Direct Correlations of Grain Boundary Potentials to Chemical States and Dielectric Properties of Doped CaCu3Ti4O12 Thin Films

Ahra Cho, Chan Su Han, Meenjoo Kang, Wooseok Choi, Jihwan Lee, Jaecheol Jeon, Sujae Yu, Ye Seul Jung, Yong Soo Cho

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Colossal dielectric constant CaCu3Ti4O12 has been recognized as one of the rare materials having intrinsic interfacial polarization and thus unusual dielectric characteristics, in which the electrical state of the grain boundary is critical. Here, the direct correlation between the grain boundary potential and relative permittivity is proposed for the CaCu3Ti4O12 thin films doped with Zn, Ga, Mn, and Ag as characterized by Kelvin probe force microscopy. The dopants are intended to provide the examples of variable grain boundary potentials that are driven by chemical states including Cu+, Ti3+, and oxygen vacancy. Grain boundary potential is nearly linearly proportional to the dielectric constant. This effect is attributed to the increased charge accumulation near the grain boundary, depending on the choice of the dopant. As an example, 1 mol % Ag-doped CaCu3Ti4O12 thin films demonstrate the best relative permittivity as associated with a higher grain boundary potential of 120.3 mV compared with 82.6 mV for the reference film. The chemical states across grain boundaries were further verified by using spherical aberration-corrected scanning transmission electron microscopy with the simultaneous electron energy loss spectroscopy.

Original languageEnglish
Pages (from-to)16203-16209
Number of pages7
JournalACS Applied Materials and Interfaces
Volume10
Issue number18
DOIs
Publication statusPublished - 2018 May 9

All Science Journal Classification (ASJC) codes

  • Materials Science(all)

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