Preparation of monodispersed colloidal particles

The latest advances in oriented attachment controlled morphosynthesis and crystal growth of various technically important inorganic materials have been reviewed with the focus on how to generate inorganic micro-/nanostructured materials based on the so-called oriented attachment mechanism. The overview about the basic crystallization principles nowadays falls into two types, i.e., one is the classical crystal growth mode, which is via atom-by-atom additions to an existing nucleus or dissolution of unstable phases and reprecipitation of more stable phases, and the other occurs through particle based aggregation modes involving the process of mesoscopic transformation. The systematic analysis of the particle based aggregation mechanism of oriented attachment in controllable synthesis of functional inorganic materials will be described in particular. Several fashions of attachment are undertaken in the already explored reaction systems, with nanoparticles or nanoribbons as primary building units to form 1D, 2D or 3D structures, and heterostructures. The mechanism of oriented attachment could happen in systems with addition of organic additives or without, demonstrating that organic additives are not the essential factor for this kind of growth mode, which shed new light to intensive understanding of this particular phenomenon. With organic additives, i.e., reactions in organic solvents or in aqueous solution, oriented attachment events can occur too. Current developments in oriented attachment, including the basic principles and potentials with specific examples, indubitably reinforce the understanding of detailed interaction mechanisms between inorganic nanoparticles and their subsequent high order self-assembly mechanism, which are definitely promising for rationally designing various kinds of inorganic materials with ideal hierarchy, controllable length scale, and structures in solution-based systems.

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Recent advances in oriented attachment growth and synthesis of functional materials: concept, evidence, mechanism, and future

Directing the Architecture of Cuprous Oxide Crystals during Electrochemical Growth

Particular solutions of the diffusion equation, with radial symmetry, in three and in two dimensions, found originally by Rieck, represent the diffusion field around a spherical or cylindrical new phase, growing from a negligible initial radius in an initially uniform medium, maintaining equilibrium conditions at the growing surface. The resulting diffusion field is most simply described by saying that the radial gradient is the same as that of the corresponding potential problem with fixed boundaries, multiplied by a factor exp (- r 2 /4 Dt ), where r is radius, D diffusivity, t time. The result is applied to phase growth controlled by the diffusion of heat, solute, or both together. It differs appreciably from the static approximation unless the supercooling, or the supersaturation and the solubility, are small.

C. W. Bunn

Papers

Crystal growth from solution. II. Concentration gradients and the rates of growth of crystals