Experimental and theoretical morphology of single and twinned crystals of Li2CO3 (zabuyelite)

Crystals of lithium carbonate (monoclinic C2/c).have been synthesized from aqueous solution at room temperature and pressure. Their observed growth morphology, essentially made by {001}, {(1) over bar 01}, and {110} forms, has been compared with the theoretical one calculated applying the Hartman-Perdok method and using a formal charge potential function. Theoretical crystal equilibrium shape has also been obtained and compared with that resulting from ab initio calculations. The growth shape of the usually observed 100 contact twins is interpreted as well, on the basis of the energetic misfit of the 100 twin law and the kinetic effect due to the presence of salient and re-entrant angles at the twin original composition plane.