Korshykova T. Obtaining of monophase raw material and single crystals of lanthanum gallium silicate (langasite) for piezoelectric engineering

The object of study. Lanthanum gallium silicate (langasite) raw material and single crystals. The aim of study. Development of a technique for obtaining monophase raw material and single crystals of langasite with improved optical and piezoelectric characteristics. Methods and equipment. Up-to-date physical, chemical and physicochemical methods; difractometers of D-500 Siemens, Siemens-P3/PC types; ОD-103 (МОМ) derivatograph; dilatometer of Netzsch 402 ED type; KSVY-23, UR-20, SF-26, DFS-8 spectrophotometers; Polam-211, МIМ-8 microscopes; etc. Theoretical and practical results, newness. The interval of intense interection of the components (950-1450)оC is determined and investigated is the direction of mass transfer in the course of diffusive process of langasite formation in the system La2O3-Ga2O3-SiO2. The coloration of langasite single crystals is established to be caused by the reduction of Ga3+ ions; the methods of the decoloration are found. Modifier ions (Al3+ and Ti4+) are chosen and determ ined is their ratio with respect to the matrix ions leading to the crystal lattice ordering and the improvement of its optical and piezoelectric characteristics. A technique for obtaining the monophase raw material and single crystals of langasite is developed. Degree of the reduction to practic. The technique is passed to the industrial enterprises "Ukrpiezo"(Cherkassy). The sphere application. Piezoelectric engineering.