環境に優しい前駆体水溶液を用いたニオブ酸リチウムとニオブ酸リチウムカリウム薄膜の合成(<特集>水溶液科学に立脚したセラミックス合成プロセス)

概要

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Lithium niobate (LiNbO_3) and potassium lithium niobate (K_3Li_2Nb_5O_<15>) films can be prepared using environmentally-friendly aqueous precursor solutions. The process is reviewed by focusing on chemical properties and structure of a water soluble Li-Nb precursor molecule. The Li-Nb precursor molecule appears to be an oligomer having-O-Nb-O-Li-O-bonds with [NbO_3 (OH)_3]^<4-> octahedral structure. The water solubility of the oligomer molecule may be due to the hydroxy groups surrounding the molecule, which makes the solution alkaline. This alkaline solution can be neutralized by acetic acid. High quality LiNbO_3 and K_3Li_2Nb_5O_<15> films crystallize by heat-treatment at low temperatures. The low crystallization temperature of the LiNbO_3 film can be achieved because the precursor film contains no carbon residues, and the precursor molecule is designed to have the skeletal structure in the LiNbO_3 crystal. Micro-patterning of LiNbO_3 films are conducted by means of a coating process using neutralized aqueous precursor solution in the photolithographic technique. Aqueous precursor solutions with controlled composition can lead to the development of the processing of high quality powders and films in lead-free piezoelectric (K, Na, Li) NbO_3 ceramics and LiNbO_3 waveguides.
社団法人日本セラミックス協会の論文
2007-12-01