Damage-induced microdomains in LiTaO3

Thin wafers of LiTaO₃ prepared from fully poled boules by mechanical cutting and polishing techniques have been found to contain defects at high concentrations (up to 10⁷/cm²). Examination of these wafers by optical and electron microscope techniques indicates that the defects are cylindrical domains 1–3 μm in diameter, within which the ferroelectric axis is inverted relative to the surrounding material. These inverted domains appear to have nucleated at screw dislocations, $\mathrm{b}\text{∥ <0001>}$ , which are observed near the axis of each domain. The results have implications for many applications of LiTaO₃, because such multidomain configurations may contribute to undesirable optical scattering, Barkhausen noise, or degraded pyroelectric response. It is suggested also that the permanent optical damage generated in LiTaO₃ by intense laser radiation may arise in part by the nucleation of similar inverted domains at dislocations generated through the action of large thermal stresses.