Dielectric response mechanism and suppressing high-frequency dielectric loss in Y2O3 grafted CaCu3Ti4O12 ceramics

Han, Fuzhu; Ren, Shaokai; Deng, Jianming; Yan, Tianxiang; Ma, Xing; Peng, Biaolin; Liu, Laijun

doi:10.1007/s10854-017-7671-2

Cited by 26 publications

(13 citation statements)

References 34 publications

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“…CaCu 3 Ti 4 O 12 (CCTO) has a cubic perovskite structure and a giant relative permittivity of 10 4 ∼ 10 6 near the room temperature. While the dielectric permittivity of CCTO exhibits a very small temperature dependence between 100 K and 600 K, it drops rapidly to a value of ∼ 100 below 100 K. [1][2][3][4][5][6][7][8][9][10] This overall behavior of CCTO is very different from either relaxors or normal ferroelectrics. It is established that the origin of such high permittivity is an extrinsic effect, which in polycrystalline CCTO is modeled with internal barrier layer capacitor (IBLC), consisting of semiconducting grains separated by thin insulating grain boundaries leading to high dielectric permittivity.…”

Section: Introductionmentioning

confidence: 99%

Localized polarons and conductive charge carriers: Understanding CaCu3Ti4O12 over a broad temperature range

et al. 2019

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CaCu 3 Ti 4 O 12 (CCTO) has a large dielectric permittivity that is independent of the 1 arXiv:1810.08949v3 [cond-mat.mtrl-sci] 17 Nov 2018 probing frequency near the room temperature, which complicated due to the existence of several dynamic processes. Here, we consider the combined effects of localized charge carriers (polarons) and thermally activated charge carriers using a recently proposed statistical model to fit and understand the permittivity of CCTO measured at different frequencies over the whole temperature range accessible by our experiments. We found that the small permittivity at the lowest temperature is related to polaron frozen, while at higher temperatures the rapid increase is associated with the thermal excitation of polarons inducing the Maxwell-Wagner effect, and the final increase of the permittivity is attributed to the thermally activated conductivity. Such analysis enables us to separate the contributions from localized polarons and conductive charge carriers and quantify their activation energies.

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Section: Introductionmentioning

confidence: 99%

Localized polarons and conductive charge carriers: Understanding CaCu3Ti4O12 over a broad temperature range

et al. 2019

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“…The dielectric constant (ε′) and dielectric loss (tan δ) measurements were recorded at room temperature for these samples as a function of frequency, and they are plotted in Figure a,b. For Li + -substituted sample, ε′ and tan δ were 9.90 and 3.70, respectively, at room temperature, and these were slightly greater than the values for nonstoichiometric spinel (ε′ = 8.80 and tan δ = 2.45). , In general, enhanced dielectric behavior was noted in the low-frequency region, and with increased frequency, dielectric constant was found to decrease, reaching saturation in the high-frequency region. Similar trends could be noted for dielectric loss as well.…”

Section: Resultsmentioning

confidence: 75%

“…But at higher frequencies, relaxation time required by the dipole to align in the direction of applied field would decrease, leading to lower dielectric constant and dielectric loss. The higher dielectric constant for the lithium-substituted sample could be due to the space charge polarization . The temperature-dependent dielectric constant and dielectric loss measurements of these samples were carried out in the temperature and frequency ranges of 100–400 K and 1–200 kHz, respectively.…”

Section: Resultsmentioning

confidence: 99%

Interplay between Defects and Cation Nonstoichiometry in Lithium-Substituted CdGa₂O₄ Leading to Multifunctional Behavior

