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High-performance piezoelectrics benefit transducers and sensors in a variety of electromechanical applications. The materials with the highest piezoelectric charge coefficients (d33) are relaxor-PbTiO3 crystals, which were discovered two decades ago. We successfully grew Sm-doped Pb(Mg1/3Nb2/3)O3-PbTiO3 (Sm-PMN-PT) single crystals with even higher d33 values ranging from 3400 to 4100 picocoulombs per newton, with variation below 20% over the as-grown crystal boule, exhibiting good property uniformity. We characterized the Sm-PMN-PT on the atomic scale with scanning transmission electron microscopy and made first-principles calculations to determine that the giant piezoelectric properties arise from the enhanced local structural heterogeneity introduced by Sm3+ dopants. Rare-earth doping is thus identified as a general strategy for introducing local structural heterogeneity in order to enhance the piezoelectricity of relaxor ferroelectric crystals.

The development of relaxor ferroelectric single crystal technology is driven by the ability to tailor ferroelectric properties through domain engineering not achievable in polycrystalline materials. In this study, three types of domain-engineered rhombohedral Pb(In 1/2 Nb 1/2 )O 3 -Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 crystals were subjected to transverse high strain rate loading. The experimental results indicate that the domain configuration has a significant effect on the stress-induced depolarization and the associated charge released. A complete depolarization of the single-domain crystals with 3m symmetry is observed, while multidomain crystals with 4mm and mm2 symmetries retain a fraction of their initial remanent polarization. The complete depolarization of single-domain crystals is unique without transition to a non-polar phase, with a stress-induced charge density of 0.48 C/m 2 . This is up to three times higher than that of the multidomain crystals and PbZr x Ti 1-x O 3 ferroelectric ceramics that are critical for ultrahigh-power transducer applications. The main offering of this work is to propose a detailed mechanism for complete stress-induced depolarization in ferroelectric crystals which doe s not involve an intermediate transformation to a non-polar phase.

The coercive fields (EC) of Pb(In0.5Nb 0.5)O3- Pb(Mg1/3Nb2/3)O 3-PbTiO3 (PIN-PMN-PT) ternary single crystals were found to be 5 kV/cm, double the value of binary Pb(Mg1/3Nb 2/3)O3-PbTiO3 (PMNT) crystals, further increased to 6 to 9 kV/cm using Mn modifications. In addition to an increased EC, the acceptor modification resulted in the developed internal bias (Eint), on the order of ∼1 kV/cm. The piezoelectric shear properties of unmodified and Mn-modified PIN-PMN-PT crystals with various domain configurations were investigated. The shear piezoelectric coefficients and electromechanical coupling factors for different domain configurations were found to be >2000 pC/N and >0.85, respectively, with slightly reduced properties observed in Mn-modified tetragonal crystals. Fatigue/cycling tests performed on shearmode samples as a function of ac drive field level demonstrated that the allowable ac field levels (the maximum applied ac field before the occurrence of depolarization) were only ∼2 kV/cm for unmodified crystals, less than half of their coercive field. Allowable ac drive levels were on the order of 4 to 6 kV/cm for Mn-modified crystals with rhombohedral/ orthorhombic phase, further increased to 5 to 8 kV/cm in tetragonal crystals, because of their higher coercive fields. It is of particular interest that the allowable ac drive field level for Mn-modified crystals was found to be ≥60% of their coercive fields, because of the developed Eint, induced by the acceptor-oxygen vacancy defect dipoles. 2006 IEEE.

High temperature sensors are desired for down-hole well monitoring, future propulsion components, as well as improving performance and maintainability of power production facilities and other rotary combustion engines. Recently discovered high temperature oxyborate crystals showed stable piezoelectric properties and high resistivity at temperatures close to its melting point (∼ 1500°C, or 2730°F), which is very promising for high temperature sensor applications. In this paper the feasibility of using oxyborate based high temperature piezoelectric crystal (HTPC) for high temperature piezoelectric sensor applications is demonstrated. Oxyborate HTPC with various crystal cuts and vibration modes were investigated to obtain high temperature resistivity, dielectric, piezoelectric and thermal expansion properties. YCa 4O(BO3)3 crystals (YCOB) showed excellent piezoelectricity, low dielectric loss and high resistivity at temperatures up to 1000°C (> 1800°F). The measured thermal expansion coefficients of YCOB are about ∼3-8 ppm/K, depending on different orientations. High temperature accelerometers were demonstrated using YCOB HTPC at temperatures up to 1000°C with sensitivity remaining steady (∼ 2.4 pC/g) across the temperature range of 20°C - 1000°C.

Mn doped PIN-PMN-PT single crystals with diameter of 50mm have been successfully grown by the Bridgman method along >111<, >110< and >001< orientations. The effect of the acceptor dopant, Mn, on mechanical loss and other electromechanical properties was studied in comparison with pure PIN-PMN-PT single crystal under high and low electric fields. A complete set of piezoelectric, dielectric and elastic properties was derived from resonance measurements. It was demonstrated that by doping Mn, QM increases 4-5 times to 700-1000 in >001001< orientation. 2010 IEEE.

A piezoelectric Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3) single crystal traveling wave rotary motor operated in a stepping motion for cryogenic actuations was developed and characterized. This single crystal stepping motor had a torque of >= 1.5 kg cm, an excess of 1800 steps per revolution about its axis, and a power consumption of <= 2 W by using a step motion with 25% duty cycle. We then show that this single crystal motor can successfully operate at 77 K (liquid nitrogen) under a load. (c) 2008 American Institute of Physics. (c) 2008 American Institute of Physics.

In this program, Penn State, TRS Technologies, and Electronic Concepts, Inc. (ECI) worked together to perform a preliminary investigation of various issues related to the ferroelectric relaxor terpolymer for energy storage capacitors. In this program, terpolymers of P(VDF-TrFE-CFE) with different compositions were synthesized, and some of them were fabricated into thin films at ECI. The authors also characterized the electric energy density and the AC and DC resistivities of the terpolymers; investigated the graceful failure and improvement in the breakdown strength and the graceful failure of the terpolymer films; and designed and fabricated a high-voltage and high-speed discharge circuit. The results are summarized in this report. (11 tables, 13 figures), Prepared in collaboration with TRS Technologies, Inc., State College, PA, and Electronic Concepts, Inc.

A small, linear-type, piezoelectric ultrasonic cryomotor has been developed for precision positioning at extremely low temperatures (greater than or equal to-200 degreesC). This cryornotor consists of a pair of Pb(Mgl(1/3)Nb(2/3))O-3-PbTiO3 single crystal stacks, which are piezoelectrically excited into the rotating third-bending mode of the cryomotor stator's center, which in turn drives a contacted slider into linear motion via frictional forces. The performance characteristics achieved by the cryornotor are: (i) a maximum linear speed of >50 mm/s; (ii) a stroke of >10 mm; (iii) a driving force of >0.2 N; (iv) a response time of similar to29 ms; and (v) a step resolution of similar to20 nm. (C) 2005 American Institute of Physics.