Transitions in Morphotropic PMN-PT Single Crystals

Author： Amin Ahmed Ewart Lynn McLaughlin Elizabeth Robinson Harold

ISSN： 0015-0193

Source： Ferroelectrics, Vol.331, Iss.1, 2006-01, pp. : 29-33

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

Single crystals in the relaxor-ferroelectric lead magnesium niobate (PMN)-lead titanate (PT) and lead zinc niobate (PZN)-lead titanate (PT) systems provide a significant advantage for detecting and classifying objects in littoral waters. Their extremely large electromechanical coupling factor (k 33 > 0.90) and piezoelectric coefficient (d 33 > 1000 pC/N) offer both broadband and high acoustic source level capabilities. Two different transition pathways can be accessed in a morphotropic PMN-0.30PT composition. Resonance experiments on a length extensional bar fabricated from a multi-domain, [001] oriented and poled PMN- 0.30PT crystal revealed a monotonically decreasing Young's modulus as a function of temperature with a sudden stiffening near 85°C corresponding to a ferroelectric rhombohedral (F R )-ferroelectric tetragonal (F T ) transition. Quasi-static, zero field stress-strain response revealed an elastic instability of the F R near 30 MPa compression. This instability is attributed to a ferroelectric rhombohedral (F R )–ferroelectric orthorhombic (F O ) transition. A dc bias field of 0.59 MV/m stabilized the F R state up to 40 MPa compressive stresses. The implications of these results on sonar projector design and performance will be discussed.