Investigation of micro- and nanoscale barrier layer capacitance mechanisms of conductivity in CaCu3Ti4O12via scanning probe microscopy technique

Ivanov, Maxim; Amaral, F.; Khomchenko, V. A.; Paixão, J. A.; Costa, L.C.

doi:10.1039/c7ra06385g

Cited by 36 publications

(29 citation statements)

References 24 publications

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“…This figure supports recent measurements for the current density as higher charge density equates to higher current density. This argument also explains the scanning electron microscopy measurements that show a higher charge density in the grain boundary region and how the permittivity of samples typically increases when the grain boundary resistance decreases …”

supporting

confidence: 91%

“…The blue line displays measurements of current at different points through a CCTO sample (data adapted from ref. ). The different regions of the sample are labeled.…”

mentioning

confidence: 97%

“…Initial explanations for the mechanism behind colossal permittivity focused on Schottky‐type effects . However, these descriptions cannot simultaneously account for high loss factors, low breakdown voltages, low resistance over grain boundaries, nor how colossal permittivity scales with system size . Colossal permittivity ranges by orders of magnitude in different materials, but also in samples of the same stoichiometry .…”

mentioning

confidence: 99%

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The Fundamental Mechanism Behind Colossal Permittivity in Oxides

Taylor

Davies

et al. 2019

Advanced Materials

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Colossal permittivity materials exhibit extreme polarization in an applied electric field, providing applications in electronics and energy transmission. Understanding the atomic‐scale mechanism behind colossal permittivity remains a challenging task and is key to optimizing materials with this property. The fundamental mechanism of colossal permittivity is reported and, using CaCu3Ti4O12 as an example, it is attributed to the formation of an unusual metallic interface between the grain and grain boundary materials (CaCu3Ti4O12 and CuxO (x = 1, 2), respectively), not created by oxygen vacancies as is normally the case in oxide materials. This metallic layer around the grain forms confined shells of charge that pool on one side when under an applied field, which results in colossal permittivity. A route towards enhancing colossal permittivity is explained by means of manipulating the interface properties, as well as altering sample geometries. A methodology to artificially engineer colossal permittivity metamaterials is also shown.

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supporting

confidence: 91%

“…The blue line displays measurements of current at different points through a CCTO sample (data adapted from ref. ). The different regions of the sample are labeled.…”

mentioning

confidence: 97%

mentioning

confidence: 99%

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The Fundamental Mechanism Behind Colossal Permittivity in Oxides

Taylor

Davies

et al. 2019

Advanced Materials

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“…Herein, ε′ increases with growth of grains; suggesting that, giant dielectric behavior in this region might be related to space charge or interfacial polarization originating from grain boundary regions . On the other hand, the low dielectric permittivity at high frequencies is primarily originated from the bulk grain response …”

Section: Resultsmentioning

confidence: 93%

“…The peaks are more pronounced for the CT/deficient CC X T Y O ceramics, which as previously seen present the highest electrical relaxations. All these experimental results reveal that ε′′ at low frequency should be due to interface polarization from grain boundaries, while the dielectric relaxation peaks at high frequency region can be associated to the bulk or grain effects, attributed to phenomena associated with accumulation of space charges or point defects …”

Section: Resultsmentioning

confidence: 96%

Deficient or excessive CuO‐TiO₂ phase influence on dielectric properties of CaCu₃Ti₄O₁₂ ceramics

