abstract
Development of giant-permittivity and high-tunability dielectric materials has attracted great interest because of growing demand for smaller and faster energy-storage and electronic devices. Materials such as CaCu3Ti4O12, displaying the giant dielectric permittivity due to extrinsic Maxwell-Wagner interfacial polarization effect, have previously been reported. Ferroelectric materials possessing intrinsic ionic polarization due to a phase transition to the polar state have also been indicated to possess a high tunability of the dielectric permittivity by dc electric field. Here, a class of the giant-permittivity materials based on SrTiO3 ceramics doped with up to 1% of yttrium and their processing concept, which yields the dielectric permittivity up to similar to 209,000 at 10 kHz for nitrogen sintering atmosphere, and the relative tunability up to similar to 74% under 20 kV cm(-1) for oxygen sintering atmosphere, is reported. The high tunability is proved to be due to polar clusters created at low temperatures by off-central Y3+ ions on Sr2+ sites. The giant permittivity is explained by a coupling of the polar clusters relaxation mode with the donor substitution induced electrons at low temperatures and by the Maxwell-Wagner relaxation around room temperature. Besides the fundamental understanding, this discovery opens a new development window for high frequency and low-temperature electronic and energy-storage applications. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
keywords
STRONTIUM-TITANATE CERAMICS; ELECTRICAL-CONDUCTIVITY; COLOSSAL PERMITTIVITY; ANODE MATERIALS; CACU3TI4O12; MICROSTRUCTURE; PHASE; TRANSITION; BEHAVIOR; RELAXOR
subject category
Materials Science; Metallurgy & Metallurgical Engineering
authors
Tkach, A; Okhay, O; Almeida, A; Vilarinho, PM
our authors
Oleksandr Tkach
Assistant Researcher
Olena Okhay
Post-Doc Fellowship
Paula Maria Lousada Silveirinha Vilarinho
Vice DirectorProjects
CICECO - Aveiro Institute of Materials (UID/CTM/50011/2013)
RMNE-UA-National Network of Electron Microscopy (REDE/1509/RME/2005 )
acknowledgements
This work was developed within the scope of the 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 as well as within FCT independent researcher grant IF/00602/2013 and post-doctoral grant SFRH/BD/77704/2011. Dr. Sebastian Zlotnik is acknowledged for SEM/EDS characterization, which was also supported by the project REDE/1509/RME/2005.