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Crystal growth and segregation were investigated in a confined vertical melt zone in which the upper solid-melt interface advanced under destabilizing and the lower interface under stabilizing thermal gradients. A technique reported by Kim et al. (1972) was used in the study. The experimental results are discussed, giving attention to interface morphology and growth rate and questions of dopant segregation. Dopant inhomogeneities formed simultaneously in both advancing interfaces can be explained on the basis of pressure induced segregation effects.

Zinc has long been recognized as essential to normal growth and development in animals and in man. Its role in regulating metabolic events at the molecular level is becoming evident, but it is not yet possible to correlate biochemical function to the pathology of deficiency. Studies by a number of investigators have indicated that feeding animals with a diet low in zinc causes an abnormal condition on skin in addition to growth retardation. These include the rats (Todd et al., 1934), mice (Day and Skidmore, 1947), swine (Kernkam and Ferrin, 1953), cattle (Miller and Miller, 1962), lambs (Ott et al., 1964) goats (Miller et al., 1964), dogs (Robertson and Burns, 1963), rabbits (Graham and Telle, 1967), squirrel monkeys (Macapinlac et al., 1967), hamsters (Boquist and Lernmark, 1969), guinea pigs (McBean et al., 1972). In man (Prasad et al., 1963) the clinical aspects of zinc deficiency are remarkably similar to those described above for animals. They consisted of growth retardation and rough skin with hyperpigmentation. These observations indicate the importance of zinc in skin metabolism.

Crystal growth method based on controlled power reduction under stabilizing thermal gradients, eliminating chemical heterogeneities

Crystal growth and segregation were investigated in a confined vertical melt zone in which the upper solid-melt interface advanced under destabilizing and the lower interface under stabilizing thermal gradients. A technique reported by Kim et al. (1972) was used in the study. The experimental results are discussed, giving attention to interface morphology and growth rate and questions of dopant segregation. Dopant inhomogeneities formed simultaneously in both advancing interfaces can be explained on the basis of pressure induced segregation effects.