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Title: Influence of La/W ratio on electrical conductivity of lanthanum tungstate with high La/W ratio

Abstract

The proton-conducting properties of lanthanum tungstates (LWOs) with high La/W ratios were investigated using electrochemical measurements and quantum chemical calculations. Single phases of LWOs with high La/W ratios (6.3≤La/W≤6.7) were synthesized by high-temperature sintering at around 1700 °C. The electrical conductivity of LWO increased with increasing La/W ratio in the single-phase region. The LWO synthesized at the optimum sintering temperature and time, and with the optimum La/W ratio gave the maximum conductivity, i.e., 2.7×10{sup −3} S cm{sup −1} with La/W=6.7 at 500 °C. Density functional theory calculations, using the nudged elastic band method, were performed to investigate the proton diffusion barrier. The results suggest that the proton diffusion paths around La sites have the lowest proton diffusion barrier. These findings improve our understanding of LWO synthesis and the proton-conducting mechanism and provide a strategy for improving proton conduction in LWOs. - Graphical abstract: The LWOs with high La/W ratios were synthesized for the first time. The optimum La/W ratio gave the maximum conductivity with La/W=6.7 at 500 °C. The proton diffusion paths were also considered with density functional theory calculations. - Highlights: • The proton-conducting properties of lanthanum tungstates (LWOs) were investigated. • Single phase LWOs with high La/W ratiosmore » (6.3≤La/W≤6.7) were synthesized successfully. • LWOs with the high La/W ratios showed high proton conductivity. • The DFT calculation suggested the lowest proton diffusion barrier in the path around La sites.« less

Authors:
;  [1];  [2];  [1];  [1]
  1. Department of Environment Systems, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwa, Chiba 277-8563 (Japan)
  2. Department of Chemical System Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)
Publication Date:
OSTI Identifier:
22658233
Resource Type:
Journal Article
Journal Name:
Journal of Solid State Chemistry
Additional Journal Information:
Journal Volume: 248; Other Information: Copyright (c) 2017 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0022-4596
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; DENSITY FUNCTIONAL METHOD; DIFFUSION BARRIERS; EXPERIMENTAL DATA; LANTHANUM TUNGSTATES; PROTON CONDUCTIVITY; SYNTHESIS; TEMPERATURE RANGE 0400-1000 K

Citation Formats

Kojo, Gen, Shono, Yohei, Ushiyama, Hiroshi, Oshima, Yoshito, and Otomo, Junichiro, E-mail: otomo@k.u-tokyo.ac.jp. Influence of La/W ratio on electrical conductivity of lanthanum tungstate with high La/W ratio. United States: N. p., 2017. Web. doi:10.1016/J.JSSC.2017.01.011.
Kojo, Gen, Shono, Yohei, Ushiyama, Hiroshi, Oshima, Yoshito, & Otomo, Junichiro, E-mail: otomo@k.u-tokyo.ac.jp. Influence of La/W ratio on electrical conductivity of lanthanum tungstate with high La/W ratio. United States. doi:10.1016/J.JSSC.2017.01.011.
Kojo, Gen, Shono, Yohei, Ushiyama, Hiroshi, Oshima, Yoshito, and Otomo, Junichiro, E-mail: otomo@k.u-tokyo.ac.jp. Sat . "Influence of La/W ratio on electrical conductivity of lanthanum tungstate with high La/W ratio". United States. doi:10.1016/J.JSSC.2017.01.011.
@article{osti_22658233,
title = {Influence of La/W ratio on electrical conductivity of lanthanum tungstate with high La/W ratio},
author = {Kojo, Gen and Shono, Yohei and Ushiyama, Hiroshi and Oshima, Yoshito and Otomo, Junichiro, E-mail: otomo@k.u-tokyo.ac.jp},
abstractNote = {The proton-conducting properties of lanthanum tungstates (LWOs) with high La/W ratios were investigated using electrochemical measurements and quantum chemical calculations. Single phases of LWOs with high La/W ratios (6.3≤La/W≤6.7) were synthesized by high-temperature sintering at around 1700 °C. The electrical conductivity of LWO increased with increasing La/W ratio in the single-phase region. The LWO synthesized at the optimum sintering temperature and time, and with the optimum La/W ratio gave the maximum conductivity, i.e., 2.7×10{sup −3} S cm{sup −1} with La/W=6.7 at 500 °C. Density functional theory calculations, using the nudged elastic band method, were performed to investigate the proton diffusion barrier. The results suggest that the proton diffusion paths around La sites have the lowest proton diffusion barrier. These findings improve our understanding of LWO synthesis and the proton-conducting mechanism and provide a strategy for improving proton conduction in LWOs. - Graphical abstract: The LWOs with high La/W ratios were synthesized for the first time. The optimum La/W ratio gave the maximum conductivity with La/W=6.7 at 500 °C. The proton diffusion paths were also considered with density functional theory calculations. - Highlights: • The proton-conducting properties of lanthanum tungstates (LWOs) were investigated. • Single phase LWOs with high La/W ratios (6.3≤La/W≤6.7) were synthesized successfully. • LWOs with the high La/W ratios showed high proton conductivity. • The DFT calculation suggested the lowest proton diffusion barrier in the path around La sites.},
doi = {10.1016/J.JSSC.2017.01.011},
journal = {Journal of Solid State Chemistry},
issn = {0022-4596},
number = ,
volume = 248,
place = {United States},
year = {2017},
month = {4}
}