High-temperature protonic conduction in La7P3O 18

Koji Amezawa, Yoichi Tomii, Naoichi Yamamoto

Research output: Contribution to journalConference articlepeer-review

26 Citations (Scopus)


Electrical conduction in La7P3O18 was investigated by using conductivity measurements under 0.4-5 kPa of p(H 2O), and 0.01-100 kPa of p(O2) at 500-930°C. The conductivity of La7P3O18 was considerably enhanced by Sr substitution for La. The Sr-doped La7P 3O18 had higher conductivities in wet than dry conditions, and exhibited the apparent H/D isotope effect on conductivity. From these results, it was found that La7P3O18 conducted protons dominantly by substituting Sr for La and that conducting protons were introduced through equilibrium between the material and the water vapor in ambient atmosphere. Results of conductivity measurements under various p(H 2O) and p(O2) suggested that p-type electronic conduction became significant in addition to protonic conduction with increasing temperature, increasing p(O2) and decreasing p(H2O). The conductivity behavior of Sr-doped La7P3O18 was rather similar to that of acceptor-doped LaPO4, although the conductivity of Sr-doped La7P3O18 was lower than that of acceptor-doped LaPO4.

Original languageEnglish
Pages (from-to)569-573
Number of pages5
JournalSolid State Ionics
Issue number1-4
Publication statusPublished - 2004 Nov 30
EventFourteenth International Conference on Solid State Ionics - Monterey, CA., United States
Duration: 2003 Jun 222003 Jun 27


  • LaPO
  • Oxophosphate
  • Protonic conduction


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