2018

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Stoichiometric and nonstoichiometric cadmium gallate (gallium-rich) samples have been synthesized by a modified epoxide gel method. Cubic spinel arrangement was inferred for stoichiometric and gallium-rich compositions from powder X-ray diffraction analysis. Complete structural analysis employing Raman spectroscopy has been carried out to find the intricate differences between these two samples. Additional evidence for the cubic symmetry and elemental ratio of these samples has been gathered using microscopy techniques and energy-dispersive X-ray analysis. Li+ substitution for Cd2+ in gallium-rich spinel was examined, and up to 60 mol % of Cd2+ could be substituted with Li+, retaining the spinel arrangement. The introduction of lithium led to a decrease in cubic lattice parameter. Changes in the vibration modes upon lithium substitution were analyzed by Fourier transform infrared and Raman spectral measurements. The band gap value was found to increase with increase in lithium content, indicative of the Burstein–Moss effect in this system. Oxygen vacancies created as a result of lithium substitution was further examined by oxygen-ion conductivity (493–773 K) and dielectric spectroscopic measurements (100–400 K). The estimated activation energy, from these measurements, suggested major contribution of doubly ionized oxygen vacancies to the conductivity in addition to lithium-ion mobility in Li+-substituted samples. A possible defect structure operative in this system has been proposed. The catalytic role of oxygen vacancies as defect centers has been favorably utilized for the photodegradation of aqueous methylene blue dye solution.

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“…From the experimental investigations of Shannon 36 and Tkach et al 37 , the covalent radii of Y 3+ with 9 coordination numbers, Ca 2+ with 12 coordination numbers and Cu 2+ with 6 nearest neighbors are 1.23 Å, 1.48 Å and 0.87 Å, respectively. In the case of Y-doped CCTO, earlier experimental investigations 38 , 39 revealed that the lattice constant of this structure is reduced. In other words, Y ions should occupy sites with larger covalent radii.…”

Section: Discussionmentioning

confidence: 92%

Computational and experimental investigations of the giant dielectric property of Na1/2Y1/2Cu3Ti4O12 ceramics

Boonlakhorn

Suksangrat

Sarakorn

et al. 2023

Sci Rep

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A modified sol-gel method was used to successfully produce Na1/2Y1/2Cu3Ti4O12 ceramics with high dielectric permittivity. The dielectric permittivity of Na1/2Y1/2Cu3Ti4O12 ceramics reaches values larger than 104 at room temperature and 1 kHz. Moreover, these ceramics exhibit two distinct thermally induced dielectric relaxations over a broad temperature range. The loss tangent is indeed small, ~0.032–0.035. At low temperatures, dielectric relaxation was attributed to the oxygen vacancy effect, while at high temperatures, it was attributed to grain boundary and sample-electrode contact effects. Our calculations revealed that Y and Na ions are likely to occupy Ca and Cu sites, respectively. As a result, other Cu related phases, especially CuO, were observed at the grain boundaries. Based on our analysis, there is a charge compensation between Na and Y ions in Na1/2Y1/2Cu3Ti4O12. Additionally, the Cu+ and Ti3+ states observed in our XPS study originate from the presence of an oxygen vacancy in the lattice. Last, the primary cause of the enormous dielectric permittivity of Na1/2Y1/2Cu3Ti4O12 ceramics primarily comes from the internal barrier layer capacitor effect.

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Dielectric response mechanism and suppressing high-frequency dielectric loss in Y2O3 grafted CaCu3Ti4O12 ceramics

Cited by 26 publications

References 34 publications

Localized polarons and conductive charge carriers: Understanding CaCu3Ti4O12 over a broad temperature range

Localized polarons and conductive charge carriers: Understanding CaCu3Ti4O12 over a broad temperature range

Interplay between Defects and Cation Nonstoichiometry in Lithium-Substituted CdGa₂O₄ Leading to Multifunctional Behavior

Computational and experimental investigations of the giant dielectric property of Na1/2Y1/2Cu3Ti4O12 ceramics

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Dielectric response mechanism and suppressing high-frequency dielectric loss in Y2O3 grafted CaCu3Ti4O12 ceramics

Cited by 26 publications

References 34 publications

Localized polarons and conductive charge carriers: Understanding CaCu3Ti4O12 over a broad temperature range

Localized polarons and conductive charge carriers: Understanding CaCu3Ti4O12 over a broad temperature range

Interplay between Defects and Cation Nonstoichiometry in Lithium-Substituted CdGa2O4 Leading to Multifunctional Behavior

Computational and experimental investigations of the giant dielectric property of Na1/2Y1/2Cu3Ti4O12 ceramics

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Interplay between Defects and Cation Nonstoichiometry in Lithium-Substituted CdGa₂O₄ Leading to Multifunctional Behavior