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

Boonlakhorn, Jakkree; Prachamon, Jirata; Manyam, Jedsada; Krongsuk, Sriprajak; Thongbai, Prasit; Srepusharawoot, Pornjuk

doi:10.1039/d1ra02707g

Cited by 26 publications

(13 citation statements)

References 43 publications

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“…Hence, Na + is likely to occupy Cu 2+ sites. This observation is confirmed by earlier experimental and theoretical investigations 34,[40][41][42] . As demonstrated by Li et al 43 , Ti 4+ ions can reduce their oxidation state to Ti 3+ .…”

Section: Discussionsupporting

confidence: 88%

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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Section: Discussionsupporting

confidence: 88%

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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“…The impact of Al might be the principal source of grain size growth in the doped material. Generally, at low sintering temperatures, liquid phase sintering (LPS) processes may result in a significant grain growth rate [9,12,42]. For a CCTO system doped with Al 3+ , the CuO-Al 2 O 3 , CaO-TiO 2 , and Al 2 O 3 -TiO 2 phases form at high temperatures (about 1100 °C) [43].…”

Section: Resultsmentioning

confidence: 99%

“…In recent years, increased interest in dielectric materials, attributed to their potential technical uses in microelectronic systems [1][2][3][4][5][6][7][8][9][10][11][12][13][14], has encouraged the development of numerous compounds with very high dielectric permittivity (ε′), including co-doped TiO 2 [6], ACu 3 Ti 4 O 12 (A = Ca, Cd, Y 2/3 , Na 1/2 La 1/2 ) [1-5, 10-12, 14], co-doped SnO 2 [7], and others, contributing to recent achievements in dielectric research. Ca 0.25 Cu 0.75 TiO 3 or CaCu 3 Ti 4 O 12 (CCTO) perovskite oxide is one of the most alluring materials.…”

Section: Introductionmentioning

confidence: 99%

“…Various research groups have investigated the repercussions of metal ion doping. Improved dielectric properties, especially lowering tanδ, can be achieved in Sr 2+ [3], Lu 3+ [5], Mg 2+ [8], Al 3+ [1,12,18,19], Cd 2+ /F − [9], Bi 3+ /Al 3+ [20], and Al 3+ /F − [4] doped CCTO. When doping with various elements, the origins of a decreased tanδ might result from several distinct sources.…”

Section: Introductionmentioning

confidence: 99%

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Dielectric properties of the Ca_0.25Cu_0.75-xAl_xTiO₃ ceramics: experimental and computational investigations

Boonlakhorn,

Suksangrat,

Srepusharawoot

2024

Mater. Res. Express

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In this study, we employed a solid-state reaction method to synthesize Ca0.25Cu0.75-xAlxTiO3 ceramics, investigating the impact of Al doping at concentrations of x=0 and 0.0125. Notably, all ceramics exhibited a primary phase of Ca0.25Cu0.75TiO3. The addition of Al3+ induced a significant increase in grain size. Density functional theory analyses revealed a preferential occupation of Cu sites by Al, leading to liquid-phase sintering processes attributed to excess Cu. Moreover, it was also found from DFT that the Al dopant cannot induce an oxygen vacancy in the lattice. Charge density analysis revealed that Cu+ and Ti3+ observed via XPS originate from the presence of an oxygen vacancy. The Ca0.25Cu0.7375Al0.0125TiO3 ceramic exhibited a very high dielectric permittivity of 9.23×104 and a low dielectric loss tangent of 0.057 at 1 kHz and room temperature. Importantly, the dielectric permittivity exhibited impressive stability over a temperature range of -60 °C to 110 °C, perfectly meeting the practical requirements for utilization in X6R ceramic capacitors. Our investigation indicates that the improved dielectric properties may be attributed to enhanced grain boundary responses, influenced by oxygen enrichment and the presence of metastable insulating layers at grain boundaries. Combining experimental findings with theoretical evidence, our study elucidates that the excellent dielectric properties of the Ca0.25Cu0.7375Al0.0125TiO3 ceramic originate from an extrinsic effect arising from grain boundary enhancement. This work not only contributes to advancing the understanding of the underlying mechanisms governing dielectric behavior in doped ceramics, but also emphasizes the potential of Ca0.25Cu0.7375Al0.0125TiO3 as a promising material for applications demanding superior dielectric performance.

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“…According to Bragg's law, the shift in the Bragg angle was affected by a change in the spacing of the crystallographic planes, where the tensile strain increases the d-spacing, causing a shift in the Bragg angle of the diffraction peak towards lower 2θ values, whereas compressive strain decreases the d-spacing, resulting the shift towards higher 2θ values in the XRD pattern [39]. Average grain size, which was estimated using SEM images and ImageJ software [40], is also shown in Figure 2c.…”

Section: Resultsmentioning

confidence: 99%

Magnetron Sputter-Deposited β-Ga2O3 Films on c-Sapphire Substrate: Effect of Rapid Thermal Annealing Temperature on Crystalline Quality

Pech

Kim

2022

Coatings

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Gallium oxide (Ga2O3) is a semiconductor with a wide bandgap of ~5.0 eV and large breakdown voltages (>8 MV·cm−1). Among the crystal phases of Ga2O3, the monoclinic β-Ga2O3 is well known to be suitable for many device applications because of its chemical and thermal stability. The crystalline quality of polycrystalline β-Ga2O3 films on c-plane sapphire substrates was studied by rapid thermal annealing (RTA) following magnetron sputtering deposition at room temperature. Polycrystalline β-Ga2O3 films are relatively simple to prepare; however, their crystalline quality needs enhancement. The β-phase was achieved at 900 °C with a crystallite size and d-spacing of 26.02 and 0.2350 nm, respectively, when a mixture of ε- and β-phases was observed at temperatures up to 800 °C. The strain was released in the annealed Ga2O3 films at 900 °C; however, the clear and uniform orientation was not perfect because of the increased oxygen vacancy in the film at that temperature. The improved polycrystalline β-Ga2O3 films with dominant (−402)-oriented crystals were obtained at 900 °C for 45 min under a N2 gas atmosphere.

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

Abstract: CdF2 defect clusters result in enhancement of dielectric properties of the Ca1−xCdxCu3Ti4O12−2yF2y ceramics.

Cited by 26 publications

References 43 publications

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

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

Dielectric properties of the Ca_0.25Cu_0.75-xAl_xTiO₃ ceramics: experimental and computational investigations

Magnetron Sputter-Deposited β-Ga2O3 Films on c-Sapphire Substrate: Effect of Rapid Thermal Annealing Temperature on Crystalline Quality

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

Abstract: CdF2 defect clusters result in enhancement of dielectric properties of the Ca1−xCdxCu3Ti4O12−2yF2y ceramics.

Cited by 26 publications

References 43 publications

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

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

Dielectric properties of the Ca0.25Cu0.75-xAlxTiO3 ceramics: experimental and computational investigations

Magnetron Sputter-Deposited β-Ga2O3 Films on c-Sapphire Substrate: Effect of Rapid Thermal Annealing Temperature on Crystalline Quality

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

Dielectric properties of the Ca_0.25Cu_0.75-xAl_xTiO₃ ceramics: experimental and computational investigations