Crystal structure, conductivity and reversible water uptake of new layered potassium antimonates KxL(1+x)/3Sb(2-x)/3O2 (L = Ni2+, Mg2+, Co2+)
authors Smirnova, OA; Nalbandyan, VB; Avdeev, M; Medvedeva, LI; Medvedev, BS; Kharton, VV; Marques, FMB
nationality International
journal JOURNAL OF SOLID STATE CHEMISTRY
author keywords layered potassium antimonates; X-ray diffraction; Rietveld refinement; ionic conductivity; impedance spectroscopy; water absorption
keywords X LESS-THAN; IONIC CONDUCTORS; OXIDES; PHASE
abstract Novel mixed potassium antimonates K0.59Mg0.53Sb0.47O2, K0.5Ni0.5Sb0.5O2, K0.5Co0.5Sb0.5O2(rhombohedral P3-type structure), K0.56Ni0.52Sb0.48O2 and K0.86Co0.62Sb0.38O2 (hexagonal P2 type) have layered structures based on brucite-like (L,Sb)O-6/3 sheets of edge-shared octahedra and interlayer K+ cations in trigonal prismatic coordination. The preference to form P2 and P3 structures rather than closely related O3 type is dictated by the large radius of K+ and the value of unit cell parameter a, restricted by average size of the cations randomly distributed in the octahedral sites within (L,Sb)O-6/3 layer. The new phases reversibly absorb atmospheric moisture leading to the formation of hydrates with ca. 11% larger interlayer distances. The impedance spectroscopy of P2-type K0.56Ni0.52Sb0.48O2 and P3-type K0.59Mg0.53Sb0.47O2) ceramics shows relatively high ionic conductivity, presumably due to potassium cationic transport, with activation energies of 35+/-2 and 33+/-1 kJ/mol, respectively. At 573 K, the conductivity values are 0.016 S/cm for K0.56Ni0.52Sb0.48O2 and 0.021 S/cm for K0.59Mg0.53Sb0.47O2. Interaction with water vapor leads to increasing total conductivity. (C) 2004 Elsevier Inc. All rights reserved.
publisher ACADEMIC PRESS INC ELSEVIER SCIENCE
issn 0022-4596
year published 2005
volume 178
issue 1
beginning page 172
ending page 179
digital object identifier (doi) 10.1016/j.jssc.2004.07.059
web of science category Chemistry, Inorganic & Nuclear; Chemistry, Physical
subject category Chemistry
unique article identifier WOS:000227042200026
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