abstract
Magnesium-substituted europium vanadate ceramics, MgxEuVO4 +/- delta (x=0-0.5), were prepared by solid state method and characterized by XRD, SEM/EDS, dilatometry, UV-vis spectroscopy, impedance spectroscopy, and measurements of oxygen-ion transference numbers ((t) over bar (0)). Magnesium was found to substitute preferentially into vanadium sublattice of zircon-type EuVO4 with limited solubility of 5 at.%. Additions of magnesium increase slightly coefficients of thermal expansion (3.2-6.0 ppm/K at 150-400 degrees C) and have negligible effect on the optical properties. Undoped EuVO4 is predominantly an oxygen-ionic conductor with (t) over bar (0) = 0.96-0.99 at 700-900 degrees C under oxidizing conditions. Acceptor-type substitution suppresses total conductivity and oxygen-ionic transport. The variations of electrical transport properties are discussed in terms of interstitial oxygen diffusion in the parent EuVO4 and oxygen vacancy diffusion in Mg-substituted vanadate. Humidified atmosphere has negligible impact on the electrical properties of substituted ceramics but results in increased electrical conductivity of EuVO4 indicating a protonic contribution to the total electrical transport. (C) 2017 Elsevier Ltd. All rights reserved.
keywords
RARE-EARTH ORTHOVANADATES; HYDROTHERMAL SYNTHESIS; ELECTRONIC-PROPERTIES; THERMAL-EXPANSION; NANOPARTICLES; CA; CONDUCTIVITY; STABILITY; LAVO4; CEVO4
subject category
Materials Science
authors
Gayathri, TH; Yaremchenko, AA; Zakharchuk, K; Abhilash, P; Ananthakumar, S
our authors
Aleksey Yaremchenko
Principal Researcher
Kiryl Zakharchuk
PhD StudentProjects
acknowledgements
T. H. G. and P. A. thank the Council of Scientific and Industrial Research for their research fellowship. The authors thank Dr. K. P. Surendran and Mr. A. Peer Mohamed of CSIR-NIIST for their help. K.Z. and A.Y. would like to acknowledge financial support from the FCT, Portugal (project IF/01072/2013/CP1162/CT0001 and project CICECO-Aveiro Institute of Materials POCI-01-0145-FEDER-007679 (FCT ref. UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement).