New Insights into the Effect of Nonstoichiometry on the Electric Response of Strontium Titanate Ceramics

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abstract

The effect of nonstoichiometry (Sr/Ti ratio from 0.995 to 1.02) on the bulk and grain boundary contributions to the electrical response of strontium titanate (STO) ceramics is investigated. Nonstoichiometric STO exhibits lower electrical resistivity than its stoichiometric counterpart. This decrease is systematic for both Ti- and Sr-excess and with a greater effect on the grain boundary resistivity compared to bulk. Moreover, systematic variations with the degree of nonstoichiometry are observed for bulk and grain boundary conductivity, activation energy, and capacitance. These changes are correlated with a high concentration of point defects and induced by the nonstoichiometry, increasing the charge carrier concentration. As a result, nonstoichiometry can be used to tailor the microstructure and properties of strontium titanate, particularly grain boundary properties.

keywords

BOUNDARY DEFECT CHEMISTRY; ACCEPTOR-DOPED TITANATES; ABNORMAL GRAIN-GROWTH; IMPEDANCE SPECTROSCOPY; DIELECTRIC RESPONSE; SRTIO3; LAYER; SR0.97TI1-XFEXO3-DELTA; CONDUCTIVITY

subject category

Chemistry; Science & Technology - Other Topics; Materials Science

authors

Amaral, L; Tkach, A; Vilarinho, PM; Senos, AMR

our authors

foto Ana Maria de Oliveira e Rocha Senos

Ana Maria de Oliveira e Rocha Senos

Collaborator
no photo

Luis Miguel de Almeida Amaral

foto Oleksandr Tkach

Oleksandr Tkach

Assistant Researcher
foto Paula Maria Lousada Silveirinha Vilarinho

Paula Maria Lousada Silveirinha Vilarinho

Vice Director

Groups

G2 - Photonic, Electronic and Magnetic Materials

Projects

CICECO - Aveiro Institute of Materials (UID/CTM/50011/2013)

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. The authors acknowledge as well the financial support from the Foundation for Luso American Development (FLAD), Portugal. FCT is also acknowledged for financial support by Luis Amaral (SFRH/BD/40927/2007 and SFRH/BPD/97453/2013) and Alexander Tkach (IF/00602/2013). The authors thank Rainer Schmidt for the helpful discussion of the IS results and Ian Reaney for TEM data acquisition and analysis.

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Publication Details

type
Journal Article
year
2019
journal
JOURNAL OF PHYSICAL CHEMISTRY C
volume
123
publisher
AMER CHEMICAL SOC
issn
1932-7447
issue
1
digital object identifier
10.1021/acs.jpcc.8b10438
web of science article identifier
WOS:000455561100076

Journal Metrics (JCR 2019)

Journal Impact Factor
4.189
Journal Impact Factor (5 yrs)
4.404
category normalized journal percentile
64.576

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