Lithium niobate, LiNbO₃, is a very important material for optical and other applications. It has been widely used in applications such as electric waveguides, memory elements, acoustic wave transducers, optical amplitude modulators, second harmonic generators, etc. Its structural type is one of the four most common "typical structures" for double oxides of ABO₃ stoichiometry and it can be considered as a disordered ilmenite lattice. Recently, it has also been possible to prepare a metastable LiNbO₃ phase with the ideal ilmenite structure.