Polymeric synthesis and conventional versus laser sintering of CaCu3Ti4O12 electroceramics: (micro)structures, phase development and dielectric properties

Jesus, L.M.; Santos, J.C.A.; Sampaio, D.V.; Barbosa, L. B.; Silva, Ronaldo S.; M’Peko, Jean-Claude

doi:10.1016/j.jallcom.2015.09.027

Cited by 35 publications

(17 citation statements)

References 29 publications

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“…At point (c) a single CCTO phase is finally synthesized (the Miller hkl index numbers are indicated between parentheses). While talking in this case about synthesizing CCTO at a furnace temperature of 713 ℃ for virtually zero annealing time, in zero-field approach this Pechini-derived precursor powder would have needed to be heat treated for 2 h at about 800 ℃ to get a second phase-free CCTO powder [32]. At points (d) and (e) incidence of a single CCTO phase is also verified.…”

Section: Resultsmentioning

confidence: 88%

“…Preparation of the CaCu 3 Ti 4 O 12 precursor powder was based on the Pechini chemical method [31,32]. In summary, calcium, copper, and titanium citrates were separately prepared using calcium carbonate (CaCO 3 , Synth, 99%), copper nitrate (Cu(NO 3 ) 2 •3H 2 O, Labsynth, 98%), and titanium isopropoxide (Ti[OCH(CH 3 ) 2 ] 4 , Alfa Aesar, 97%) mixed in stoichiometric amounts with citric acid (CA), previously dissolved in distilled water (0.1 g•mL -1 ), at the molar ratios of 1:3 (Ca:CA) for calcium and 1:6 (Cu, Ti:CA) for copper as well as titanium.…”

Section: Methodsmentioning

confidence: 99%

“…The precursor powder was synthesized following the identical Pechini preparation protocol, as reported in Ref. [32] and summarized above, except for the use of Bi 2 O 3 in place of CaCO 3 as starting raw material.…”

Section: Methodsmentioning

confidence: 99%

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Ultrafast synthesis and sintering of materials in a single running experiment approach by using electric fields

2019

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Processing of materials in the form of ceramics normally involves several steps including calcination at a relatively low temperature for synthesis of the end-product powder and sintering at a high temperature for densification. The work we have been developing introduces a novel approach enabling synthesis plus sintering of materials in a single running experiment by using electric fields, ending with dense ceramics that display grains noticeably finer than in conventional processing. This new paradigm is fully illustrated with experiments conducted on amorphous CaCu 3 Ti 4 O 12 precursor powder, shown to experience, on heating, crystallization through intermediate phases, followed by chemical reaction leading to synthesis of the end-product powder, plus densification depending on field adjustment. The processing time and furnace temperature are considerably reduced, demonstrating that enhanced synthesis and sintering rates applied under field input. Similar results found in Bi 2/3 Cu 3 Ti 4 O 12 are also shown. The different factors that may contribute to this unique scenario, including Joule heating, defect generation, and reduction of free energy for nuclei formation promoted by the applied field, are briefly discussed. Overall, the findings we bring here are exclusive as they show an exploitable way that allows rapid processing of materials with good control over particle and grain coarsening.

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Section: Resultsmentioning

confidence: 88%

Section: Methodsmentioning

confidence: 99%

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Ultrafast synthesis and sintering of materials in a single running experiment approach by using electric fields

2019

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“…One of the most promising materials for such applications is CCTO (CaCu 3 Ti 4 O 12 ) due to the stability of its colossal relative permittivity over a wide range of temperatures and frequencies [2,3]. Nevertheless, the dielectric loss of CCTO is considerably dependent on the preparation method [4][5][6]. The origin of the interesting dielectric properties of CCTO is controversially discussed in the literature.…”

Section: Introductionmentioning

confidence: 99%

Sintering Temperature, Frequency, and Temperature Dependent Dielectric Properties of Na0.5Sm0.5Cu3Ti4O12 Ceramics

et al. 2021

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NSCTO (Na0.5Sm0.5Cu3Ti4O12) ceramics have been prepared by reactive sintering solid-state reaction where the powder was prepared from the elemental oxides by mechanochemical milling followed by conventional sintering in the temperature range 1000–1100 °C. The influence of sintering temperature on the structural and dielectric properties was thoroughly studied. X-ray diffraction analysis (XRD) revealed the formation of the cubic NSCTO phase. By using the Williamson–Hall approach, the crystallite size and lattice strain were calculated. Scanning electron microscope (SEM) observations revealed that the grain size of NSCTO ceramics is slightly dependent on the sintering temperature where the average grain size increased from 1.91 ± 0.36 μm to 2.58 ± 0.89 μm with increasing sintering temperature from 1000 °C to 1100 °C. The ceramic sample sintered at 1025 °C showed the best compromise between colossal relative permittivity (ε′ = 1.34 × 103) and low dielectric loss (tanδ = 0.043) values at 1.1 kHz and 300 K. The calculated activation energy for relaxation and conduction of NSCTO highlighted the important role of single and double ionized oxygen vacancies in these processes.

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“…Therefore, we can consider that our sample I presents the optimal balance of both quantities-permittivity and losses. An interesting balance in dielectric properties is also found in the samples tested by Jesus et al [37] that show a relative permittivity of 21,000 and loss tangent of 0.2 at 10 kHz.…”

Section: Electrical Propertiesmentioning

confidence: 57%

Synthesis and Pressure-Assisted Sintering of CaCu3Ti4O12 Dielectrics

et al. 2021

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In this paper, we examined the dielectric properties of CaCu3Ti4O12 (CCTO) ceramics fabricated by various routes and discussed the most important conditions affecting their dielectric behavior. We prepared feedstock powder using a molten salt route and compared it with a commercial powder. Both powders were sintered using SPS. For some samples, annealing was applied after sintering. Other samples were obtained by high-pressure forming and conventional sintering, using both powders. Phase composition, porosity and microhardness were evaluated in comparison with the literature. The results showed that a sintering temperature just below or equal to 1000 °C should be set for the SPS process. However, the best dielectric characteristics were obtained in samples prepared by high-pressure forming and conventional sintering, which showed a relative permittivity of 22,000 and a loss tangent of 0.13 at 1 MHz.

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Polymeric synthesis and conventional versus laser sintering of CaCu3Ti4O12 electroceramics: (micro)structures, phase development and dielectric properties

Cited by 35 publications

References 29 publications

Ultrafast synthesis and sintering of materials in a single running experiment approach by using electric fields

Ultrafast synthesis and sintering of materials in a single running experiment approach by using electric fields

Sintering Temperature, Frequency, and Temperature Dependent Dielectric Properties of Na0.5Sm0.5Cu3Ti4O12 Ceramics

Synthesis and Pressure-Assisted Sintering of CaCu3Ti4O12 Dielectrics

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