Local structural arrangements and stabilities of oxygen and hydrogen-related defects in proton-conducting LaP 3O 9 were studied using first principles calculations. When an oxygen was removed from LaP 3O 9, the crystal lattice was significantly distorted. Resulting structural arrangements considerably depended on the oxygen deficient site, and phosphate ions tended to condense by sharing a corner oxygen of PO 4 tetrahedra. On the other hand, when a proton was introduced, the proton was located at the interstitial sites positioned approximately 1 away from the nearest oxygen forming an O-H bond. The LaP 3O 9 lattice was only slightly distorted even after introduction of an interstitial proton. Based on the calculation results, the stabilities of the defects under moisturized conditions was discussed.
- First principles calculations
- LaP O
- Proton conductor