Amorphous Tl1-xCuiCl solid solution and their crystallization studied by optical absorption spectroscopy

Amorphous solid solutions are obtainable for the binary Tl1-xCuxCl system by means of two-sources evaporation onto 77 K substrates. Their annealing behavior has been studied for a him with x similar to0.4 by optical absorption spectroscopy. In the as-prepared film an appreciable amount of Cu 3d states is localized with the energies lying above the upper valence bands. On annealing the him, Cu+ ions migrate to form clusters in the amorphous environment, with their size depending on the annealing temperature. The lowest annealing temperature at which the clusters are formed lies near the crystallization temperature of amorphous CuCl. On further annealing at higher temperatures, the clusters grow until the amorphous environment has a particular atomic composition ratio suggestive of a new, novel compound, which exhibits a well defined crystallization temperature, 300 K. (C) 2000 Elsevier Science S.A. All rights reserved.