Transparent nanocrystalline bulk alumina obtained at 7.7 GPa and 800 ° C

Norimasa Nishiyama, Takashi Taniguchi, Hiroaki Ohfuji, Kimiko Yoshida, Fumihiro Wakai, Byung Nam Kim, Hidehiro Yoshida, Yuji Higo, Astrid Holzheid, Oliver Beermann, Tetsuo Irifune, Yoshio Sakka, Ken Ichi Funakoshi

Research output: Contribution to journalArticlepeer-review

60 Citations (Scopus)


Transparent nanocrystalline bulk alumina was obtained at 7.7 GPa and 800 C. The alumina has an average grain size of ∼150 nm and an in-line transmission of 71% for a wavelength of 640 nm and a thickness of 0.8 mm. The values of microhardness and fracture toughness were found to be 25.5 ± 0.3 GPa and 2.9 ± 0.3 MPa m1/2, respectively. The hardness value is consistent with the previously determined Hall-Petch relation and fracture toughness is independent of grain size.

Original languageEnglish
Pages (from-to)362-365
Number of pages4
JournalScripta Materialia
Issue number5
Publication statusPublished - 2013 Sept


  • Alumina
  • Hardness
  • High pressure
  • Nanocrystalline
  • Transparent


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