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Segregation of impurities in crystal growth from solutions

H. V. ALEXANDRU1,*

Affiliation

  1. University of Bucharest, Romania

Abstract

Impurities have a great influence on the growth kinetic, particularly at small supersaturations. We have performed fractional recrystallization and chemical analysis of the pure and impurified KDP substance, which lead some unexpected results. Large atomic radius elements, like Ba and Sr, has segregation coefficient much higher than one and are real “poison” impurities in single crystal growth. They produce crystal lattice distortion in the first stages of growth, after seed regeneration and heavily disturb the long run growth process. The concentration of these impurities in successive fractions of recrystallized KDP from solution was measured and analysed. The concentration dependence of Ba and Sr, versus recrystallized fraction, X fit an equation similar to the distribution of impurities (or dopant) during normal, unidirectional solidification, in purification of electronic materials. It is emphasised that impurities, having segregation coefficient K>1, are “dangerous” in single crystal growth from solutions..

Keywords

KDP, Impurity segregation, Crystal growth.

Submitted at: Nov. 14, 2006
Accepted at: May 15, 2007

Citation

H. V. ALEXANDRU, Segregation of impurities in crystal growth from solutions, Journal of Optoelectronics and Advanced Materials Vol. 9, Iss. 5, pp. 1227-1231 (2007)