Li, QianLiu, YunLuzin, VladimirStuder, Andrew J.Wan, YuhuiLi, ZhengrongNorén, LasseWithers, Ray L.Xu, Zhuo2015-12-012015-12-010021-8979http://hdl.handle.net/1885/16929In this paper, we report the phase transition behavior of ternary relaxor ferroelectric single crystals of 0.25Pb(In1/2Nb1/2)O₃-0.44Pb(Mg1/3Nb2/3)O₃-0.31PbTiO₃ subject to a uniaxial mechanical stress up to 400 MPa. The resultant in situneutron diffraction data are interpreted in terms of the polarization rotation theory and provide direct structural evidence for the stress-induced polarization rotation pathway deduced from studies of macroscopic physical properties under stress. It is suggested that an intermediate, metastable orthorhombic phase is induced above a critical pressure of ∼75 MPa. This critical stress level appears to be unaffected by sample poling although the ground states (at zero stress) for the poled and unpoled crystals are different. The critical stress level, however, does decrease with increasing temperature. The elastic behavior of the intermediate phases is also studied based on a calculation of the associated lattice strains.Q.L., Y.L., and R.L.W. acknowledge financial support from the Australian Research Council (ARC) in the form of an ARC Discovery Grant. Y.L. also acknowledges support from the ARC Future Fellowships program. The authors also thank the Australian Institute of Nuclear Science and Engineering (ANSIE) for financial support to access the national neutron facilities at ANSTO.http://www.sherpa.ac.uk/romeo/issn/0021-8979..."Publishers version/PDF may be used on author's personal website, institutional website or institutional repository" from SHERPA/RoMEO site (as at 1/12/15). Copyright 2012 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Journal of Applied Physics and may be found at https://doi.org/10.1063/1.4706563Keywords: Critical pressures; Critical stress; Elastic behavior; In-situ neutron diffraction; Intermediate phasis; Lattice strain; Orthorhombic phase; Polarization rotation; Relaxor ferroelectric; Stress-induced polarization; Structural evidence; Transition behavio2012-04-2610.1063/1.47065632016-02-24