Comprehensive first-principles study of AgGaO2 and CuGaO2 polymorphs

Issei Suzuki, Yuki Iguchi, Chiyuki Sato, Hiroshi Yanagi, Naoki Ohashi, Takahisa Omata

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1 Citation (Scopus)


The electronic structures of delafossite-type ¡-AgGaO2 and ¢-NaFeO2-type ¢-AgGaO2 were calculated based on density-functional theory using the local density approximation functional including the Hubbard correction. We compared the electronic structures of ¡- and ¢-AgGaO2 with previously reported electronic structures of ¡- and ¢-CuGaO2. We found that the AgAg distances in ¡- and ¢-AgGaO2 are almost the same as the CuCu distances in ¡- and ¢-CuGaO2, respectively, despite the ionic radius of Ag+ being larger than that of Cu+, because the frameworks of their crystal structures are determined by the linkages of GaO6 octahedra in the ¡- phase and GaO4 tetrahedra in the ¢-phase. It is indicated that transfer of electrons in Ag 4d states of AgGaO2 can occur between Ag atoms more easily than in Cu 3d states of CuGaO2 because high-electron-density regions surrounding Ag atoms are closer to each other than those of Cu atoms. This resulted in larger dispersion of the valence band of AgGaO2 than CuGaO2 for both ¡- and ¢-phases. We propose that the ratio of ionic radii of the monovalent and trivalent cations, rAI=rBIII, can provide an indication of the dispersion of the valence band of delafossite-type and ¢-NaFeO2-type ternary oxide semiconductors.

Original languageEnglish
Pages (from-to)339-347
Number of pages9
JournalJournal of the Ceramic Society of Japan
Issue number6
Publication statusPublished - 2019 Jun


  • Delafossite-type structure
  • First-principles calculation
  • Ternary oxide semiconductors
  • X-ray photoelectron spectroscopy
  • ¢-NaFeO-type structure

ASJC Scopus subject areas

  • Ceramics and Composites
  • Chemistry(all)
  • Condensed Matter Physics
  • Materials Chemistry


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