Strongly Enhanced Dielectric Response and Structural Investigation of (Sr<sup>2+</sup>, Ge<sup>4+</sup>) Co-Doped CCTO Ceramics

Boonlakhorn, Jakkree; Chanlek, Narong; Thongbai, Prasit; Srepusharawoot, Pornjuk

doi:10.1021/acs.jpcc.0c04484

Cited by 47 publications

(34 citation statements)

References 45 publications

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“…Density functional theory calculations were used to calculate the most preferential configuration for the Al and Ta dopants occupying the Ti sites of the CaCu 3 Ti 4 O 12 structure. The calculation details are described in the previous work [31]. The 3s and 3p valence states were chosen for the Al pseudopotential.…”

Section: Methodsmentioning

confidence: 99%

Enhanced giant dielectric properties and improved nonlinear electrical response in acceptor-donor (Al3+, Ta5+)-substituted CaCu3Ti4O12 ceramics

et al. 2021

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The giant dielectric behavior of CaCu3Ti4O12 (CCTO) has been widely investigated owing to its potential applications in electronics; however, the loss tangent (tanδ) of this material is too large for many applications. A partial substitution of CCTO ceramics with either Al3+ or Ta5+ ions generally results in poorer nonlinear properties and an associated increase in tanδ (to ∼0.29–1.15). However, first-principles calculations showed that self-charge compensation occurs between these two dopant ions when co-doped into Ti4+ sites, which can improve the electrical properties of the grain boundary (GB). Surprisingly, in this study, a greatly enhanced breakdown electric field (∼200–6588 V/cm) and nonlinear coefficient (∼4.8–15.2) with a significantly reduced tanδ (∼0.010–0.036) were obtained by simultaneous partial substitution of CCTO with acceptor-donor (Al3+, Ta5+) dopants to produce (Al3+, Ta5+)-CCTO ceramics. The reduced tanδ and improved nonlinear properties were attributed to the synergistic effects of the co-dopants in the doped CCTO structure. The significant reduction in the mean grain size of the (Al3+, Ta5+)-CCTO ceramics compared to pure CCTO was mainly because of the Ta5+ ions. Accordingly, the increased GB density due to the reduced grain size and the larger Schottky barrier height (Φb) at the GBs of the co-doped CCTO ceramics were the main reasons for the greatly increased GB resistance, improved nonlinear properties, and reduced tanδ values compared to pure and single-doped CCTO. In addition, high dielectric constant values (ε′ ≈ (0.52–2.7) × 104) were obtained. A fine-grained microstructure with highly insulating GBs was obtained by Ta5+ doping, while co-doping with Ta5+ and Al3+ resulted in a high Φb. The obtained results are expected to provide useful guidelines for developing new giant dielectric ceramics with excellent dielectric properties.

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Section: Methodsmentioning

confidence: 99%

Enhanced giant dielectric properties and improved nonlinear electrical response in acceptor-donor (Al3+, Ta5+)-substituted CaCu3Ti4O12 ceramics

et al. 2021

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“…The unit cell of the CCTO structure with 40 atoms was used. Details of the calculation method are reported in our previous publication [ 38 ]. For Ta or Nb, the 5 p , 6s, and 5 d states were used.…”

Section: Methodsmentioning

confidence: 99%

Effects of Charge Compensation on Colossal Permittivity and Electrical Properties of Grain Boundary of CaCu3Ti4O12 Ceramics Substituted by Al3+ and Ta5+/Nb5+

et al. 2021

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The effects of charge compensation on dielectric and electrical properties of CaCu3Ti4-x(Al1/2Ta1/4Nb1/4)xO12 ceramics (x = 0−0.05) prepared by a solid-state reaction method were studied based on the configuration of defect dipoles. A single phase of CaCu3Ti4O12 was observed in all ceramics with a slight change in lattice parameters. The mean grain size of CaCu3Ti4-x(Al1/2Ta1/4Nb1/4)xO12 ceramics was slightly smaller than that of the undoped ceramic. The dielectric loss tangent can be reduced by a factor of 13 (tanδ ~0.017), while the dielectric permittivity was higher than 104 over a wide frequency range. Impedance spectroscopy showed that the significant decrease in tanδ was attributed to the highly increased resistance of the grain boundary by two orders of magnitude. The DFT calculation showed that the preferential sites of Al and Nb/Ta were closed together in the Ti sites, forming self-charge compensation, and resulting in the enhanced potential barrier height at the grain boundary. Therefore, the improved dielectric properties of CaCu3Ti4-x(Al1/2Ta1/4Nb1/4)xO12 ceramics associated with the enhanced electrical properties of grain boundaries. In addition, the non-Ohmic properties were also improved. Characterization of the grain boundaries under a DC bias showed the reduction of potential barrier height at the grain boundary. The overall results indicated that the origin of the colossal dielectric properties was caused by the internal barrier layer capacitor structure, in which the Schottky barriers at the grain boundaries were formed.

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“…Reports related to CaCu 3 Ti 4 O 12 (CCTO) based ceramics have been continuously published. [4][5][6][7][8][9][26][27][28][29] Due to its high 3 0 , numerous researchers have proposed an internal barrier layer capacitor (IBLC) structure, consisting of semiconducting grains and insulating grain boundaries (GBs). This was the rst model used to explain the colossal dielectric response in ACu 3 Ti 4 O 12 ceramics.…”

Section: Introductionmentioning

confidence: 99%

Colossal dielectric permittivity, reduced loss tangent and the microstructure of Ca_1−xCd_xCu₃Ti₄O_12−2yF_2y ceramics

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Strongly Enhanced Dielectric Response and Structural Investigation of (Sr²⁺, Ge⁴⁺) Co-Doped CCTO Ceramics

Cited by 47 publications

References 45 publications

Enhanced giant dielectric properties and improved nonlinear electrical response in acceptor-donor (Al3+, Ta5+)-substituted CaCu3Ti4O12 ceramics

Enhanced giant dielectric properties and improved nonlinear electrical response in acceptor-donor (Al3+, Ta5+)-substituted CaCu3Ti4O12 ceramics

Effects of Charge Compensation on Colossal Permittivity and Electrical Properties of Grain Boundary of CaCu3Ti4O12 Ceramics Substituted by Al3+ and Ta5+/Nb5+

Colossal dielectric permittivity, reduced loss tangent and the microstructure of Ca_1−xCd_xCu₃Ti₄O_12−2yF_2y ceramics

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Strongly Enhanced Dielectric Response and Structural Investigation of (Sr2+, Ge4+) Co-Doped CCTO Ceramics

Cited by 47 publications

References 45 publications

Enhanced giant dielectric properties and improved nonlinear electrical response in acceptor-donor (Al3+, Ta5+)-substituted CaCu3Ti4O12 ceramics

Enhanced giant dielectric properties and improved nonlinear electrical response in acceptor-donor (Al3+, Ta5+)-substituted CaCu3Ti4O12 ceramics

Effects of Charge Compensation on Colossal Permittivity and Electrical Properties of Grain Boundary of CaCu3Ti4O12 Ceramics Substituted by Al3+ and Ta5+/Nb5+

Colossal dielectric permittivity, reduced loss tangent and the microstructure of Ca1−xCdxCu3Ti4O12−2yF2y ceramics

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Strongly Enhanced Dielectric Response and Structural Investigation of (Sr²⁺, Ge⁴⁺) Co-Doped CCTO Ceramics

Colossal dielectric permittivity, reduced loss tangent and the microstructure of Ca_1−xCd_xCu₃Ti₄O_12−2yF_2y ceramics