“Generation III” Piezoelectric Single Crystals Developed by Solid-State Single Crystal Growth Method

Crystallographically engineered Relaxor-PT single crystals, specifically PMN-PT (Generation I) and PIN-PMN-PT/PMN-PZT (Generation II), offer much higher piezoelectric and electromechanical coupling coefficients (d33>1,500 pC/N, k33>0.9), when compared to polycrystalline PZT-5H ceramics (d33>600 pC/N, k33>0.75). Recently Ceracomp Co., Ltd. (www.ceracomp.com) has developed the solid-state single crystal growth (SSCG) technique and successfully fabricated Gen III PMN-PZT single crystals modified with acceptors or donors. The piezoelectric constants (d33) of (001) Gen III PMN-PZT single crystals were measured to be higher than 4,000 pC/N and thus about two times higher than those of PMN-PT/PZN-PT (Gen I) and PIN-PMN-PT/PMN-PZT (Gen II) single crystals. The Gen III PMN-PZT single crystals have been firstly applied to single crystal-epoxy composites, ultrasonic transducers, piezoelectric sensors, and piezoelectric actuators. In this paper we introduce the development of Gen III PMN-PZT single crystals, piezoelectric composites and multilayer single crystal actuators.

Properties of high-temperature poling ferroelectric crystals congruent solid solution LiNb0.5Ta0.5O3

Lithium niobate and lithium tantalate are among the most important and most widely used materials in acousto-optics and acoustoelectronics. These materials have high values of piezoelectric constants, which makes it possible to use these materials as actuators; however, their use is limited by the thermal instability of a lithium niobate crystal and the low Curie temperature (TC) of a lithium tantalate crystal. LiNb(1-x)TaxO3 crystals have to overcome the aforementioned limitations of individual compounds.Crystals LiNb0.5Ta0.5O3 were grown by the Czochralski method, of good quality. Comparative studies of the features of high-temperature single domainization of LiNb0.5Ta0.5O3 crystals have been carried out. The main differences in the technological regimes for single-domainization of congruent LiNb0.5Ta0.5O3 crystals from congruent LiNbO3 crystals are demonstrated. The parameters of high-temperature electrodiffusion processing LiNb0.5Ta0.5O3 crystals are presented, which make it possible to obtain single-domain crystals for further study of their physical properties.

High-temperature poling treatment of congruent ferroelectric LiNb0.5Ta0.5O3 solid solution single crystals

Lithium niobate and tantalate are among the most important and widely used materials of acoustooptics and acoustoelectronics. They have high piezoelectric constants enabling their use as actuators. Their use is however restricted by the thermal instability of lithium niobate crystals and the low Curie temperature TC of lithium tantalate crystals. Overcoming these drawbacks typical of some compounds is possible by growing LiNb1-xTaxO3 single crystals. Good quality LiNb1-xTaxO3 single crystals have been grown using the Czochralsky technique. High-temperature poling process of LiNb1-xTaxO3 single crystals has been studied. The main differences between the process modes required for poling of congruent LiNb1-xTaxO3 single crystals and congruent LiNbO3 single crystals have been demonstrated. Parameters of high-temperature electric diffusion processing of LiNb1-xTaxO3 single crystals that provide for singledomain crystals for further study of physical properties have been reported.

Inhomogenous Amorphous Content and Enhanced Piezoelectric Properties in Bi12TiO20-based Composite Ceramics

Bi12TiO20-based composite ceramics were prepared by sintering a mixture of presynthesized Bi12TiO20 and a second phase around the melting point of Bi12TiO20. These ceramics can exhibit direct as well as inverse piezoelectricity without electrical polarization, and become competitive piezoelectric material with high depoling temperature and stable thermal behavior. However, their piezoelectric constants were, in general, relatively low and do not remain consistent for both the symbol and magnitude over the entire surface. To prevent the permeation of melting Bi12TiO20 into substrate and thus create the inhomogenous amorphous content, samples were sintered on Al2O3 (0001) single crystal substrate. Compared to samples sintered on Al2O3 ceramics, piezoelectric coefficient (d33) of these samples was increased by 80%. Moreover, the symbol of d33 is identical on the whole surface. Here, the enhanced piezoelectricity might be ascribed to increased alignment of distorted BiO5 polyhedra in amorphous Bi12TiO20 phase. These results provided a method to improve the piezoelectric properties of Bi12TiO20-based ceramics and provided some inspiration for further development of Bi12TiO20-based ceramics suitable for practical applications.

