Synthesis, Characterization and Applications of Shaped Single Crystals

In this paper we will review techniques for the growth of single crystal mostly of insulating material which are shaped in the growth process. In particular, we will focus on the growth of single crystal fibers of optically activated materials; the emphasis will be placed on the so-called Laser Heated Pedestal Growth (LHPG) method of pulling crystalline fibers. LHPG oers a number of logistical advantages which can be exploited as a tool for materials research. Progress in the synthesis of materials using LHPG is described, as are spectroscopic techniques which are employed in characterizing the optical and physical properties of the crystal fibers obtained through this method. There has been interest on crystalline materials prepared in fiber form for a sustained period of time; this is partially because single crystal fibers occurring naturally in the form of whiskers often possess near ideal physical properties in crystallinity and in tensile strength. Earlier work addressed itself mostly to metallic materials, for example, in 1922 von Gompers [1] was successful in pulling single crystal metallic filaments directly from the melt. Later, in the 1950s, much of the work centered on the magnetic an