Effect of sintering conditions on microstructure and dielectric properties of CaCu3Ti4O12 (CCTO) ceramics

Löhnert, Romy; Schmidt, Rainer; Töpfer, J.

doi:10.1007/s10832-015-9982-0

Cited by 44 publications

(14 citation statements)

References 22 publications

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“…Several approaches have been used to reduce tan δ of CCTO through the application of different processing parameters, doping different elements into CCTO or combining it with another material to produce composite . One of the most interesting approaches is by fabrication of CCTO composites via incorporation of glass as additive.…”

Section: Introductionmentioning

confidence: 99%

Effective dielectric loss (tan δ) reduction of CaCu₃Ti₄O₁₂ (CCTO) via various addition of glasses

Rahman

Ain

Mohamed

et al. 2018

Int J Applied Ceramic Tech

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Addition of various glasses has successfully reduced tan δ of CCTO-based ceramics. Less amounts (0-1.0 wt%) of glasses (BaO-SrO-Nb 2 O 5 -B 2 O 3 -SiO 2 [BSNBS] and SrO-B 2 O 3 -SiO 2 [SBS], respectively) were added into pure CCTO and sintered at 1040°C for 10 hours. The phase formation and microstructure of each sample were characterized using X-ray diffraction and scanning electron microscopy, respectively. The dielectric behavior of the samples was measured at 1 MHz. The addition of BSNBS and SBS glasses (≤0.5 wt%) successfully reduced tan δ of CCTO from 0.5 until 0.4 and 0.39, respectively, and simultaneously increased ε r .Smaller tan δ and ε r were further obtained when the added glasses were more than 0.5 wt%. These behaviors were due to segregation of glasses together with precipitation of CuO which decreased the grain size, and caused the presence of pores at grain boundaries. Therefore, small amount of various additions of glasses could modify the CCTO dielectric properties.

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Section: Introductionmentioning

confidence: 99%

Effective dielectric loss (tan δ) reduction of CaCu₃Ti₄O₁₂ (CCTO) via various addition of glasses

Rahman

Ain

Mohamed

et al. 2018

Int J Applied Ceramic Tech

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“…In particular, the relative dielectric permittivity of Ag-migrated CCTO sintered for 2 h was almost 52 times that of the as-sintered CCTO ceramic; this Ag-migrated CCTO specimen has the highest value among the specimens. The metastable phase behavior was reported depending on sintering temperature and dwell time 29 . The relative dielectric permittivity of CCTO ceramic sintered at 1050 °C was higher than that of the CCTO ceramic sintered at 1100 °C.…”

Section: Resultsmentioning

confidence: 99%

Ag-migration effects on the metastable phase in CaCu3Ti4O12 capacitors

Lee

Shin

et al. 2018

Sci Rep

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The silver migration effect into the metastable phase forms a micro-electric path, to enhance the relative dielectric permittivity of CaCu3Ti4O12 ceramics for electronic devices. Controlling the sintering time uniquely develops the metastable phase of as-sintered CaCu3Ti4O12 ceramics. A post-heating process that applies the migration of silver into the metastable phase increases the relative dielectric permittivity. At 1 kHz frequency, the relative dielectric permittivity at room temperature of the silver-migrated CaCu3Ti4O12 ceramics sintered for 2 h is 565.9 × 103, almost 52 times higher than that of the as-sintered CaCu3Ti4O12 ceramics. The selected area electron diffraction (SAED) patterns of the large and small grains were similar, but differed from those of the metastable region, including the grain boundary of the as-sintered CaCu3Ti4O12 ceramics sintered for 2 h by TEM technique. This phenomenon suggests that enabling Ag-migration into the metastable phase develops a micro-electric path that improves the relative dielectric permittivity of CaCu3Ti4O12 ceramics.

