Giant dielectric permittivity and high tunability in Y-doped SrTiO3 ceramics tailored by sintering atmosphere

• Type: Article in International Scientific Journal
• Date: 2017

Authors

Tkach, A (Author) Other; Okhay, O (Author) Other; Almeida, A (Author) FCUP; Vilarinho, PM (Author) Other

Journal

Title: Acta Materialia

Vol. 130

Pages: 249-260

ISSN: 1359-6454

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 0 Citations

Scopus - 0 Citations

Other information

Authenticus ID: P-00M-KP2

DOI: 10.1016/j.actamat.2017.03.051

Abstract (EN): 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.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 12