engleski

Shape relaxation during equilibrium-like growth of spherical cuprous selenide single crystals

The spherical equilibrium-like shaped single crystals of nonstoichiometric cuprous selenide have been grown using the modified Ohachi's method at about 30 K below its roughening temperature, T_R(111) = 830 K. The growth has been performed under conditions of a constant volume growth rate. During the growth of partly faceted ((111) facets) and partly rounded crystal, the sphere diameter, the diameters of the facets and the heights of the facets were measured in situ, using a CCD camera. Two growth features have been observed. First, there is the exponential-like shape relaxation toward its equilibrium form with a single relaxation time constant of about 1200 minutes and second, there are facet size oscillations with period of about 100 minutes, superimposed on the shape relaxation. The facet size oscillation accompanied with the facet height time stepping appears to be the basic feature of the growth of faceted crystal of a nearly equilibrium shape. The oscillation feature, being probably the consequence of the facet pinning potential, seems to have certain similarity with the recently reported stepping-like growth mode of ^4He solid/liquid interface at 2 mK.

cuprous selenide; nearly equilibrium crystal shape; Ohachi's method; facet size oscillations; stepping-like growth mode

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