Metallic state in a lime-alumina compound with nanoporous structure

Sung Wng Kim, Satoru Matsuishi, Takatoshi Nomura, Yoshiki Kubota, Masaki Takata, Katsuro Hayashi, Toshio Kamiya, Masahiro Hirano, Hideo Hosono

Research output: Contribution to journalArticlepeer-review

202 Citations (Scopus)


We report a metallic state in a nanostructured porous crystal 12CaO-7Al2O3 by incorporating electrons in the inherent subnanometer-sized cages, in which a three-dimensionally closely packed cage structure acts as an electronic conduction path. High-density electron doping (∼2 x 1021 cm-3), which was achieved by a thermal treatment in Ti metal vapor at ∼1100 °C, induces homogenization of the cage geometry to a symmetric state, resulting in an insulator-metal transition with a sharp enhancement of the electron drift mobility from ∼0.1 to 4 cm2 V-1 s-1. The results provide an approach for the realization of electroactive functions in materials composed only of environmentally benign elements by utilizing the appropriate nanostructures.

Original languageEnglish
Pages (from-to)1138-1143
Number of pages6
JournalNano Letters
Issue number5
Publication statusPublished - May 2007
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Bioengineering
  • General Chemistry
  • General Materials Science
  • Condensed Matter Physics
  • Mechanical Engineering


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