Cation ordering in the oxygen deficient perovskite Sr2-xLaxMg1-yTa1+yOz

Sumio Kato, Eri Ohmori, Yoshinori Suzuki, Yozo Ohshima, Mikio Sugai, Hirotsugu Takizawa, Tadashi Endo

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3 Citations (Scopus)


Perovskite-type solid solutions, Sr2-xLaxMg1-yTa1+yOz, were synthesized and cation ordering between Mg2+ and Ta5+ in the solid solutions was investigated. In the Sr2-xLaxMgTaOz system, the (NH4)3FeF6-type (1:1 order) phase was formed in the compositional range, x ≥ 0.4. However, few degree of the cation ordering between Mg2+ and Ta5+was also observed in the solid solutions, 0≤x≤0.3. These results suggest that the cation ordering between Mg2+ and Ta5+ in Sr2-xLaxMgTaOz system is affected by the average charge of A-site cation or, in other words, by the oxygen content. The 1: 2-type ordering was observed in the Sr2-xLaxMg1-yTa1+yOz solid solutions, x = 0 for y ≥ 0.3, and x ≤ 0.1 for y = 0.1, 0.2. In particular, the disappearance of the 1: 2 ordering due to small amount of La3+ substitution was observed in the stoichiometric Sr2Mg0.67Ta1.33O6-LaSrMgTaO 6 solid solution. However, in the case of the composition containing oxygen vacancy, the 1: 2 ordered phase was formed at the composition Mg/Ta = 0.8/1.2 and 0.9/1.1, although they have 20% and 35% higher Mg2+ content than in the case of Mg/Ta = 1/2, respectively. These results suggest that the 1 : 2 ordered structure is stabilized by the presence of oxygen vacancy.

Original languageEnglish
Pages (from-to)209-214
Number of pages6
JournalJournal of the Ceramic Society of Japan
Issue number3
Publication statusPublished - 1999


  • Cation ordering
  • Mg/Ta ratio
  • Oxygen defect
  • Perovskite
  • SrLaMgTaO system

ASJC Scopus subject areas

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


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