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Effect of Rare Earth Oxide Additives on the Phase Transformation Rates of Si 3 N 4
Author(s) -
Kitayama Mikito,
Hirao Kiyoshi,
Kanzaki Shuzo
Publication year - 2006
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.1551-2916.2006.01106.x
Subject(s) - ionic radius , phase (matter) , kinetics , oxide , materials science , rare earth , transformation (genetics) , ionic bonding , analytical chemistry (journal) , porosity , crystallography , ion , mineralogy , chemistry , metallurgy , composite material , biochemistry , physics , organic chemistry , chromatography , quantum mechanics , gene
Fully dense Si 3 N 4 sintered with rare‐earth (RE=La, Nd, Gd, and Yb) oxide additives were fabricated by hot pressing. They were mainly composed of the α‐phase, which enabled the investigation of the α–β transformation kinetics without the effect of porosity. The phase transformation kinetics was found to be linear. The activation energies for the phase transformation were 677, 546, 487, and 424 kJ/mol for RE=La, Nd, Gd, and Yb, respectively, and showed a good correlation with the ionic radii of RE atoms, which was discussed in conjunction with the segregation behaviors of RE atoms at the interface.