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Microstructural Characterization of High‐Thermal‐Conductivity Aluminum Nitride Ceramic
Author(s) -
Nakano Hiromi,
Watari Koji,
Hayashi Hiroyuki,
Urabe Kazuyori
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.tb00587.x
Subject(s) - materials science , grain boundary , thermal conductivity , ceramic , sintering , yttrium , nitride , amorphous solid , phase (matter) , mineralogy , aluminium , composite material , analytical chemistry (journal) , conductivity , microstructure , metallurgy , crystallography , chemistry , oxide , organic chemistry , layer (electronics) , chromatography
An aluminum nitride (AlN) ceramic with a thermal conductivity value of 272 W·(m·K) −1 , which is as high as the experimentally measured thermal conductivity of an AlN single crystal, was successfully fabricated by firing at 1900°C with a sintering aid of 1 mol% Y 2 O 3 under a reducing N 2 atmosphere for 100 h. Oxygen concentrations were determined to be 0.02 and 0.03 mass% in the grains and in the grain‐boundary phases, respectively. Neither stacking fault in the grains nor crystalline phase in the grain‐boundary regions was found by transmission electron microscopy. An amorphous phase possessing yttrium and oxygen elements was detected between the grains as thin films with a thickness of <1 nm. Because the amount of grain‐boundary phase was small, the high‐thermal conductivity of the ceramic was attributable to the low oxygen concentration in the AlN grains.