Characteristic temperatures and field effect in KTa1-xNbxO3 relaxor crystals seen via acoustic emission

[100]-oriented KTa1-xNbxO3 (x = 0.32) relaxor ferroelectric crystals have been studied by acoustic emission (AE) count rate (N) over dot in the temperature range from 200 K to 700 K. Burns temperature T-d = 620K ((N) over dot = 1.7 s(-1)) and intermediate temperature T* = 310K ((N) over dot = 3.1 s(-1)) as well as both the tetragonal-cubic TT-C = 259 K ((N) over dot = 4.0 s(-1)) and orthorhombic-tetragonal TO-T = 243K ((N) over dot = 5.0 s(-1)) phase transition temperatures have been clearly detected. T* is found to be influenced by an external DC electric field E: T* essentially decreases with a slope of approximately -60K . cm/kV accompanied with weakening in (N) over dot, as E enhances. The mechanisms of abnormal T*(E) and (N) over dot(T) dependences are discussed. Copyright (C) EPLA, 2012