Formation of bidomain structure in lithium niobate plates by the stationary external heating method

Abstract

The method of development of the bidomain structure in single crystalline lithium niobate plates based on the creation of a given temperature gradient distribution through a sample thickness by stationary heating is considered. Heating the LiNbO₃ plate, which is placed between two silicon plates, is implemented by light energy emitted by lamps of the photonic annealing setup, which is absorbed by silicon. The scheme of the technological cell provides the formation and control over heat fluxes penetrating a ferroelectric plate and forming temperature gradients required for the controlled formation of two domains with the opposite polarization vectors (a head-to-head domain structure). The efficiency of light absorption for the formation of heat sources, which can be used for symmetric and asymmetric heating, which determines the position of the conditional surface with a zero temperature gradient and, consequently, a domain boundary position, is confirmed experimentally. In the LiNbO₃ plate with a thickness of 1.6 mm and length 60 mm, a symmetric bidomain structure with oppositely directed polarization vectors is formed. The dependence of the bending strain of a console-clipped sample on electric voltage is studied in the temperature range −300 to +300 V; the strain amplitude is more than 35 μm. The high linearity and repeatability of the electric voltage-bending strain characteristic is shown.