Effect of isovalent substitution of La3+ in Ca-doped LaNbO4 on the thermal and electrical properties. Issue 1 (January 2019)

• Record Type: Journal Article
• Authors: Hakimova, L.; Kasyanova, A.; Farlenkov, A.; Lyagaeva, J.; Medvedev, D.; Demin, A.; Tsiakaras, P.
• Is Part Of: Ceramics international. Volume 45:Issue 1(2019)
• Page Start: 209
• Page End: 215
• Publication Date: 2019-01
• Subjects: LaNbO4 -- Proton-conducting materials -- SOFC -- Scheelite and fergusonite structures -- Protonic conductivity; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2018.09.153
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: The effect of the equimolar substitution of lanthanum in Ca-doped LaNbO4 on the functionality of (La0.5 Ln0.5 )0.99 Сa0.01 NbO4–δ (where Ln = La, Nd and Sm) is investigated in the present work. Highly dense, single-phase and of microstructurally quality ceramic samples are synthesized, using a solid state reaction method. The relation between Ln 3+ ionic radii with thermal and electrical properties is successfully revealed. It is found that the partial substitution with other lanthanides can be considered as a promising tool to suppress thermal expansion differences between low- and high-temperature modifications of lanthanum niobates; however, at the same time, the ionic conductivity decreases, which requires searching the trade-off for the optimal composition identification. Graphical abstract: Highlights: New (La0.5 Ln0.5 )0.99 Сa0.01 NbO4–δ (Ln = La, Nd and Sm) materials were obtained. (Nd/Sm)-doping suppresses the TEC differences of low- and high-temperature phases. (Nd/Sm)-doping results in a deterioration of ionic conductivity. A certain compromise in thermal and electrical properties can be reached for Ln = Nd.