The Generation of Growth Dislocations by Inclusions and Growth‐Face Damages: An Experimental Study

Abstract

AbstractThe generation of growth dislocations in crystals by intentionally introduced foreign‐particle inclusions and by mechanical damaging (scratching) of the growth face is reported. The formation of dislocations is studied by in situ observation of the step pattern on the involved growth face by optical microscopy and—after growth—by X‐ray diffraction topography. This is performed on three different growth faces of orthorhombic salol (C13H10O3, melting temperature Tm = 41.5 °C) growing from the melt supercooled by 1–2 °C. The development of the growth pattern after the closure of the inclusion by overgrowing layers and after the scratching is recorded by videos. Particularly instructive is the inclusion experiment on the fast‐growing (100) face: immediately after the closure a big pyramid and fast step source appears, which dominates and sporadically overflows neighbored secondary step sources. In the sequel the big pyramid splits into a row of small hills which gradually diverge. This indicates that the associated dislocations fan out within the (010) plane of the crystal, as is confirmed by X‐ray topography. The in situ scratching of the growth face triggers the immediate appearance and fast development of a complex hill structure associated with numerous dislocations.