A Model for Evaluating the Crystallinity Quality of Single Crystals Grown by the Floating Zone Technique

Abstract

The floating zone technique is a popular method for crystal growth of nonconventional superconductors and magnetic materials. However, the quality must be characterized with particular care with respect to their actual crystallinity since not everything grown by floating zone method is a single crystal. In this paper, the molten-zone sensitive material LiCoPO 4 has been grown by the floating zone method using Co(NO 3 ) 2 •6H 2 O and CoO precursors, respectively, abbreviated as LCP N and LCP O . The grown materials are characterized regarding their chemical composition, phase purity, crystal perfection, and orientation. In order to optimize crystal growth and quantitatively characterize its crystallinity quality, the development factor (V) has been proposed to determine the growth rate of the grains, while the orientation deviation factor (𝜹) for assessing the quality of the grown crystals. The development factors V for LCP N and LCP O are calculated to be 0.05 and 0.09, respectively, indicating that the grains of LCP O develop faster than those of LCP N . At the same time, the orientation deviation factor of LCP O exceeds that of LCP N (𝜹(LCP O ) = 2.00, 𝜹(LCP N ) = 0.77) suggesting a higher quality for the latter. This model provides significant guidance for the evaluation of other materials grown by the floating zone method.