Temperature dependant domain structures of lithium niobate single crystals

The domain structure of lithium niobate single crystals is studied from the corresponding crystallographic characteristics at different temperatures (ranging from room temperature to the Curie temperature). The temperature dependent nature of the domain reversal and domain structures of such ferroelectric crystals have been quantitatively analyzed. Various constituent chemical bonds and oxygen octahedra (formed by these bonds) of ferroelectric lithium niobate crystals are utilized as the starting point of this work. At low temperatures, the domain structure is simplex and regular owing to the regular occupancy of constituent ions at the corresponding lattice sites (of the space group R3c). With temperature increasing, the domain structure of the ferroelectric lithium niobate crystal becomes complex, due to the complicated site occupancies of constituent ions. At high temperatures, the multi-domain is formed owing to the fact that vacant sites are energetically available for Li⁺ cations (i.e., the random location of Li⁺ cations in the crystallographic frame).