Correlations of structural, magnetic, and dielectric properties of undoped and doped CaCu3Ti4O12
Stephan Krohns,Jun Lu,Jun Lu,Peter Lunkenheimer,V. Brize,Cécile Autret-Lambert,Monique Gervais,François Gervais,Françoise Bourée,F. Porcher,Alois Loidl +10 more
TLDR
In this article, a detailed characterization of structural, magnetic, and dielectric properties of differently tempered undoped and doped CaCu3Ti4O12 (CCTO) ceramics is presented.Abstract:
The present work reports synthesis, as well as a detailed and careful characterization of structural, magnetic, and dielectric properties of differently tempered undoped and doped CaCu3Ti4O12 (CCTO) ceramics. For this purpose, neutron and X-ray powder diffraction, SQUID measurements, and dielectric spectroscopy have been performed. Mn-, Fe-, and Ni-doped CCTO ceramics were investigated in great detail to document the influence of low-level doping with 3d metals on the antiferromagnetic structure and dielectric properties. In the light of possible magnetoelectric coupling in these doped ceramics, the dielectric measurements were also carried out in external magnetic fields up to 7 T. At low temperatures the dielectric constant shows a minor but significant dependence on the applied magnetic field. Undoped CCTO is well-known for its colossal dielectric constant in a broad frequency and temperature range. With the present extended characterization of doped as well as undoped CCTO, we want to address the question why doping with only 1% Mn or 0.5% Fe decreases the room-temperature dielectric constant of CCTO by a factor of ~100 with a concomitant reduction of the conductivity, whereas 0.5% Ni doping changes the dielectric properties only slightly. In addition, diffraction experiments and magnetic investigations were undertaken to check for possible correlations of the magnitude of the colossal dielectric constants with structural details or with magnetic properties like the magnetic ordering, the Curie-Weiss temperatures, or the paramagnetic moment. It is revealed, that while the magnetic ordering temperature and the effective moment of all investigated CCTO ceramics are rather similar, there is a dramatic influence of doping and tempering time on the Curie-Weiss constant.read more
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Colossal dielectric constants in transition-metal oxides
TL;DR: In this paper, a detailed overview and discussion of the dielectric properties of CaCu3Ti4O12 and related transition-metal oxides with large dielectoric constants is provided.
Journal ArticleDOI
Origin of colossal dielectric response in LaFeO3
M Idrees,M Idrees,Muhammad Nadeem,Muhammad Atif,Muhammad Siddique,Mazhar Mehmood,M.M. Hassan +6 more
TL;DR: In this paper, the electrical conduction and dipolar relaxation are dominated by polaronic hole hopping between Fe4+ and Fe3+ in polycrystalline LaFeO3.
Journal ArticleDOI
On the room temperature multiferroic BiFeO3: magnetic, dielectric and thermal properties
Jun Lu,A. Günther,F. Schrettle,Franz Mayr,Stephan Krohns,Peter Lunkenheimer,Andrei Pimenov,V. D. Travkin,A. A. Mukhin,Alois Loidl +9 more
TL;DR: In this paper, the authors measured the temperature dependence of the dielectric constant and loss for a single crystalline BiFeO3 and found that at room temperature the loss is substantial and strongly frequency dependent, indicating the dominance of hopping conductivity.
Journal ArticleDOI
Leading role of grain boundaries in colossal permittivity of doped and undoped CCTO
Sonia De Almeida-Didry,Cécile Autret,Anthony Lucas,Christophe Honstettre,François Pacreau,François Gervais +5 more
TL;DR: In this paper, the role of grain boundaries in the colossal permittivity of doped and undoped calcium copper titanate, CaCu3Ti4O12 (CCTO), is illustrated by a first correlation -over four orders of magnitude - between capacitance of CCTO and the capacity of grain boundary, not that of grains, deduced from the analysis of impedance measurements.
Journal ArticleDOI
Applications of CCTO supercapacitor in energy storage and electronics
Raghvendra K. Pandey,William A. Stapleton,Jitendra S. Tate,Abhijit Bandyopadhyay,Ivan Sutanto,S. Sprissler,Sidney Lin +6 more
TL;DR: In this article, the authors have shown that CCTO's permittivity and loss tangent, the two most essential dielectric parameters of fundamental importance for the efficiency of a capacitor device, are intrinsically coupled.
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