RETRACTED: Introducing Ta2O5 nanoparticles into Ca3Co4O9 matrix for increased thermoelectric property through phonon scattering

Xu, Ke; Liu, Hong

doi:10.1016/j.ceramint.2020.07.057

Cited by 10 publications

(5 citation statements)

References 46 publications

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“…Relative densities were calculated based on Archimedes' principle using water as a fluid and adopting the value of 4.67 g/cm 3 as theoretical density for Ca 3 Co 4 O 9 . The crystalline phases of calcined powders and ceramics were identified through X-ray diffraction analysis (XRD -Shimadzu 6000) with Cu-Kα radiation (λ = 1.5405 Å), an integration time of 0.5 s, and a step size of 0.02 °.…”

Section: Methodsmentioning

confidence: 99%

“…The theoretical density of each sample was determined by applying the rule of mixtures, which considers the crystalline phase amount and density of each phase. For Ca 3 Co 4 O 9 13 , Ca 3 Co 2 O 6 and Co 3 O 4 phases, densities of 4.67 g/cm 3 , 4.50 g/cm 3 [ICOD #021-0138], and 6.05 g/cm 3 [ICOD #042-1467], respectively, were adopted. These values were used to calculate ρ relative .…”

Section: Methodsmentioning

confidence: 99%

“…Ca 3 Co 4 O 9 (CCO) ceramics have attracted significant research interest 3 , mainly due to their high chemical resistance and thermal stability at high temperatures 4 . Moreover, CCO ceramics are environmentally friendly, involving low temperatures for its production, and exhibit no toxicity 5 , making this cobaltite oxide a significant alternative for thermoelectric applications 6 .…”

Section: Introductionmentioning

confidence: 99%

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Thermoelectric Properties of Ca3Co4O9 Using Microwave Synthesis and Sintering

et al. 2023

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Ca 3 Co 4 O 9 powders and ceramics were synthesized and sintered using microwave-assisted heating method.Another batch of powders was calcined by the conventional heating method and this powder was used to produce ceramics sintered by microwave sintering aiming to compare with those prepared by microwave method. The formation of the phases based on calcination method and time was assessed by X-ray diffractometry. The synthesis and sintering methods affected various properties of the ceramics, including grain size, density, phase amount, Seebeck coefficient, thermal conductivity and electrical conductivity. Microwave heating method reduced the time required for the powder synthesis and sintering of ceramics. Ceramics produced using powder obtained by the conventional method presented Figure of Merit (ZT) values of approximately 0.04. However, these values were reduced for the ceramics produced by microwave heating reaching a value of about 0.02. The evaluation of the thermoelectric properties of the Ca 3 Co 4 O 9 ceramics suggests that the main issue to enhance the Figure of Merit of the CCO ceramics is related to density and Ca 3 Co 4 O 9 phase amount present in the ceramics.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermoelectric Properties of Ca3Co4O9 Using Microwave Synthesis and Sintering

et al. 2023

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“…Recently, it was shown that dispersions of nano-sized inclusions of additives, such as ln 2 O 3 , Ta 2 O 5 , and TiC [94][95][96], into the calcium cobaltite matrix is an efficient way to reduce thermal conductivity. As these nano-sized additives do not react with the matrix phase, they become embedded in the grain boundaries and interfaces, and act as scattering centers, reducing the mean free path of phonons via Rayleigh-type and geometrical phonon scattering mechanisms (figure 6) [97].…”

Section: Composite Designmentioning

confidence: 99%

“…As these nano-sized additives do not react with the matrix phase, they become embedded in the grain boundaries and interfaces, and act as scattering centers, reducing the mean free path of phonons via Rayleigh-type and geometrical phonon scattering mechanisms (figure 6) [97]. For example, calcium cobaltite ceramics containing 4.0 vol.% nanoparticles of Ta 2 O 5 (about 9.25 nm in size) or 0.25 wt.% TiC (< 200 nm in size) showed about 30% reduction in thermal conductivity at 372 K, compared to the pristine calcium cobaltite [95,96]. Conversely, Ag particles (<1000 nm in size) are frequently used to increase electrical conductivity, as the highly conductive Ag is able to create new carrier transport routes inside the composite [98,99].…”

Section: Composite Designmentioning

confidence: 99%

Calcium cobaltite, a promising oxide for energy harvesting: effective strategies toward enhanced thermoelectric performance

Freer

2022

J. Phys. Energy

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Thermoelectric (TE) materials are able to generate power from waste heat and thereby provide an alternative source of sustainable energy. Calcium cobaltite is a promising p-type thermoelectric oxide because of its intrinsically low thermal conductivity arising from the misfit layered structure. Its structural framework contains two sublayers with different incommensurate periodicities, offering different sites for substituting elements; the plate-like grain structure contributes to texture development, thereby providing opportunities to modulate the thermoelectric response. In this topical review, we briefly introduce the misfit crystal structure of calcium cobaltite and summarize three efficient strategies to enhance the thermoelectric performance, namely (i) elemental doping, (ii) optimization of fabrication route, and (iii) composite design. For each strategy, examples are presented and performance enhancing mechanisms are discussed. The roles of dopants, processing routes and phase composition are clearly identified to provide insights into processing-structure-property relationship for calcium cobaltite based materials. We outline some of the challenges that still need to be addressed and hope that the proposed strategies can be exploited in other thermoelectric systems.

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