Synthesis and characterization of sodium cation-conducting Na-x(MyL1-y)O-2 (M = Ni2+, Fe3+; L = Ti4+, Sb5+

authors	Smirnova, OA; Kharton, VV; Marques, FMB
nationality	International
journal	BOLETIN DE LA SOCIEDAD ESPANOLA DE CERAMICA Y VIDRIO
author keywords	sodium cationic conductor; impedance spectroscopy; air humidity; thermal expansion; ceramic microstructure
keywords	OXYGEN-ION CONDUCTORS; FORMER SOVIET-UNION; SOLID ELECTROLYTES; O2 STRUCTURE; OXIDES; NASICON; ELECTROCHEMISTRY; CERAMICS; SENSOR
abstract	The Na+-conducting ceramics of layered Na0.8Ni0.4Ti0.6O2, Na0.8Fe0.8Ti0.2O2, Na0.8Ni0.6Sb0.4O2 (structural type O3) and Na0.68Ni0.34Ti0.66O2 (P2 type) with density higher than 91% were prepared via the standard solid-state synthesis route and characterized by the impedance spectroscopy, thermal analysis, scanning electron microscopy, structure refinement using X-ray powder diffraction data, measurements of Na+ concentration cell e.m.f., and dilatometry. The conductivity of antimonate Na0.8Ni0.6Sb0.4O2, synthesized first time, was found lower than that of isostructural Na0.8Ni0.4Ti0.6O2 due to larger ion jump distance between Na+ sites. At temperatures above 420 K, transport properties of sodium cation-conducting materials are essentially independent of partial water vapor pressure. In the low-temperature range, the conductivity reversibly increases with water vapor pressure varied in the range from approximately 0 (dry air) up to 0.46 atm. The sensitivity to air humidity is influenced by the ceramic microstructure, being favored by increasing boundary area. The average thermal expansion coefficients of layered materials at 300-1173 K are in the range (13.7-16.0)x 10(-6) K-1.
publisher	SOCIEDAD ESPANOLA CERAMICA VIDRIO
issn	0366-3175
year published	2004
volume	43
issue	3
beginning page	679
ending page	685
web of science category	Materials Science, Ceramics
subject category	Materials Science
unique article identifier	WOS:000222515800014