Exploring the anion chemical space of Ln2OF2−xClxH2 (Ln = Y, La, Gd): a model of electroelastic material with high mechanical sensitivity and energy harvesting

The focus of our research was to design a novel inorganic material that would combine enhanced compressibility with high piezoelectric constants.

The Influence of the Sintering Temperature on the Properties of the 0.98Pb(Zr1-xTix)O3 - 0.02La(Fe3+0.5, Nb5+0.5)O3 Ceramic Systems

The ferroelectric solid solutions described by a general formula 0.98Pb(Zr1-xTix)O3 – 0.02La(Fe3+0.5, Nb5+0.5)O3 have been obtained by solid state reaction technique, where x assumes the following values: 0.42, 0.48 and 0.58. The structure of these ferroelectric compositions has been investigated in detail using X-ray diffraction analysis (XRD) and Scanning Electron Microscopy (SEM). The results obtained by XRD have evidenced that all obtained samples have a perovskite structure. The influence of the sintering temperature on the degree of incorporation of the elements in the solid solution have been studied too. The dielectric and piezoelectric constants have been determined and the influence of temperature on obtained values are presented and discussed. The performed experimental results have pointed out that the materials are characterized by a high anisotropy. Furthermore, the obtained values of the electromechanical coupling factor (kp) is situated between 0.40÷0.65 depending on the composition and the sintering temperature too.

Thermodynamic and thermoelastic properties of wurtzite-ZnS by density functional theory

In the present paper, we provide a detailed theoretical investigation on fundamental thermodynamic, thermomechanical, and electronic properties of wurtzite ZnS between 0–20 GPa and 0–2000 K, obtained by ab initio density functional theory and the B3LYP functional. Several properties, such as phonon dispersion relations, elastic and piezoelectric constants, and thermodynamic and thermoelastic behaviors were calculated and reported. The analysis of the data via volume-integrated third-order Birch-Murnaghan fitting resulted in K0 = 72.17(4) GPa, K′ = 3.87(1), and V0 = 85.781(1) Å3 at T = 0 K. The Born criteria for the mechanical stability of the mineral phase showed that wurtzite is unstable above about 19 GPa in static conditions. We calculated a direct bandgap for wz-ZnS of 4.86 eV at zero compression, which became an indirect one by increasing pressure above 17 GPa. The results are in good agreement with the experimental and theoretical ones reported in the literature, and further extend the knowledge of an important zinc sulfide phase, for both geological and industrial applications.

Vibration analysis and pull-in instability behavior in a multiwalled piezoelectric nanosensor with fluid flow conveyance

In this work, surface/interface effects for pull-in voltage and viscous fluid velocity effects on the dimensionless natural frequency of fluid-conveying multiwalled piezoelectric nanosensors (FC-MWPENSs) based on cylindrical nanoshells is investigated using the Gurtin–Murdoch surface/interface theory. The nanosensor is embedded in a viscoelastic foundation and subjected to nonlinear van der Waals and electrostatic forces. Hamilton’s principle is used to derive the governing and boundary conditions and is also the assumed mode method used for changing the partial differential equations into ordinary differential equations. The influences of the surface/interface effect, such as Lame’s constants, residual stress, piezoelectric constants and mass density, are considered for analysis of the dimensionless natural frequency with respect to the viscous fluid velocity and pull-in voltage of the FC-MWPENSs.

Structure, dielectric and piezoelectric properties of Pb[(Zr0.45,Ti0.5)(Mn0.5,Sb0.5)0.05]O3 ceramics

This study describes structure, dielectric and piezoelectric properties of Pb[(Zr0.45,Ti0.5)(Mn0.5,Sb0.5)0.05]O3 (PZT-PMS) ceramics prepared by conventional mixed-oxide route and sintered at up to 1180?C. The prepared ceramics was characterized by X-ray diffraction and scanning electron microscopy. The piezoelectric constants, dielectric constant, Young?s modulus and electromechanical factors were measured in broad temperature range. The results showed that the PZT-PMS ceramics is composed of tetragonal and rhombohedral phases and has the average grain size of about 1 ?m. The Pb[(Zr0.45,Ti0.5)(Mn0.5,Sb0.5)0.05]O3 ceramics has excellent dielectric and piezoelectric properties for wide practical applications. Thus, planar coupling factor of 0.70, poled dielectric constant of 8215, the Curie temperature of 345?C and dielectric loss of 6% were attained in the PZT-PMS ceramics sintered at 1180?C.