X-RAY STUDY OF THE KINETICS OF FIELD-INDUCED TRANSITION FROM THE GLASS-LIKE TO THE FERROELECTRIC PHASE IN LEAD MAGNONIOBATE

The results of the X-ray study of the evolution of (2 2 2) Bragg peak during the field induced phase transition in PMN are presented. The me asurements were performed in the ''zero field cooling'' regime. It is demonstrated that the process of the decay of the glassy phase consist s of several stages. During the first stage the kinetics is mainly det ermined by the nearly logarithmic growth of the polarization in the gl assy phase, and small embryos of the rhombohedral phase are formed. In the second stage the growth and coalescence of the polar regions and fast decay of the cubic phase are observed. As a result a bulk ferroel ectric state is formed that still contains some traces of the cubic ph ase. The results obtained allow one to make a conclusion that the low- temperature state obtained without electric field is really a glass-li ke and the application of the electric field results in the first-orde r transition. (C) 1997 Published by Elsevier Science Ltd.