Growth mechanism of AlN crystals via thermal nitridation of sintered Al₂O₃-ZrO₂ plates

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• 作者：Hiroyuki Fukuyama^a ; ^{fukuyama@tagen.tohoku.ac.jp" class="auth_mail" title="E-mail the corresponding author} ; Mikako Kato^b ; Yu You^c ; Makoto Ohtsuka^a
• 关键词：Nitrides Growth models ; Phase equilibria ; Single crystal growth ; Oxides
• 刊名：Ceramics International
• 出版年：2016
• 出版时间：March 2016
• 年：2016
• 卷：42
• 期：4
• 页码：5153-5159
• 全文大小：2347 K

文摘

The crystal growth of AlN from aluminum oxides was studied using a thermal nitridation method. Four types of aluminum oxides, sintered Al₂O₃, ZrO₂-containing sintered Al₂O₃, and a- and c-plane sapphires, were used as a source material. As observed, millimeter-sized AlN crystal grains were successfully grown from the ZrO₂-containing sintered Al₂O₃ only at temperatures ranging from 2223 to 2323 K. The growth mechanism, including the role of ZrO₂ additive, was discussed from a thermodynamic viewpoint. The following growth model was proposed: predominant nitridation of ZrO₂ in Al₂O₃ suppresses Al₂O₃ nitridation, and the ZrO₂–Al₂O₃ liquid phase forms, which promotes the formation of Al₂O(g) and Al(g) from Al₂O₃. These Al-based gases react with CN(g) and/or N₂(g) to form AlN crystals on the Al₂O₃–ZrO₂ plate.