GROWTH VELOCITIES AND DISAPPEARANCE OF FACES OF CRYSTALS

The formulae for critical absolute and relative growth velocities which govern the disappearance of faces have been derived and discussed. A face can disappear in the habit only if its velocity is greater than the critical one. Both the fast- and the slow-growing faces can disappear. It was shown that BORGSTROM's formula describes only a special case of disappearance of faces. Apart from the nearest neighbours also those farther ones influence the size and presence of faces. The calculations have been verified by the experimental results for triclinic potassium bichromate (KBC) crystals.