Influences of Sr2+ Doping on Microstructure, Giant Dielectric Behavior, and Non-Ohmic Properties of CaCu3Ti4O12/CaTiO3 Ceramic Composites

Jumpatam, Jutapol; Putasaeng, Bundit; Chanlek, Narong; Thongbai, Prasit

doi:10.3390/molecules26071994

Cited by 13 publications

(6 citation statements)

References 41 publications

(92 reference statements)

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“…Colossal dielectric permittivity of ceramic oxides with very large dielectric constant (ε > 10 4 ) has been extensively studied for use in electronics applications, especially for capacitive-based devices such as ceramic capacitors [1][2][3][4][5][6][7][8][9][10][11]. Since the colossal dielectric permittivity of CaCu 3 Ti 4 O 12 (CCTO) ceramics was reported by Subramanian, et al [12], many simple and complex oxides such as NiO, ZnO, TiO 2 , SnO 2 , BiFeO 3 , and CCTObased ceramics, have been investigated [1][2][3][13][14][15][16][17][18][19][20][21][22][23][24].…”

Section: Introductionmentioning

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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Section: Introductionmentioning

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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“…Even though the excessive TiO 2 phase was not detected in the XRD patterns for all ceramics, the variation in compositions of the CuO and/or TiO 2 ratios in an ACu 3 Ti 4 O 12 compound usually affects the dielectric and electrical properties [ 6 , 10 , 24 , 45 , 47 , 48 , 49 ]. Thus, we first investigated the dielectric properties of the NYCTO + xTiO 2 ceramics at around room temperature (30 °C).…”

Section: Resultsmentioning

confidence: 99%

“…The crystal structures of the sintered sample were characterized using X–ray diffraction (XRD, PANalytical, EMPYREAN, Shanghai, China), scanning electron microscopy (MiniSEM, SEC, SNE–4500 M), field emission scanning electron microscopy (FIB–FESEM,) with energy dispersive X–ray (EDX) spectroscopy and X–ray photoemission spectroscope (XPS, PHI5000 Versarobe II, ULVAC–PHI, Chigasaki, Japan). Comprehensive details were provided in our previous works [ 12 , 21 , 44 , 45 , 46 ].…”

Section: Methodsmentioning

confidence: 99%

Significantly Improved Colossal Dielectric Properties and Maxwell—Wagner Relaxation of TiO2—Rich Na1/2Y1/2Cu3Ti4+xO12 Ceramics

et al. 2021

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In this work, the colossal dielectric properties and Maxwell—Wagner relaxation of TiO2–rich Na1/2Y1/2Cu3Ti4+xO12 (x = 0–0.2) ceramics prepared by a solid-state reaction method are investigated. A single phase of Na1/2Y1/2Cu3Ti4O12 is achieved without the detection of any impurity phase. The highly dense microstructure is obtained, and the mean grain size is significantly reduced by a factor of 10 by increasing Ti molar ratio, resulting in an increased grain boundary density and hence grain boundary resistance (Rgb). The colossal permittivities of ε′ ~ 0.7–1.4 × 104 with slightly dependent on frequency in the frequency range of 102–106 Hz are obtained in the TiO2–rich Na1/2Y1/2Cu3Ti4+xO12 ceramics, while the dielectric loss tangent is reduced to tanδ ~ 0.016–0.020 at 1 kHz due to the increased Rgb. The semiconducting grain resistance (Rg) of the Na1/2Y1/2Cu3Ti4+xO12 ceramics increases with increasing x, corresponding to the decrease in Cu+/Cu2+ ratio. The nonlinear electrical properties of the TiO2–rich Na1/2Y1/2Cu3Ti4+xO12 ceramics can also be improved. The colossal dielectric and nonlinear electrical properties of the TiO2–rich Na1/2Y1/2Cu3Ti4+xO12 ceramics are explained by the Maxwell–Wagner relaxation model based on the formation of the Schottky barrier at the grain boundary.

