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H 2 O‐Catalyzed Sintering of ∼2‐nm‐Cross‐ Section Particles of MgO
Author(s) -
BERUTO DARIO,
BOTTER RODOLFO,
SEARCY ALAN W.
Publication year - 1987
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.1151-2916.1987.tb04950.x
Subject(s) - sintering , materials science , adsorption , diffusion , volume (thermodynamics) , catalysis , surface diffusion , decomposition , chemical engineering , mineralogy , chemistry , metallurgy , thermodynamics , organic chemistry , physics , engineering
MgO produced by vacuum decomposition of Mg(OH) 2 is formed as aggregates containing both open and closed pores. The surface area and the volume of the open pores, as measured by N 2 adsorption, were found to be 300 m 2 /g and 0.14 cm 3 /g, respectively. Through calorimetric and TEM studies, reported elsewhere, the initial surface area and volume of the closed pores are shown to be 550 ± 150 m 2 /g and 0.19 cm 3 /g, respectively. The samples were sintered in the presence of water at 823 K. The elimination of the closed pores and coarsening of the open pores dominate early stage sintering under the conditions studied. From the above observations, it is argued that the sintering behavior is governed primarily, not by diffusion, but by a surface step. It is postulated that the nature of the surface step is the formation of new ion layers by random fluctuations in closed pores and in smaller open pores for which edge effects are thermodynamically favorable.