TY - JOUR

T1 - Conduction and Transport Numbers in Metacomposites MeWO4 ⋅ WO3 (Me = Ca, Sr, Ba)

AU - Neiman, A. Ya.

AU - Pestereva, N. N.

AU - Sharafutdinov, A. R.

AU - Kostikov, Yu. P.

N1 - This work was supported by (a) Russian Foundation for Basic Research, projects nos. 01-03-33160 and 04-03-32614; (b) scientific program “Universities of Russia,” project no. UR.06.01.027; and (c) CRDF (EK-005-XI).

PY - 2005/6/1

Y1 - 2005/6/1

N2 - The conduction and transport numbers of charge carriers for composites in the systems MeWO4-WO3 (Me = Ca, Sr, Ba) are studied as a function of the temperature and the activity of oxygen in a gas phase. The transport numbers are determined by an emf method and are estimated from dependences of conductance on the activity of oxygen in a gas phase. The deficiencies of the given procedure as applied to investigation of properties of composite phases are analyzed. The materials under study are classified with a class of metacomposites. The concentration intervals of the ionic, mixed, and electronic conductions are determined. The conduction of composites of compositions (100 − x)MeWO4 ⋅ xWO3 is predominantly ionic at x ≤ 10 (Me = Ca), x ≤ 60 (Me = Sr), and x ≤ 45 (Me = Ba). The obtained data are explained in the framework of a model that represents a composite as a distributed matrix system where a film of surface phase MeW-s with a high mobility of oxygen ions plays the role of a connected matrix. It is presumed that the surface phase MeW-s possesses double-sided surface activity (α MeW-s ≤ αWO3,αMeWO4) and a higher mobility with respect to MeWO4 and WO3. The discovered anomalies of dependences σO2−(T) and partial dependences σO2−, σel(T) are explained by a change in the stoichiometry, morphology, and the degree of connectedness of surface phase MeW-s caused by with a change in the temperature and composition of composites.

AB - The conduction and transport numbers of charge carriers for composites in the systems MeWO4-WO3 (Me = Ca, Sr, Ba) are studied as a function of the temperature and the activity of oxygen in a gas phase. The transport numbers are determined by an emf method and are estimated from dependences of conductance on the activity of oxygen in a gas phase. The deficiencies of the given procedure as applied to investigation of properties of composite phases are analyzed. The materials under study are classified with a class of metacomposites. The concentration intervals of the ionic, mixed, and electronic conductions are determined. The conduction of composites of compositions (100 − x)MeWO4 ⋅ xWO3 is predominantly ionic at x ≤ 10 (Me = Ca), x ≤ 60 (Me = Sr), and x ≤ 45 (Me = Ba). The obtained data are explained in the framework of a model that represents a composite as a distributed matrix system where a film of surface phase MeW-s with a high mobility of oxygen ions plays the role of a connected matrix. It is presumed that the surface phase MeW-s possesses double-sided surface activity (α MeW-s ≤ αWO3,αMeWO4) and a higher mobility with respect to MeWO4 and WO3. The discovered anomalies of dependences σO2−(T) and partial dependences σO2−, σel(T) are explained by a change in the stoichiometry, morphology, and the degree of connectedness of surface phase MeW-s caused by with a change in the temperature and composition of composites.

UR - https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=tsmetrics&SrcApp=tsm_test&DestApp=WOS_CPL&DestLinkType=FullRecord&KeyUT=000230551900002

UR - http://www.scopus.com/inward/record.url?partnerID=8YFLogxK&scp=23244442323

U2 - 10.1007/s11175-005-0112-1

DO - 10.1007/s11175-005-0112-1

M3 - Article

VL - 41

SP - 598

EP - 611

JO - Russian Journal of Electrochemistry

JF - Russian Journal of Electrochemistry

SN - 1023-1935

IS - 6

ER -