Spherulitic crystallization of holmium tartrates in silica gels |
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Authors: | Want Basharat |
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Institution: | (1) Department of Materials Science and Engineering, University of Florida, Gainesville, FL, USA;(2) Department of Pathology, Center for the Study of Lithiasis, College of Medicine, University of Florida, Gainesville, FL, USA |
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Abstract: | Spherulites of holmium tartrate trihydrate and holmium nitro-tartrate monohydrate have been grown in silica gel medium by
making holmium nitrate to react with tartaric acid at high supersaturations. The mechanism of spherulitic growth of holmium
tartrates is discussed. The spherulitic crystallization is shown to be due to heterogeneous nucleation. In the early stages
of growth an amorphous spherical mass gets nucleated inside the gel. Crystal fibers diverge radially from the surface of the
spherical mass giving rise to a spherical polycrystalline holmium tartrate. Thermal stability of the two types of spherulites
grown in the silica gel shows that the holmium tartrate trihydrate is more stable than holmium nitro-tartrate monohydrate.
The surface morphology and internal structure of the spherulites of holmium tartrates have been studied by using scanning
electron microscopy. The results on growth kinetics are given by studying the variation of radius of spherulites as a function
of time. A non-linear time–size relations under several conditions of growth have been observed, which suggests a non-uniform
solute concentration at the crystal surface. |
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