Growth modes in vapour-phase prepared orthorhombic molybdenum trioxide crystals

Vapour-phase growth of orthorhombic molybdenum trioxide has been carried out under various growth conditions. It is found that the Miller-index of c-axis-related crystal planes increases with rise in degree of vapour supersaturation in the order of {0 0 1} < {1 0 2} < {2 0 3} < {1 0 1} < {3 0 2} < {2 0 1} < {4 0 1}; some of these planes are observed for the first time. In high supersaturation growths, natural crystal planes associated to c-direction, change to convex curved growth fronts, whereas in low supersaturation cases, low Miller-index planes (left-hand side of the above order) persist. Formations of curvy steps and terraces on {0 1 0} planes are correlated to growth temperature and supersaturation. Growth mechanisms/oscillation are also addressed on the basis of the current findings. (C) 1999 Elsevier Science B.V. All rights reserved.