Topic
Crystal habit
About: Crystal habit is a research topic. Over the lifetime, 1184 publications have been published within this topic receiving 26561 citations.
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TL;DR: In this article, the origins of fibrous crystal habits in the absence of appreciable temperature gradients and profuse non-crystallographic branching are explained, and it is shown that a plane crystal face cannot grow without suffering an instability of profile.
Abstract: To account for spherulitic crystallization from the melt, one must explain the origins (i) of fibrous crystal habits in the absence of appreciable temperature gradients and (ii) of profuse noncrystallographic branching. Attention is drawn to properties held in common by spherulite‐forming melts of various types and, in particular, to the facts that (a) they are multicomponent systems, (b) they exhibit small coefficients of self‐diffusion, and (c) they crystallize slowly. It is shown that a consequence of these properties is that a plane crystal face cannot grow without suffering an instability of profile. Analagous instabilities lead in metal crystals to a cellular interface but, because of unusual growth kinetics, instability in spherulite‐forming melts gives rise to a drastic modification of crystal habit. Bundles of discrete fibers are formed whose widths are determined by δ = D/G, D being the coefficient of self‐diffusion and G being the growth rate. δ is generally small in these systems and commensurate with the scale of crystalline disorder in the fibers. It is this circumstance that allows noncrystallographic branching to occur.
761 citations
TL;DR: In this article, the attachment energy Eatt, defined as the energy per molecule released when one slice of thickness dckl crystallizes onto a crystal face (hkl), was investigated and it was shown that the relative growth rate R of a face always increases with increasing Eatt.
630 citations
TL;DR: In this paper, a data set obtained in cirrus clouds has been examined to deduce any dependencies of the particle size spectral form or the crystal habit on the temperature, and it was found that both form of the spectra and crystal habit changed systematically with temperature, the largest change occurring between −l40 and −50°C.
Abstract: A data set obtained in cirrus clouds has been examined to deduce any dependencies of the particle size spectral form or the crystal habit on the temperature. It was found that both form of the spectra and crystal habit changed systematically with temperature, the largest change occurring between −l40 and −50°C. These findings are consistent with previously found dependencies between linear backscatter measurements and temperature. A preliminary scheme for parameterizing the cirrus particle size spectra for crystal dimensions greater than 20 μm in terms of the temperature and the ice water content is described. The visible extinction in cirrus is estimated.
495 citations
TL;DR: Very slow cooling, over several days, of solutions of complementary-DNA-modified nanoparticles through the melting temperature of the system gives the thermodynamic product with a specific and uniform crystal habit, thus establishing that DNA hybridization can direct nanoparticle assembly along a pathway that mimics atomic crystallization.
Abstract: Crystallization is a fundamental and ubiquitous process much studied over the centuries. But although the crystallization of atoms is fairly well understood, it remains challenging to predict reliably the outcome of molecular crystallization processes that are complicated by various molecular interactions and solvent involvement. This difficulty also applies to nanoparticles: high-quality three-dimensional crystals are mostly produced using drying and sedimentation techniques that are often impossible to rationalize and control to give a desired crystal symmetry, lattice spacing and habit (crystal shape). In principle, DNA-mediated assembly of nanoparticles offers an ideal opportunity for studying nanoparticle crystallization: a well-defined set of rules have been developed to target desired lattice symmetries and lattice constants, and the occurrence of features such as grain boundaries and twinning in DNA superlattices and traditional crystals comprised of molecular or atomic building blocks suggests that similar principles govern their crystallization. But the presence of charged biomolecules, interparticle spacings of tens of nanometres, and the realization so far of only polycrystalline DNA-interconnected nanoparticle superlattices, all suggest that DNA-guided crystallization may differ from traditional crystal growth. Here we show that very slow cooling, over several days, of solutions of complementary-DNA-modified nanoparticles through the melting temperature of the system gives the thermodynamic product with a specific and uniform crystal habit. We find that our nanoparticle assemblies have the Wulff equilibrium crystal structure that is predicted from theoretical considerations and molecular dynamics simulations, thus establishing that DNA hybridization can direct nanoparticle assembly along a pathway that mimics atomic crystallization.
370 citations
TL;DR: The results demonstrate that the fraction of the surface that is electrochemically active for Li(+) transportation is a key criterion for evaluating the different nanostructures of potential LIB materials.
Abstract: Major State Basic Research Development Program of China [2009CB220102]; National Science Foundation of China [20833005, 20773102, 20931160426]
347 citations