Polarity of Reticular Faces and the Thermodynamic State of the Face System of a Crystal

Abstract

A new concept into crystallography: the polarity of the reticular faces of a crystal. Reticular faces are divided into basal and additional. Basal faces, being systematic in a face system, increase only as the crystal grows. The shape of a crystal is invariant, stable within the limits of its stability, and does not affect its equilibrium state. Additional faces, on the contrary, shrink and disappear, and therefore are variable extensive parameters of the face system. They do not form their own system and associate with the basal faces, determining the variation of the face system. The polar system is nonequilibrium; it spontaneously and irreversibly transforms into the final basic face system, and is in quasi-static equilibrium. The habit of a basic crystal of an invariant shape changes during its growth according to the translational symmetry mechanism.