On the nature of striae in strontium barium niobate

Abstract

Strontium barium niobate crystals were grown by the Czochralski technique. These crystals were 15–20 mm in diameter and 25 to 75 mm long. Two types of striae, designated as coarse and fine, were characterized. The coarse striae are optically dense and are spaced by 100 to 500 μm apart; the fine striae are optically less dense and spaced 5–50 μm apart. The origins of the striae are attributed to thermal fluctuations in the melt related to the control system and to rotation of the growing crystal in non-isothermal radial gradients. Analysis of the crystals indicated that the coarse striae may contain increased concentrations of sodium.