N. M. Polozkov

The growth of multicomponent oxide single crystals by stepanov's technique

Abstract This paper is concerned with the problems of growing multicomponent oxide compounds with the structures of pseudoilmenite, tetragonal potassium-tungsten bronze, garnet, silenite, and evlitine from the melt by Stepanovs technique. Single crystals of LiNbO 3 , Sr x Ba 1− x Nb 2 O 6 , Ca 3 (VO 4 ) 2 , Bi 12 SiO 20 , Bi 12 GeO 20 , Bi 4 Ge 3 O 12 and and Nd 3 Ga 5 O 12 were grown in an apparatus using RF heating of platinum crucibles in air. Platinum dies with plane and rectangular shapes were used. Stepanovs technique made it possible to increase several times the rates of solidification needed to obtain optically homogeneous single crystals. Optimum crystallographic directions of pulling of a crystallizing substance from various-profile dies were experimentally determined for crystals from various symmetry groups. An association of the shape of a growing crystal with the structural defects was established according to the Curie principle. The experimental data provided support for the growth of profiled multicomponent single crystals.

Growth of barium tungstate crystals

The paper concerns the growth of BaWO4 crystals by Czochralski method and modified Stepanov technique. The influence of different factors, such as type of die, form of crystallization front, melt composition, thermal conditions, on the real structure of the material was investigated. The origin of the defects in Czochralski-grown and bulk-profiled barium tungstate is discussed. It is shown that the striation-free bulk-profiled crystals of high optical quality can be produced by new developed technique. Comparison of the crystallization conditions for Czochralski method and Stepanov technique is carried out.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.