Defect Structure of the High-Dielectric-Constant Perovskite Cacu3ti4o12

Abstract

Using transmission electron microscopy (TEM) we studied CaCu3Ti4O12, an intriguing material that exhibits a huge dielectric response, up to kilohertz frequencies, over a wide range of temperature. Neither in single crystals, nor in polycrystalline samples, including sintered bulk- and thin-films, did we observe the twin domains suggested in the literature. Nevertheless, in the single crystals, we saw a very high density of dislocations with a Burger vector of [110], as well as regions with cation disorder and planar defects with a displacement vector 1/4[110]. In the polycrystalline samples, we observed many grain boundaries with oxygen deficiency, in comparison with the grain interior. The defect-related structural disorders and inhomogeneity, serving as an internal barrier layer capacitance (IBLC) in a semiconducting matrix, might explain the very large dielectric response of the material. Our TEM study of the structure defects in CaCu3Ti4O12 supports a recently proposed morphological model with percolating conducting regions and blocking regions.

To be published in Physical Review B 21 pages, 8 figures

References in corpus (5)

• A first-principles study of the structure and lattice dielectric response of CaCu{3}Ti{4}O{12}
• Extrinsic models for the dielectric response of CaCu{3}Ti{4}O{12}
• Charge transfer in the high dielectric constant materials CaCu3Ti4O12 and CdCu3Ti4O12
• Epitaxial Thin Films of the Giant-Dielectric-Constant Material CaCu_3Ti_4O_{12} Grown by Pulsed-laser Deposition
• Temperature dependent total scattering structural study of CaCu3Ti4O12

Cited by in corpus (6)

• Colossal dielectric constants in single-crystalline and ceramic CaCu3Ti4O12 investigated by broadband dielectric spectroscopy
• Nanoparticles of the giant dielectric material, CaCu3Ti4O12 from a precursor route
• Effect of calcium stoichiometry on the dielectric response of CaCu3Ti4O12 Ceramics
• Ti-rich and Cu-poor grain-boundary layers of CaCu${}_3$Ti${}_4$O${}_{12}$ detected by x-ray photoelectron spectroscopy
• Commensurate structural modulation in the charge- and orbitally-ordered phase of the quadruple perovskite (NaMn${}_3$)Mn${}_4$O${}_{12}$
• Impedance spectroscopy and its application