Structural study of the apatite Nd8Sr2Si6O26 by Laue neutron diffraction and single-crystal Raman spectroscopy

Research output: Contribution to journalArticlepeer-review


  • Tao An
  • Alodia Orera
  • Tom Baikie
  • Jason S. Herrin
  • Ross O. Piltz
  • Tim J. White
  • Maria Sanjuan

Colleges, School and Institutes


A single-crystal structure determination of
Nd8Sr2Si6O26 apatite, a prototype intermediate-temperature
electrolyte for solid oxide fuel cells grown by the floating-zone
method, was completed using the combination of Laue neutron
diffraction and Raman spectroscopy. While neutron diffraction was in good agreement with P63/m symmetry, the possibility of P63 could not be convincingly excluded. This ambiguity was removed by the collection of orientation-dependent Raman spectra that could only be consistent with P63/m. The composition of Nd8Sr2Si6O26 was independently verified by powder X-ray diffraction in combination with electron probe microanalysis, with the latter confirming a homogeneous distribution of Sr and the absence of chemical zonation commonly observed in apatites. This comprehensive crystallochemical description of Nd8Sr2Si6O26 provides a baseline to quantify the efficacy of cation vacancies, oxygen superstoichiometry, and symmetry modification for promoting oxygen-ion mobility.


Original languageEnglish
Pages (from-to)9416-9423
Number of pages8
JournalInorganic Chemistry
Issue number17
Publication statusPublished - 20 Aug 2014