Abstract
The initial growth of copper-sulfide formed on the (100), (110) and (111) faces of Cu single crystals in H2S-H2 gas mixture was studied by electron diffraction and electron microscopy. Sulfidation was carried out to form a sulfide film about 1000 Å in thickness at 30°C to 400°C in 500 ppm to 100% H2S.
Main results obtained are as follows:
(1) The sulfide formed on the specimen was alpha (low) chalcocite Cu2S. Not as usual, the chemisorbed layer formed on a clean surface of Cu was regarded as the immediate substrate for the growth of Cu2S, and the following epitaxial relationships were recognized, Cu(100)\varparallelCu2S(012), Cu(110)\varparallelCu2S(001), Cu(111)\varparallelCu2S(001).
(2) The above epitaxial relationships were well maintained at a thinner sulfide film and a higher sulfidation temperature.
(3) It was considered that Cu2S first nucleated as a small orthohexagonal or hexagonal cell and later it grew into a large orthorhombic cell.
(4) Initial sulfidation rate varied with the crystal face and was greater at the (111) face than at (100) and (110) faces.
