Crystal Structure and Oxide-Ion Conductivity of Ba1+xNd1−xInO4−x/2. Issue 13 (5th October 2017)

• Record Type: Journal Article
• Authors: Shiraiwa, Masahiro; Fujii, Kotaro; Esaki, Yuichi; Kim, Su Jae; Lee, Seongsu; Yashima, Masatomo
• Is Part Of: Journal of the Electrochemical Society. Volume 164:Issue 13(2017)
• Page Start: F1392
• Page End: F1399
• Publication Date: 2017-10-05
• Subjects: Crystal Structure -- Oxide-ion Conductivity; Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/2.0411713jes
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : BaNdInO4 is a new structure family of oxide-ion conductors. In the present work, we have investigated the crystal structure and electrical conductivity of Ba1+ x Nd1− x InO4− x /2 where x is the excess Ba content. It was found that Ba1.1 Nd0.9 InO3.95 shows (i) about 12 times higher oxide-ion conductivity at 858°C and (ii) a little lower activation energy for oxide-ion conduction than BaNdInO4 . The higher oxide-ion conductivity of Ba1.1 Nd0.9 InO3.95 is mainly ascribed to higher carrier concentration. Careful structure analyses using both the single-crystal X-ray diffraction and time-of-flight (TOF) neutron powder diffraction data enabled to determine the position of excess Ba cation and occupancy factor of O anion. It was found that the excess Ba cation substitutes for Nd cation and that oxygen vacancies exist in Ba1.1 Nd0.9 InO3.95 . The refined occupancy factor of oxygen atom 0.9829(17) indicates the higher concentration of oxygen vacancies in Ba1.1 Nd0.9 InO3.95, compared with BaNdInO4, giving higher oxide-ion conductivity in Ba1.1 Nd0.9 InO3.95 . The larger-sized Ba substitution for Nd cation makes the bottleneck size larger, leading to the lower activation energy. The bond valence-based energy landscape calculated for the refined crystal structure of Ba1.1 Nd0.9 InO3.95 at 800 and 24°C indicated two-dimensional oxide-ion diffusion in the A rare earth oxide (Nd, Ba)2 O3 unit on the bc plane.