Dynamic Behavior of Domain Walls in Barium Titanate

Abstract

The nucleation and growth of 90\ifmmode^\circ\else\textdegree\fi{} and 180\ifmmode^\circ\else\textdegree\fi{} domains in barium titanate single crystals have been measured with optical techniques. Both types of domains nucleate as long thin wedges with an initial velocity of the order of ${10}^{4}$ cm/sec for a driving field of 5 kv/cm. For 90\ifmmode^\circ\else\textdegree\fi{} domains, detailed measurements of the nucleation rate as a function of time and field strength are given. After domains have been introduced into a crystal, their growth may be described in terms of wall motion. The 90\ifmmode^\circ\else\textdegree\fi{} wall displacement depends strongly on strains and clamping of the crystal; wall motion appears to cease for frequencies in the megacycle range, where the piezoelectric resonances of the crystal set in. The sideways growth of 180\ifmmode^\circ\else\textdegree\fi{} wedges is affected by the availability of neutralizing electric charges. Interaction of 180\ifmmode^\circ\else\textdegree\fi{} and 90\ifmmode^\circ\else\textdegree\fi{} domains may lead to 90\ifmmode^\circ\else\textdegree\fi{} wall configurations with head-to-head or tail-to-tail orientation of the polar axes.