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Initial Sintering of Submicrometer Titania Anatase Powder
Author(s) -
Hébrard JeanLuc,
Nortier Patrice,
Pijolat Michèle,
Soustelle Michel
Publication year - 1990
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.1151-2916.1990.tb05094.x
Subject(s) - anatase , sintering , porosity , limiting , diffusion , particle (ecology) , oxygen , materials science , surface diffusion , particle size , kinetic energy , chemistry , chemical engineering , thermodynamics , mineralogy , metallurgy , composite material , catalysis , physics , organic chemistry , mechanical engineering , oceanography , adsorption , photocatalysis , quantum mechanics , engineering , geology
Measurements of surface area reduction of TiO 2 anatase powder (of initially 100 m 2 · g −1 ) were carried out for various partial pressures of water and oxygen at 823 K. The kinetic equation obtained for the experimental rates has the formulation r = k[P H2O ] 1/α [ P O2 ] 1/β where α and β are equal to 2 and ‐12, respectively. A mechanistic model involving six consecutive elementary steps was developed, in which hydroxyl species play a dominant role. No geometrical assumption is required. The general expression of the deduced theoretical rates has the same form as previously given. The comparison between the experimental and the predicted rates points out that the rate‐limiting step is the surface diffusion of hydroxyl species. This model can easily be used for any other compounds, for particle growth, and for porosity elimination.