Gelfuso

Uribe

Thomazini

2018

Int J Applied Ceramic Tech

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The influence of the CuO-TiO 2 phase (CT) on dielectric properties of the CCTO ceramic was investigated. CaCu X Ti Y O 12 (CC X T Y O) powders were prepared based on the coprecipitated method, where 2.70 ≤ x ≤ 3.30 and 3.25 ≤ y ≤ 4.75. XRD patterns confirmed the presence of CCTO and also the secondary phases as CuO, TiO 2 , and CaTiO 3 for each sample and aided in its quantification. Scanning Electron Microscopy (SEM) shows secondary phases evolution in the grain boundaries, and its influence on size and morphology of the grains. Impedance spectroscopy measurements showed that the ceramics with lower amount of CuO and TiO 2 phases (CT/deficient ceramics) exhibited the highest ε′ values (2.1 × 10 4 at 1 kHz for CC 2.9 T 3.75 O ceramic). Also, CT/deficient ceramics showed lower tanδ values (0.090 at 1 kHz for CC 2.9 T 3.75 O ceramic) than ceramics prepared with excessive CuO-TiO 2 phase (0.241 at 1 kHz for CC 3.1 T 4.25 O ceramics). The deficiency of CuO and TiO 2 phases associated with high percentage of CCTO and CaTiO 3 phases resulted in ceramics with the higher ε′ values.

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Core–Shell Engineering of Conductive Fillers toward Enhanced Dielectric Properties: A Universal Polarization Mechanism in Polymer Conductor Composites

et al. 2022

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Flexible dielectric and electronic materials with high dielectric constant (k) and low loss are constantly pursued. Encapsulation of conductive fillers with insulating shells represents a promising approach, and has attracted substantial research efforts. However, progress is greatly impeded due to the lack of a fundamental understanding of the polarization mechanism. In this work, a series of core–shell polymer composites is studied, and the correlation between macroscopic dielectric properties (across entire composites) and microscopic polarization (around single fillers) is investigated. It is revealed that the polarization in polymer conductor composites is determined by electron transport across multiple neighboring conductive fillers—a domain‐type polarization. The formation of a core–shell filler structure affects the dielectric properties of tpolymer composites by essentially modifying the filler‐cluster size. Based on this understanding, a novel percolative composite is prepared with higher‐than‐normal filler concentration and optimized shell's electrical resistivity. The developed composite shows both high‐k due to enlarged cluster size and low loss due to restrained charge transport simultaneously, which cannot be achieved in traditional percolative composites or via simple core–shell filler design. The revealed polarization mechanism and the optimization strategy for core–shell fillers provide critical guidance and a new paradigm, for developing advanced polymer dielectrics with promising property sets.

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Investigation of micro- and nanoscale barrier layer capacitance mechanisms of conductivity in CaCu₃Ti₄O₁₂via scanning probe microscopy technique

Abstract: In this work we disclose micro- and nanoscale origins of the unusually high dielectric constant characteristic of CaCu3Ti4O12 (CCTO) ceramic by using the Scanning Probe Microscopy (SPM) technique.

Cited by 36 publications

References 24 publications

The Fundamental Mechanism Behind Colossal Permittivity in Oxides

The Fundamental Mechanism Behind Colossal Permittivity in Oxides

Deficient or excessive CuO‐TiO₂ phase influence on dielectric properties of CaCu₃Ti₄O₁₂ ceramics

Core–Shell Engineering of Conductive Fillers toward Enhanced Dielectric Properties: A Universal Polarization Mechanism in Polymer Conductor Composites

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Investigation of micro- and nanoscale barrier layer capacitance mechanisms of conductivity in CaCu3Ti4O12via scanning probe microscopy technique

Abstract: In this work we disclose micro- and nanoscale origins of the unusually high dielectric constant characteristic of CaCu3Ti4O12 (CCTO) ceramic by using the Scanning Probe Microscopy (SPM) technique.

Cited by 36 publications

References 24 publications

The Fundamental Mechanism Behind Colossal Permittivity in Oxides

The Fundamental Mechanism Behind Colossal Permittivity in Oxides

Deficient or excessive CuO‐TiO2 phase influence on dielectric properties of CaCu3Ti4O12 ceramics

Core–Shell Engineering of Conductive Fillers toward Enhanced Dielectric Properties: A Universal Polarization Mechanism in Polymer Conductor Composites

Contact Info

Product

Resources

About

Investigation of micro- and nanoscale barrier layer capacitance mechanisms of conductivity in CaCu₃Ti₄O₁₂via scanning probe microscopy technique

Deficient or excessive CuO‐TiO₂ phase influence on dielectric properties of CaCu₃Ti₄O₁₂ ceramics