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Phase Relationships in the Si 3 N 4 –SiO 2 –Lu 2 O 3 System
Author(s) -
Hirosaki Naoto,
Yamamoto Yoshinobu,
Nishimura Toshiyuki,
Mitomo Mamoru,
Takahashi Junichi,
Yamane Hisanori,
Shimada Masahiko
Publication year - 2002
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.1151-2916.2002.tb00545.x
Subject(s) - lutetium , monoclinic crystal system , phase (matter) , phase diagram , materials science , orthorhombic crystal system , phase boundary , crystallography , silicon , analytical chemistry (journal) , silicon nitride , mineralogy , chemistry , crystal structure , oxide , metallurgy , yttrium , organic chemistry , chromatography
Phase relationships in the Si 3 N 4 –SiO 2 –Lu 2 O 3 system were investigated at 1850°C in 1 MPa N 2 . Only J‐phase, Lu 4 Si 2 O 7 N 2 (monoclinic, space group P 2 1 / c , a = 0.74235(8) nm, b = 1.02649(10) nm, c = 1.06595(12) nm, and β= 109.793(6)°) exists as a lutetium silicon oxynitride phase in the Si 3 N 4 –SiO 2 –Lu 2 O 3 system. The Si 3 N 4 /Lu 2 O 3 ratio is 1, corresponding to the M‐phase composition, resulted in a mixture of Lu–J‐phase, β‐Si 3 N 4 , and a new phase of Lu 3 Si 5 ON 9 , having orthorhombic symmetry, space group Pbcm (No. 57), with a = 0.49361(5) nm, b = 1.60622(16) nm, and c = 1.05143(11) nm. The new phase is best represented in the new Si 3 N 4 –LuN–Lu 2 O 3 system. The phase diagram suggests that Lu 4 Si 2 O 7 N 2 is an excellent grain‐boundary phase of silicon nitride ceramics for high‐temperature applications.