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T. Onishi and T. Helgaker
Fig. 14.2 The proton
conductive ionics model
Ba 2 Zr 4 O 4 H
Fig. 14.3 The four proton
conduction paths in
Ba 2 Zr 4 O 4 H model: (a) O–O
diagonal path (A path),
(b) O–H rotation path within
Zr 4 O 4 square (B path),
(c) O–O path along y axis
(B path),
(d) three-dimensional
out-of-plane proton
conduction path (C path). The
arrows denote
hydrogen-migration direction
BaZrO 3 perovskite. One is the O–O diagonal path (A path), corresponding to proton
conduction along O–O diagonal line. The second is O–H rotation path within Zr 4 O 4
square (B path). To investigate the stable point along y axis, the proton conduction
along y axis (B path) was also considered. Note that B path is a virtual path in
proton conduction in BaZrO 3 perovskite. The last is three-dimensional out-of-plane
proton conduction path (C path), noting that the positions of the local minima along
these paths are needed in order to construct the three-dimensional paths [13, 14].
The N-doped ionics model Ba 2 Zr 4 O 3 NH was constructed to examine the effect
of N-doping on proton conduction. Referring to Fig. 14.2, nitrogen is introduced at