Hindawi Publishing Corporation Advances in Condensed Matter Physics Volume 2013, Article ID 382140, 5 pages http://dx.doi.org/10.1155/2013/382140 Research Article Temperature Dependence of Electrical Properties and Crystal Structure of 0.29Pb(In 1/2 Nb 1/2 )O 3 –0.44Pb(Mg 1/3 Nb 2/3 )O 3 –0.27PbTiO 3 Single Crystals Qian Li, 1 Yun Liu, 1 Andrew Studer, 2 Zhenrong Li, 3 Ray Withers, 1 and Zhuo Xu 3 1 Research School of Chemistry, he Australian National University, ACT 0200, Australia 2 Bragg Institute, Australian Nuclear Science and Technology Organization (ANSTO), NSW 2232, Australia 3 Electronic Materials Research Laboratory, Xi’an Jiaotong University, Shanxi 7100049, China Correspondence should be addressed to Yun Liu; yliu@rsc.anu.edu.au Received 31 May 2013; Revised 3 October 2013; Accepted 7 October 2013 Academic Editor: Jianhua Hao Copyright © 2013 Qian Li et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. We characterized the temperature dependent (25–200 C) electromechanical properties and crystal structure of Pb(In 1/2 Nb 1/2 )O 3 - Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 single crystals using in situ electrical measurement and neutron difraction techniques. he results show that the poled crystal experiences an addition phase transition around 120 C whereas such a transition is absent in the unpoled crystal. It is also found that the polar order persists above the maximum dielectric permittivity temperature at which the crystal shows a well-deined antiferroelectric behavior. he changes in the electrical properties and underlying crystal structure are discussed in the paper. 1. Introduction Lead-based relaxor ferroelectric single crystals (RFSCs) have been intensely studied over recent decades due to their exceptional electromechanical coupling performance. Typi- cal RFSCs include binary systems Pb(Zn 1/3 Nb 2/3 )O 3 -PbTiO 3 (PZN-PT) and Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 (PMN-PT) [1, 2], as well as a ternary system, Pb(In 1/2 Nb 1/2 )O 3 -Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 (PIN-PMN-PT), which possess enhanced properties in terms of high Curie temperature and coer- cive ield . he origin of high piezoelectricity of RFSCs has long been an important issue. In this regard a widely accepted theory, proposed by Fu and Cohen [3], is the polarization rotation mechanism, the essence of which is that the polariza- tion vectors can rotate freely within a lattice plane instead of being restricted to certain directions. his theory is supported by the observations of intermediate phases near the mor- photropic phase boundary (MPB), for example, monoclinic and phases (space group Cm and Pm, resp.) [4]. On the other hand, the structure evolution of RFSCs under external ields of thermal, electrical, and/or mechanical stress is another important issue. From a viewpoint of application, as many piezoelectric devices are employed under a multi- ield coupled environment, their electromechanical behavior usually deviates from a simple linear constitutive relationship, and as a result, those devices may sufer from failures that are unexpected based on individual factors. herefore, it is of great importance to understand the structural evolution of RFSCs that governs their macroscopic properties using in situ techniques. In this paper, we aim to study the electromechanical prop- erties and crystal structure evolution with temperature for Pb(In 1/2 Nb 1/2 )O 3 -Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 single crys- tals, via in situ single crystal neutron difraction in conjunc- tion with electrical characterization methods. he result leads to a good understanding of the phase transition behaviour in this material and associated RFSCs.