Microstructure, chemical composition, and dielectric response of CaCu3Ti4O12 ceramics doped with F, Al, and Mg ions
O.Z. Yanchevskii,
O.I. V'yunov,
T.O. Plutenko,
A.G. Belous,
V.V. Trachevskii,
I. Matolínová,
K. Veltruská,
V. Kalinovych,
Ye Lobko
Affiliations
O.Z. Yanchevskii
Dept. Solid State Chemistry, V. I. Vernadsky Institute of General and Inorganic Chemistry of the National Academy of Science of Ukraine, Acad. Palladin Ave. 32/34, 03142, Kyiv, Ukraine
O.I. V'yunov
Dept. Solid State Chemistry, V. I. Vernadsky Institute of General and Inorganic Chemistry of the National Academy of Science of Ukraine, Acad. Palladin Ave. 32/34, 03142, Kyiv, Ukraine; Corresponding author.
T.O. Plutenko
Dept. Solid State Chemistry, V. I. Vernadsky Institute of General and Inorganic Chemistry of the National Academy of Science of Ukraine, Acad. Palladin Ave. 32/34, 03142, Kyiv, Ukraine
A.G. Belous
Dept. Solid State Chemistry, V. I. Vernadsky Institute of General and Inorganic Chemistry of the National Academy of Science of Ukraine, Acad. Palladin Ave. 32/34, 03142, Kyiv, Ukraine
V.V. Trachevskii
G.V. Kurdyumov Institute of Metal Physics of the National Academy of Science of Ukraine, Acad. Vernadskii Ave. 36, 03680, Kyiv, Ukraine
I. Matolínová
Dept. Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 180 00, Prague, Czech Republic
K. Veltruská
Dept. Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 180 00, Prague, Czech Republic
V. Kalinovych
Dept. Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 180 00, Prague, Czech Republic
Ye Lobko
Dept. Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 180 00, Prague, Czech Republic
Ceramics with nominal chemical composition CaCu3Ti4O12 (CCTO), CaCu3Ti3.96Al0.04O11.96F0.04 (CCTOAF), and Ca0.98Mg0.08Cu2.94Ti3.96Al0.04O11.96F0.04 (CCTOMAF) were prepared by the solid-state reactions technique. Using SEM, EDX, XPS, EPR, NMR, and complex impedance spectroscopy, the microstructure, elements distribution, chemical composition of grains and grain boundaries, and the dielectric response of ceramics were investigated. In the ССТО, CCTOAF, and CCTOMAF series, the average grain size increases, the degree of copper segregation at the grain boundaries is inversely related to grain size, and the dielectric loss decreases from 0.071 to 0.047 and 0.030, respectively, while dielectric permittivity ε′ at 1 kHz is 5.6 × 104, 7.1 × 104, and 4.3 × 104, respectively. Additives of Al, Mg, F and milled particles (ZrO2, Al2O3, and SiO2) can either partially introduce into the perovskite structure or form low-melting eutectics at the grain boundaries, causing abnormal grain growth. The presence of copper ions in various oxidation states, as well as evidence of exchange spin interactions between them, was confirmed in all samples.
