Diffusion Path of Oxide Ions in Apatite-type La_9.8(Si_5.7Mg_0.3)O_26.4

抄録

Densities of coherent-scattering lengths in apatite-type La_9.8(Si_5.7Mg_0.3)O_26.4 (P63/m) have been investigated at 1558 degC by Rietveld refinement and whole-pattern fitting approach based on the maximum-entropy method from neutron powder diffraction data. The Rietveld refinement suggested an interstitial oxygen atom site (0.015,0.207,0.808) accompanied by a slight improved profile fitting results. Nuclear density map derived from the MEM analyses revealed that oxide ions located at 2a site were diffused along the c-axis of the apatite system. In addition, a short range curved diffusion path through the interstitial site was clearly visualized between two oxygen atoms (O3) within the tetrahedra.