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“…tor. These results are extremely hard to replicate in other varieties of GD oxides, including CCTO and other related compounds [2,48,49], CuO [6], co-doped NiO [50], and La2-xSrxNiO4 ceramics [7]. Furthermore, the excellent dielectric parameters exhibited by the LuNTO-1 ceramics form one of the most interesting Ln 3+ /Nb 5+ (or Ta 5+ ) co-doped TiO2 systems [22,23,26,[28][29][30].…”

Section: Giant Dielectric Propertiesmentioning

confidence: 95%

“…Notably, the LuNTO-1 ceramic exhibited a low tanδ value of approximately 0.007 at 1 kHz alongside a high ε' of approximately 7.55 × 10 4 , where ∆ε ε 30 • C /(%) ≤ ±15% in the temperatures between −55 • C and 200 • C, thereby meeting the basic requirement for its application in an X9Rtype ceramic capacitor. These results are extremely hard to replicate in other varieties of GD oxides, including CCTO and other related compounds [2,48,49], CuO [6], co-doped NiO [50], and La 2−x Sr x NiO 4 ceramics [7]. Furthermore, the excellent dielectric parameters exhibited by the LuNTO-1 ceramics form one of the most interesting Ln 3+ /Nb 5+ (or Ta 5+ ) co-doped TiO 2 systems [22,23,26,[28][29][30].…”

Section: Giant Dielectric Propertiesmentioning

confidence: 95%

Microstructural Evolution and High-Performance Giant Dielectric Properties of Lu3+/Nb5+ Co-Doped TiO2 Ceramics

et al. 2021

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Giant dielectric (GD) oxides exhibiting extremely large dielectric permittivities (ε’ > 104) have been extensively studied because of their potential for use in passive electronic devices. However, the unacceptable loss tangents (tanδ) and temperature instability with respect to ε’ continue to be a significant hindrance to their development. In this study, a novel GD oxide, exhibiting an extremely large ε’ value of approximately 7.55 × 104 and an extremely low tanδ value of approximately 0.007 at 103 Hz, has been reported. These remarkable properties were attributed to the synthesis of a Lu3+/Nb5+ co-doped TiO2 (LuNTO) ceramic containing an appropriate co-dopant concentration. Furthermore, the variation in the ε’ values between the temperatures of −60 °C and 210 °C did not exceed ±15% of the reference value obtained at 25 °C. The effects of the grains, grain boundaries, and second phase particles on the dielectric properties were evaluated to determine the dielectric properties exhibited by LuNTO ceramics. A highly dense microstructure was obtained in the as-sintered ceramics. The existence of a LuNbTiO6 microwave-dielectric phase was confirmed when the co-dopant concentration was increased to 1%, thereby affecting the dielectric behavior of the LuNTO ceramics. The excellent dielectric properties exhibited by the LuNTO ceramics were attributed to their inhomogeneous microstructure. The microstructure was composed of semiconducting grains, consisting of Ti3+ ions formed by Nb5+ dopant ions, alongside ultra-high-resistance grain boundaries. The effects of the semiconducting grains, insulating grain boundaries (GBs), and secondary microwave phase particles on the dielectric relaxations are explained based on their interfacial polarizations. The results suggest that a significant enhancement of the GB properties is the key toward improvement of the GD properties, while the presence of second phase particles may not always be effective.

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Influences of Sr2+ Doping on Microstructure, Giant Dielectric Behavior, and Non-Ohmic Properties of CaCu3Ti4O12/CaTiO3 Ceramic Composites

Cited by 13 publications

References 41 publications

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

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

Significantly Improved Colossal Dielectric Properties and Maxwell—Wagner Relaxation of TiO2—Rich Na1/2Y1/2Cu3Ti4+xO12 Ceramics

Microstructural Evolution and High-Performance Giant Dielectric Properties of Lu3+/Nb5+ Co-Doped TiO2 Ceramics

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