Fiber Crystal Growth From the Melt

Abstract

Cryst. Res. Technol. 341999 1 3-40The literature on melt growth of single crystalline fibers is reviewed. The paper introduces in the characteristic features and wide field of advanced applications of micro single crystals in elongated form having a small diameter in the region µm -mm. A brief historical survey is given. After that typical melt growth methods for production of fiber crystals are shown -micro zone floating (i.e. LHPG) and pulling from a die (i.e. Stepanow, EFG and micro pulling down techniques). Some selected fundamentals of the fiber growth process are described in detail, like mass and heat balance, capillary stability and segregation behaviour. In the centre of interest is the discussion of growth and analytical results obtained for various materials -oxides, mainly suitable for wave guides, lasers and nonlinear optics (sapphire, YAG, KRS-5, BBO, LiNbO 3 and further niobates etc.), eutectics for composites, semiconductors for fundamental studies, and metals for high-speed filament production. Special measures for fiber cladding, in-situ core doping and periodically ferroelectric domain adjustment are included. For the sake of completeness a look at the modern branch of polycrystalline and amorphous alloy fiber spinning and melt extrusion is taken too. In conclusion, the special suitability of fiber crystal growth for fundamental research is demonstrated.

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