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The Influence of ZrO 2 Additions on Al 2 O 3 Evaporation and AlN Crystal Growth by Thermal Nitridation of Al 2 O 3 – ZrO 2 Pellets
Author(s) -
You Yu,
Kato Mikako,
Ohtsuka Makoto,
Fukuyama Hiroyuki
Publication year - 2013
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/jace.12545
Subject(s) - evaporation , diffusion , materials science , nitriding , pellet , nitrogen , analytical chemistry (journal) , layer (electronics) , chemical engineering , crystallography , chemistry , nanotechnology , composite material , chromatography , physics , organic chemistry , engineering , thermodynamics
The effects of ZrO 2 additions to Al 2 O 3 were investigated to improve the evaporation rate of Al 2 O 3 for bulk AlN crystal growth. The evaporation rate of Al 2 O 3 increased concomitantly with increasing ZrO 2 concentration under a nitrogen gas stream at 2223 K. The ZrO 2 was predominantly nitrided. The nitridation of ZrO 2 kept the local oxygen partial pressure high at the pellet surface, which suppressed the nitridation of Al 2 O 3 . The nitridation of ZrO 2 caused the outward diffusion of ZrO 2 (Zr 4+ and O 2− ) in the pellet, which was accelerated further by the presence of Al 2 O 3 –ZrO 2 liquid phase in grain boundaries, leading to the prompt formation of ZrN porous layer on the pellet surface. The suppressed nitridation of Al 2 O 3 and the formation of porous ZrN layer were the reasons for the enhanced evaporation of Al 2 O 3 , leading to enhanced bulk AlN growth.