Nonlinear electromechanical behaviour of KDP near its phase transition

Potassium dihydrogen phosphate (KDP) undergoes a ferroelectric phase transi tion at 123 K. The linear elastic and electromechanical properties are well known. This paper deals with simultaneous measurements of the transit time and the attenuation variations of pulsed ultrasound in parallelepiped samp les of KDP using a picosecond sampling oscilloscope, These variations are i ntroduced by low frequency electric fields, The results can be used to dete rmine complex nonlinear piezoelectric coefficients above and below the phas e transition of KDP. (C) 2000 Elsevier Science S.A. All rights reserved.