%0 Journal Article
%A Pina Martínez, Carlos Manuel
%A Becker, Udo
%A Risthaus, Peter
%A Bosbach, Dirk
%A Putnis, Andrew
%T Molecular-scale mechanismsof crystal growth in barite
%D 1998
%@ 0028-0836
%U https://hdl.handle.net/20.500.14352/57136
%X Models of crystal growth have been defined by comparing macroscopicgrowth kinetics with theoretical predictions for variousgrowth mechanisms. The classic Burton–Cabrera–Frank (BCF)theory predicts that spiral growth at screw dislocations willdominate near equilibrium. Although this has often beenobserved, such growth is sometimes inhibited, which hasbeen assumed to be due to the presence of impurities. Athigher supersaturations, growth is commonly modelled by twodimensionalnucleation on the pre-existing surface according tothe ‘birth and spread’ model. In general, the morphology of agrowing crystal is determined by the rate of growth of differentcrystallographic faces, and periodic-bond-chain (PBC) theoryrelates this morphology to the existence of chains of stronglybonded ions in the structure. Here we report tests of such modelsfor the growth of barite crystals, using a combination of in situobservations of growth mechanisms at molecular resolution with the atomic force microscope and computer simulations of thesurface attachment of growth units. We observe strongly anisotropicgrowth of two-dimensional nuclei with morphologiescontrolled by the underlying crystal structure, as well as structure-induced self-inhibition of spiral growth. Our results revealthe limitations of both the BCF and PBC theories in providing ageneral description of crystal growth.
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