn-KNN crystals with domain size of 2 μm was found to decrease to 330 pC/N at depoling temperature of 150 °C, with minimal variation of ∼6%. The results reveal that domain size engineering is an effective way to improve the piezoelectric properties of Mn-KNN crystals.

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.

Temperature Dependence of Domain Structure in (K0.17Na0.83)NbO3 Lead Free Piezoelectric Single Crystal Grown by Bridgman Method

Lead free piezoelectric single crystals of (K0.17Na0.83)NbO3 have been successfully grown by the solution Bridgman method. The chemical composition of the obtained single crystal was determined by electron probe microanalysis (EPMA), showing that the K/Na ration is derivate from the theoretical ratio. The crystal was examined also by X-ray diffraction and dielectric measurements. The optical study of (K0.17Na0.83)NbO3 single crystal shown three phase transition at 223°C, 412°C and 472°C in heating and at 198°C, 408°C and 478°C during cooling, while dielectric measurements performed on (K0.17Na0.83)NbO3 single crystal exhibited phase transitions at 206°C and 424°C, respectively.

In-situ observation of domain wall motion in Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 crystals

Various domain structures, including wave-like domains, mixed needle-like and laminar domains, typical embedded 90° and 180° domains, have been observed in unpoled rhombohedral, monoclinic, and tetragonal Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) crystals by polarizing light microscope; while in poled tetragonal crystals, the parallel 180° domains were reversed and only vertical 90° domain walls were observed. For 0.24PIN-0.42PMN-0.34PT crystals with morphotropic phase boundary composition, the domain wall motion was in-situ observed as a function of applied electric field along crystallographic [100] direction. With increasing the electric field from 0 to 12 kV/cm, the rhombohedral (R) domains were found to change to monoclinic (M) domains and then to tetragonal (T) domains. The electric field-induced phase transition was also confirmed by X-ray diffraction and the temperature-dependent dielectric behavior.

The polarization fatigue behavior in Pb(Mg1/3Nb2/3)O3-0.32PbTiO3 single crystals

Polarization hysteresis (P-E) change was investigated as a function of the strength, frequency and cycles of electric field alternating for [001]c, [110]c, [111]c oriented Pb(Mg1/3Nb1/3)O3-0.32PbTiO3 (PMN-0.32PT) single crystals. Under 1.5kV/cm ( Ec), obvious polarization fatigue was presented for [001]c, [110]c, [111]c orientations and the biggest fatigue rate was around ~70% in [110]c orientations after 105 cycles. The fatigue rate decreased with the increasing of electric field frequency. The influences of crystallographic orientation and electric field strength and frequency on polarization fatigue behavior in PMN-0.32PT single crystals was discussed based on space charge, domain reverse and phase transition process.

Evaluation of PMN-PT based crystals for various applications

Pb(Mg<inf>1/3</inf>Nb<inf>2/3</inf>)O<inf>3</inf>-PbTiO<inf>3</inf> based ferroelectric single crystals have been extensively studied for various applications. In this paper, the advantages and issues of crystals are discussed, based on requirements of transducers, actuators and sensors, with emphasis on Pb(In<inf>0.5</inf>Nb<inf>0.5</inf>)O<inf>3</inf>- Pb(Mg<inf>1/3</inf>Nb<inf>2/3</inf>)O<inf>3</inf>-PbTiO<inf>3</inf> crystals.