JPS645993A - Production of oxide single crystal - Google Patents

Abstract

PURPOSE:To facilitate the preparation of a seed crystal and to obtain the title high- quality single crystal having less grain boundaries by heating and melting the raw material in a crucible, bringing a seed crystal of a specified size into contact with the melt, and pulling up the seed crystal while rotating the seed crystal. CONSTITUTION:The raw materials are weighed, mixed, and charged into the crucible so that the molar ratio of Li/Ta is controlled to 0.946. The mixture is heated to about 1,670 deg.C, and then cooled to about 1,650 deg.C. The seed crystal 1 of about 10mm square cut out so that the X axis is aligned with the lifting direction is then fixed to a seed holder. The seed crystal 1 is then lowered, brought into contact with the melt, and then pulled up to grow a neck part so that the neck diameter is controlled to about 6mm. The crystal is gradually grown to form a conical part 3, a body part 4 having about 90mm diameter and about 90mm thickness is then grown, the crystal is separated from the melt, and the crystal is cooled to grow an LiTaO3 single crystal. Since the diameter of the seed crystal is controlled to >=6mm square and the diameter of the neck after the start of lifting is adjusted to >=4mm phi, a high-quality single crystal, wherein the grain boundary is eliminated from the neck part and the number of grain boundaries in the body part is reduced, is obtained.