High temperature protonic conduction in Sr-doped La2Si 2O7

Koji Amezawa, Jun Ichi Yamada, Naoto Kitamura, Yoichi Tomii, Teiichi Handa, Naoichi Yamamoto

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


Electrical conduction in the monoclinic lanthanum disilicate La 2Si2O7 was investigated in H 2O/O2 (D2O/O2) and H 2O/H2 (D2O/D2) atmospheres at 500-925°C. It was found that La2Si2O7 became to conduct protons under wet conditions by partially substituting Sr for La. From the H/D isotope effect and the partial pressure dependence of the conductivity, it was demonstrated that the protonic conduction in the Sr-doped La2Si2O7 was considerably predominant both in wet oxidizing and in wet reducing atmospheres and that the contribution of electronic conduction to the total conductivity was minor. The conductivities of the 1 mol% Sr-doped La2Si2O7 were 8 × 10-7-2 × 10-5 S cm-1 under moisturized conditions at 550-925°C, and were relatively lower than the conductivities of the acceptor-doped LaPO4 and LaBO3. The partial pressure dependencies of the conductivity of the Sr-doped La2Si 2O7, however, seemed to essentially resemble to those of the acceptor-doped LaPO4 and LaB3, indicating the similar proton dissolution and conduction mechanism in these oxoacid salts.

Original languageEnglish
Pages (from-to)341-347
Number of pages7
JournalSolid State Ionics
Issue number3-4
Publication statusPublished - 2005 Jan 31
Externally publishedYes


  • Oxoacid salt
  • Protonic conduction
  • Silicate

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics


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