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Influence of Sodium Chloride and Dibasic Sodium Phosphate Salt Matrices on the Anatase–Rutile Phase Transformation and Particle Size of Titanium Dioxide Powder
Author(s) -
Roy Banasri,
Fuierer Paul Anton
Publication year - 2010
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.1551-2916.2009.03415.x
Subject(s) - anatase , rutile , nucleation , particle size , inorganic chemistry , salt (chemistry) , particle (ecology) , titanium dioxide , phase (matter) , materials science , chemistry , sodium , sodium hexametaphosphate , chemical engineering , metallurgy , organic chemistry , catalysis , oceanography , photocatalysis , engineering , geology
The influence of sodium chloride (NaCl) and dibasic sodium phosphate (Na 2 HPO 4 ·2H 2 O, DSP) on the phase transformation and particle size of titanium dioxide powder had been investigated. The salt matrix was shown to suppress both the amorphous to anatase transition and the anatase to rutile transition. DSP was particularly effective. Irrespective of the additives, transformation versus time curves of the anatase to rutile conversion were observed to be sigmoidal, and were interpreted in terms of a first order, nucleation‐growth controlled phenomenon. Analysis of these curves using appropriate rate laws yielded activation energies for nucleation of ∼4.3 eV for NaCl salt matrix and ∼8.6 eV for DSP salt matrix, compared with ∼3.2 eV for a sample with no salt. Activation energies for the growth or propagation stage were ∼5 and ∼8.9 eV for NaCl and DSP powders, respectively, compared with ∼3.8 eV for no salt. In the solid state, salt matrices suppressed the particle growth as well. These behaviors, in general are thought to be governed by the presence of salt impurities, especially anions chemisorbed at the surface.