High electromechanical coupling piezoelectrics: relaxor and normal ferroelectric solid solutions

International Center for Actuators and Transducers, Materials Research Laboratory, The Pennsylvania State University, University Park, PA 16802, USA
Solid State Ionics 01/1998; DOI: 10.1016/S0167-2738(98)00017-4

ABSTRACT A new category of piezoelectric ceramics with very high electromechanical coupling was discovered in a lead zinc niobate–lead titanate solid solution in a single crystal form. The maximum coupling factor k33 reaches 95%, which corresponds to the energy conversion rate twice as high as the conventional lead zirconate titanate ceramics. This paper reviews the previous studies on superior piezoelectricity in relaxor ferroelectric: lead titanate solid solutions and on the possible mechanisms of this high electromechanical coupling.

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    ABSTRACT: Effects of compressive stress applied perpendicular to electric field on dielectric properties of (1−x)Pb(Zr 1/2 Ti 1/2 )O 3 −(x)Pb(Zn 1/3 Nb 2/3 )O 3 (x = 0.1–0.5) ceramics were investigated. The results showed that the superimposed compression stress had pronounced effects on the dielectric properties of PZT-PZN ceramics. With increasing compressive stress the dielectric constant of the ceramics decreased, while the dielectric loss tangent increased. The observations were mainly interpreted in terms of competing influences of the domain switching through non-180° domain walls, clamping of domain walls, and de-aging mechanisms. Interestingly, the observed changes of the dielectric properties with the perpendicular compressive stress were generally similar to those under the parallel stress.
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    ABSTRACT: The solid solution between the normal ferroelectric and relaxor ferroelectric of 0.7(Pb(Zr 1/2 Ti 1/2 )O 3 ) – 0.3(Pb(Zn 1/2 Nb 2/3 )O 3 was synthesized by the columbite method. After sintering, the ceramics were investigated as a function of annealing time. Properties of the ceramics were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), dielectric spectroscopy, and hardness tester. The results indicated that dielectric constant of the annealed samples was enhanced. In addition, hardness values of the annealed samples were also improved.
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    ABSTRACT: The superior piezoelectric and dielectric properties of the relaxor based piezoelectric single crystals (PMN-PT) render them as prime candidates for Navy sonar detectors as well as in broad band medical ultrasonic imaging devices. Production of phased array probes utilizing these types of high performance ceramics requires dicing these crystals to arrays with pitches of less than the desired wavelength, ranging from tens to hundreds of micrometers. However, the relaxor based single crystals are very brittle with fracture toughness of about a third to a half that of typical PZT ceramics (0.4-0.8 MPa m ). Excessive chipping and cracking, either during the cutting or poling process, have been reported as major hurdles in processing, leading to spurious resonance and degradation of the distance resolution. In addition, residual stress from the cutting process could be major reliability degradation if it is not well quantified and minimized. In this work, we experimentally analyzed the machining induced damage in a group of Lead Magnesium Niobate-Lead Titanate solid solution single crystal {(1-x)[Pb(Mg1/3Nb2/3)O3]-x[PbTiO3] (PMN-PT)} under simulated process parameters for cutting speeds and down feeds. The machined surfaces are examined by non-contact optical profilometer for planarity and roughness, scanning electron microscopy for subsurface damage, and by micro-raman spectroscopic analysis and X-ray diffraction analysis to uncover machining induced phase transformations. The analysis reveals the preferred process parameters for minimal machining induced damages.