Thin film and bulk fabrication of room-temperature-stable electride C12A7:e⁻ utilizing reduced amorphous 12CaO · 7Al₂O₃(C12A7)

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• 作者：Hideo Hosono ; Sung Wang Kim ; Masashi Miyakawa ; Satoru Matsuishi ; Toshio Kamiya
• 关键词：Amorphous semiconductors ; Oxidation reduction ; Crystallization ; Glass ceramics ; Diffusion and transport ; Band structure ; Conductivity ; Nanocrystals ; Oxide glasses
• 刊名：Journal of Non-Crystalline Solids
• 出版年：2008
• 期刊代码：50_00223093
• 类别：ms
• 出版时间：1 May 2008
• 卷：354
• 期：19-25
• 页码：2772-2776
• 文件大小：486 K

摘要

Heavily electron-doped 12CaO · 7Al₂O₃(C12A7) exhibits unique electronic properties such as high electronic conductivity of 1500 S cm⁻¹ (to superconductor via metal–insulator transition) and a very small work function (2.4 eV) arising from electrons entrapped in sub-nanometer-sized cages inherent to the crystal structure. We report the efficient synthetic processes of bulk and thin film C12A7:e⁻ using the reduced C12A7 melt or a-C12A7. Solidification of the melt produced in carbon crucibles and crystallization of the reduced C12A7 glass (insulating) in vacuum yielded bulk C12A7:e⁻. It was suggested that ions work as a template to form the nano-cages in the crystallization processes. The films of C12A7:e⁻ were fabricated by the reduction treatment of crystalline C12A7 thin films with reduced a-C12A7. By applying this process, heavily electron-doped thin films of 12SrO · 7Al₂O₃ with the same crystal structure as C12A7 but a non-equilibrium phase was first realized.