ic5b01176_si_003.cif (2.2 kB)
Proton Conduction Study on Water Confined in Channel or Layer Networks of LaIIIMIII(ox)3·10H2O (M = Cr, Co, Ru, La)
dataset
posted on 2015-09-08, 00:00 authored by Hisashi O̅kawa, Masaaki Sadakiyo, Kazuya Otsubo, Ko Yoneda, Teppei Yamada, Masaaki Ohba, Hiroshi KitagawaProton
conduction of the LaIIIMIII compounds, LaM(ox)3·10H2O (abbreviated to LaM; M
= Cr, Co, Ru, La; ox2– = oxalate) is studied in
view of their networks. LaCr and LaCo have
a ladder structure, and the ladders are woven to form a channel network. LaRu and LaLa have a honeycomb sheet structure,
and the sheets are combined to form a layer network. The occurrence
of these structures is explained by the rigidness versus flexibility
of [M(ox)3]3– in the framework with large
LaIII. The channel networks of LaCr and LaCo show a remarkably high proton conductivity, in the range
from 1 × 10–6 to 1 × 10–5 S cm–1 over 40–95% relative humidity (RH)
at 298 K, whereas the layer networks of LaCr and LaCo show a lower proton conductivity, ∼3 × 10–8 S cm–1 (40–95% RH, 298 K).
Activation energy measurements demonstrate that the channels filled
with water molecules serve as efficient pathways for proton transport. LaCo was gradually converted to LaIIICoII(ox)2.5·4H2O, which had no channel structure
and exhibited a low proton conductivity of less than 1 × 10–10 S cm–1. The conduction–network
correlation of LaCo(ox)2.5·4H2O is reported.
