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Thermal Chemistry of Colloidal Titanium Dioxide
Author(s) -
SULLIVAN WILLIAM F.,
COLE SANDFORD S.
Publication year - 1959
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1959.tb14079.x
Subject(s) - anatase , rutile , nucleation , crystallite , titanium dioxide , titanium , mineralogy , inorganic chemistry , chemistry , materials science , chemical engineering , analytical chemistry (journal) , crystallography , metallurgy , photocatalysis , organic chemistry , catalysis , engineering
Chemical and physical analyses have shown that hydrous titanium dioxide, prepared from titanium sulfate solution, consists of flocculates of small anatase crystals. Water and sulfur trioxide appear to be present as adsorbed layers and in capillaries between and within the flocculates. During heating, loss of water occurs at about 150°C., loss of sulfur trioxide at about 650°C., crystallite and particle‐size growth at about 600°C., and the transformation of anatase to rutile in the range 700° to 950°C., depending on the method of preparing the samples. The kinetics of the transformation were found to be first order, following an induction time which appeared to depend on a nucleation process. Activation energies were of the order of 100 kcal. per mole and frequency factors of the order of 10 20 to 10 22 hr. ‐1 . Precision X‐ray diffraction studies showed that the anatase lattice expanded slightly before the transformation and that the initial rutile formed was expanded.