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“…There are appearances of three types of morphologies, which can be categorized as; type A: bimodal distribution of grains, type B: small and homogeneous grain sizes, type C: large and uniform grain distributions. CCTO films, sputtered at lower RF power, has shown bimodal grain distributions and this trend observed up to RF power of 75 W. This may be due to the formation of segregated CuO at the grain boundaries and leads to the nonuniform grain growth [24][25][26]. During annealing of CCTO films (grown at lower RF power) copper was diffused out of the grain boundary and the film surface became rough due to copper-oxide segregation.…”

Section: Methodsmentioning

confidence: 99%

Effect of RF sputtering power on morphological and electrical properties of calcium copper titanate thin films

Tripathy

Das

Ghosh

et al. 2017

J Mater Sci: Mater Electron

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dielectric constant, but these are limited to low temperature applications. Beyond the Curie temperature (T c ) their dielectric properties decreases dramatically, which is undesirable for device applications. Recently, CaCu 3 Ti 4 O 12 (CCTO), possessing a distorted cubic perovskite structure, has received intensive consideration due to its extraordinary dielectric behavior [7]. The dielectric constant of CCTO ceramics is in the order of 10 5 over a broad range of temperature due to its stable cubic structure [8] and also no lattice distortion has been observed in CCTO between this temperature range as confirmed by neutron diffraction and high resolution X-ray diffraction [7,8]. The origin of high permittivity in CCTO is still under debate. High dielectric behavior is the common feature in ferroelectric materials. In case of CCTO, the contribution from dipoles has been ruled out due to its centrosymmetry nature even at low temperature [7,8]. The internal barrier layer mechanism is widely accepted for explanation of giant dielectric permittivity in CCTO, where the conducting grains are separated by insulating grain boundaries [9]. Application of CCTO in microelectronics for memory devices, sensors, capacitor and varistors demands the deposition of CCTO thin films on silicon substrate.Due to the unique dielectric behavior of CCTO bulk ceramics, many research groups have initiated deposition of CCTO thin films by different deposition techniques [10-16] on various types of substrates [17][18][19]. Sputtering is considered as one of the most promising deposition technique for thin film deposition [20]. There are very few reports of deposition of CCTO thin film by RF sputtering [12,21]. Sputtering parameters like RF power, deposition pressure, substrate temperature strongly influence the structural, morphological and electrical properties of thin films. In our previous work [22], we have deposited CCTO thin film with the variation of deposition pressure on silicon Abstract Calcium copper titanate (CCTO) thin films were deposited on p-type silicon substrate by RF magnetron sputtering at various RF powers. Post deposition annealing was carried out for all the samples at 950 °C for 1 h in air atmosphere. Various types of surface morphology have been observed for CCTO thin films with the variation of RF power. The evolution of polycrystalline structure of the CCTO thin films was confirmed by XRD studies. The FTIR characteristic absorption band of CCTO was observed in the range of 400-700 cm −1 . The capacitancevoltage (C-V) and current-voltage (I-V) characteristics of the films were investigated employing Al/CCTO/Si MOS capacitors. CCTO films with higher dielectric constant, lower oxide and interface charge density were obtained at higher RF power. Leakage current was also found to be minimum for RF power of 105 W.

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Effect of sintering conditions on microstructure and dielectric properties of CaCu3Ti4O12 (CCTO) ceramics

Cited by 44 publications

References 22 publications

Effective dielectric loss (tan δ) reduction of CaCu₃Ti₄O₁₂ (CCTO) via various addition of glasses

Effective dielectric loss (tan δ) reduction of CaCu₃Ti₄O₁₂ (CCTO) via various addition of glasses

Ag-migration effects on the metastable phase in CaCu3Ti4O12 capacitors

Effect of RF sputtering power on morphological and electrical properties of calcium copper titanate thin films

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Effect of sintering conditions on microstructure and dielectric properties of CaCu3Ti4O12 (CCTO) ceramics

Cited by 44 publications

References 22 publications

Effective dielectric loss (tan δ) reduction of CaCu3Ti4O12 (CCTO) via various addition of glasses

Effective dielectric loss (tan δ) reduction of CaCu3Ti4O12 (CCTO) via various addition of glasses

Ag-migration effects on the metastable phase in CaCu3Ti4O12 capacitors

Effect of RF sputtering power on morphological and electrical properties of calcium copper titanate thin films

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Effective dielectric loss (tan δ) reduction of CaCu₃Ti₄O₁₂ (CCTO) via various addition of glasses

Effective dielectric loss (tan δ) reduction of CaCu₃Ti₄O₁₂ (CCTO) via various addition of glasses