abstract
Gadolinium aluminate (GdAlO3) and its calcium-substituted derivates (Gd(1-x)CaxAlO3-delta; x = 0.05, 0.10 and 0.15) are prepared via one-step mechanochemical processing of simple oxide precursors at ambient temperature. The mechanochemical reaction is accompanied by Gd2O3 phase transformation. The as-prepared and sintered ma-terials are characterized by X-ray diffraction and scanning electron microscopy. Sintering at 1450 degrees C resulted in relatively porous ceramics (with density <90 % of theoretical value) except Gd0.85Ca0.15AlO3-delta. The electrical conductivity of the sintered samples was investigated by impedance spectroscopy at 350-1000 degrees C in air. Undoped GdAlO3 ceramics exhibit low conductivity, similar to 10(-6) S/cm at 800 degrees C. Acceptor-type substitution of 5 at % of gadolinium by calcium results in-3 orders of magnitude increase in both total and bulk conductivity asso-ciated with a substantial enhancement in oxygen-ionic transport. Further doping has a limited effect on the electrical transport properties, and electrical conductivity remains nearly composition-independent in the range x = 0.05-0.15. Grain boundaries are demonstrated to have a significant contribution to the total resistivity of prepared calcium-substituted Gd(1-x)CaxAlO(3-delta) ceramics with grain sizes in the range of 1.1-1.5 mu m.
keywords
X-RAY-DIFFRACTION; HYDROTHERMAL SYNTHESIS; LUMINESCENT PROPERTIES; ELECTRONIC TRANSPORT; SOLID-ELECTROLYTE; ION CONDUCTIVITY; DOPED LAGAO3; GD2O3; NANOPARTICLES; TRANSFORMATIONS
subject category
Chemistry; Materials Science; Metallurgy & Metallurgical Engineering
authors
Fabián, M; Arias-Serrano, BI; Briancin, J; Yaremchenko, A
our authors
Aleksey Yaremchenko
Principal ResearcherProjects
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
acknowledgements
This work was developed in the scope of bilateral cooperation be-tween Slovakia and Portugal. The research was financed by the Slovak Research and Development Agency (APVV contract No. SK-PT-18-0039 and 19-0526) and by the FCT, Portugal. A.Y. acknowledges financial support within the project CICECO-Aveiro Institute of Materials (UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020) financed by national funds through the FCT/MCTES (PIDDAC) .