Transmission electron microscopy study of polymorphism in barium gallate BaGa2O4

H. Lemmens, S. Amelinckx, G. Van Tendeloo, A. M. Abakumov, M. G. Rozova, E. V. Antipov

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12 Citations (Scopus)


Polymorphism in barium gallate BaGa2O4 was studied using electron diffraction and high resolution electron microscopy. Three modifications of BaGa2O4 with structures closely related to the high-temperature α-form were observed. The phase transitions from γ-BaGa2O4 (aγ = 18.6143(2)Å = 2√3aα, cγ = 8.6544(1) Å = cα, S.G. P63) to β-BaGa2O4 (aβ = 2aα, Cβ = cα S.G. P6 3) and to the new δ-polymorph having a monoclinic structure (aδ = cα, bδ = 2a α + bα, cδ = 2b α and β ≈ 92°, S.G. P21/c) were induced by electron beam irradiation. High resolution electron microscopy (HREM) observations allow to establish the close similarity between the structures of δ-BaGa2O4 and β-SrGa2O4. The γ→β and β-δ transitions involve a rearrangement of oxygen atoms in the BaO layers together with a tilting distortion of the tetrahedral framework. The microstructure of the δ-phase is characterised by the presence of numerous translation and orientation domains.

Original languageEnglish
Pages (from-to)653-670
Number of pages18
JournalPhase Transitions
Issue number7
Publication statusPublished - 2003
Externally publishedYes


  • Barium gallate
  • Phase transition
  • Polymorphism
  • TEM


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