The solid state controlled growth of sulphides and selenides of Ag and Cu using crystal rotation

An improved crystal growth method for ionic-electronic mixed conductors, such as the high temperature cubic modifications of Ag₂X and Cu₂X (where X = S or Se), is presented. Ag or Cu atoms are mobile in these compounds. If the respective sulphur or selenium vapour pressure was sufficiently high at the growth surface, the growth rate was limited by the solid state chemical diffusion of Ag or Cu atoms which was controlled by the rate of the injection of the metal atoms into the compounds. The crystals were grown in a silica ampoule, held in a vertical two zone furnace and rotated at 1 rpm about the vertical axis to achieve a uniform axial temperature distribution. Nearly cylindrical single crystals of size about 3–10 mm diameter, 10–35 mm long were grown by this method.