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A.S. Bhalla The Pennsylvania State University, Materials Research Laboratory, University Park, Pennsylvania 16802 (Received 21 June 2001; accepted 22 November 2001)

The results of the development and characterization of a new relaxor ceramic with nominal composition (x)Pb2(In,Nb)O6(1 − x)Pb(Mg1/3Nb2/3)O3 solid solution with x ⳱ 0.4 are reported. The structural characteristics, including the long-range and short-range order, forbidden reflections, and the existence of mixed ordering, were studied by transmission electron microscopy. The most prominent microstructural feature of this compound, which has composition variations in the micro- and nano-regions, was investigated. The presence of the pyrochlore phase and the complex arrangement of inclusions that originate from processing are illustrated. The electrical characteristics of the compound including pyroelectric, piezoelectric, electrostrictive and hysteresis properties are reported. Notable properties of the compound include a reduced hysteresis loop and nonlinear behavior at high field.

I. INTRODUCTION

The outstanding properties of piezoelectric crystals and ceramics can be related to the influence of morphotropic boundary phases and the development of domains. Morphotropic boundary phase is important in terms of composition, structure, and the division between at least two different crystal structures.1 In Pb(ZrxTi1−x)O3 (PZT), a morphotropic phase boundary separates the ferroelectric phase into two regions with distinct crystal structures: one is a tetragonal phase with Ti-rich composition, and the other is the rhombohedral phase with Zr-rich composition. In the region Zr/Ti ⳱ 53/47, the material has good piezoelectric properties, whereas in the solid solution regions 100/0 and 94/6, it is antiferroelectric with an orthorhombic structure, which lacks any piezoelectric property.2 There is also an abrupt change of the lattice parameters close to the composition at the morphotropic phase boundary. Another material of significant complexity and importance is (1 − x)Pb(Mg1/3Nb2/3)O3:xPbTiO3, in which the morphotropic phase boundary is at x ⳱ 0.35. This material has an overall cubic symmetry according to x-ray and neutron diffraction studies but shows a complex domain configuration, which indicates the presence of a rhombohedral phase or an intermixing of both the tetragonal and rhombohedral phases.3–6 The crystallographic parameter often seen as a determining factor in the behavior of broad relaxation peak is structural ordering. A large number of Pb-based 438

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J. Mater. Res., Vol. 17, No. 2, Feb 2002 Downloaded: 16 Mar 2015

ferroelectric compounds undergo some degree of structural ordering, which has been extensively studied.7–9 Some examples are Pb 2 (Sc,Ta)O 6 , Pb 2 (Mg,W)O 6 , and Pb(Mg1/3Nb2/3)O3, which possess complex crystal structures. Studies on the fundamental crystal structures of the ferroelectric and pyroelectric Pb2ScTaO6 have been carried out.10–13 The structure of the relaxor Pb2ScTaO6 has been refined from hig