Méthode de croissance en solution des monocristaux par l'addition graduelle d'un réactif

Abstract

The method generally applies to the growth of single crystals of some chemical compounds from a suitable solution. The supersaturation needed for growth is achieved by the chemical reaction of two reactants soluble in the choosen solvent one of which is added at the beginning to the solution bath, the second being gradually added during growth.The supersaturation of the solution yielded by addition one reactant is calculated for the general case of an inorganic salt obtained as a result of the neutralization reaction between the acid and the salt base. The advantages presented by this method over methods that yield the supersaturation by evaporation or by gradual cooling are discussed.A laboratory installation is described and the results obtained are presented for growth of KDP single crystals from aqueous solutions acidified with H3PO4 by gradually addition of KOH solution.KDP single crystals useful for electrooptic devices have been grown by means of this method at an absolute supersaturation of 10−4 g/ml with growth rates along the 〈001〉 axis of 2.3 mm/day. The supersaturation achieved by one addition of KOH solution is equivalent to the supersaturation obtained by cooling the solution by 0.014 °C.