Enhanced thermoelectric properties of Ca3Co4O9+δ by Ni, Ce co-doping

Tang, Guodong; Yang, Wenchao; He, Yun; Wang, Z.H.

doi:10.1016/j.ceramint.2015.02.021

Cited by 14 publications

(5 citation statements)

References 30 publications

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“…The electrical conductivity of the intrinsic Cu 2 SnSe 3 compound is extremely low (1.1 × 10 4 S m –1 ) leading to a relatively low power factor and thus a poor thermoelectric performance. Adjusting the relative stoichiometric ratio and doping with alien valent elements are the common methods for optimizing the carrier concentrations to improve its electronic transport properties. ,,− For example, Liu et al investigated the effect of phase segregation on the thermoelectric properties of Cu 2 SnSe 3 compounds by adjusting the contents of Cu and Sn. It was found that a small quantity of the CuSe or SnSe 2 secondary phase improves their thermoelectric properties .…”

Section: Introductionmentioning

confidence: 99%

Role of Cation Vacancies in Cu₂SnSe₃ Thermoelectrics

Cheng

You

et al. 2019

ACS Appl. Mater. Interfaces

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In this study, a series of Cu2–x SnSe3 (x = 0.075–0.175) and Cu2Sn1–y Se3 (y = 0.06–0.1) compounds were synthesized by self-propagating high-temperature synthesis combined with plasma-activated sintering. The effects of different cation vacancies (Cu vacancies and Sn vacancies) on the thermoelectric properties are systematically studied. Both Cu vacancies and Sn vacancies enhance the carrier densities and move the Fermi level deeply into the valence band, promoting the multiband from Γ and S points involved in the electrical transport and increasing the effective mass, which is further corroborated by the theoretical calculation. Due to the stronger carrier scattering caused by Cu vacancies, the mobilities of samples with Cu deficiencies reduce leading to decreased power factors. The power factors of samples with Sn deficiencies increase owing to the increased carrier concentration and attaining a maximum power factor of 10.17 μW cm–1 K–2 at 800 K. Besides, the deficiencies of both Cu and Sn strengthen the phonon scattering, and samples with Cu deficiencies obtain lower thermal conductivity than samples with Sn deficiencies due to the lower electronic thermal conductivity. All the samples with cation deficiencies have improved thermoelectric properties. For Cu1.875SnSe3, ZT reaches 0.95 at 800 K, which is 83% higher than those of undoped samples, while for Cu2Sn0.93Se3, ZT reaches 0.87 at 800 K, which is a 67% improvement.

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Section: Introductionmentioning

confidence: 99%

Role of Cation Vacancies in Cu₂SnSe₃ Thermoelectrics

Cheng

You

et al. 2019

ACS Appl. Mater. Interfaces

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“…In the sol-gel preparation method, ethylene glycol, polyethylene glycol, and nitric acid were used to polymerize the solution, induce nitrate salt decomposition, and facilitate new compound formation [32,33]. On the other hand, citric acid and polyethylene glycol were used to polymerize the solution which produces carbonaceous xerogel and needs to be crushed [3,31,[34][35][36]. Some researchers focused on the preparation of Ca 3 Co 4 O 9 powder with different calcination conditions by using different preparation techniques.…”

mentioning

confidence: 99%

Effects of calcination temperature and time on the Ca3Co4O9 purity when synthesized using starch-assisted sol-gel combustion method

2020

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Ca 3 Co 4 O 9 is a p-type semiconducting material that is well-known for its thermoelectric (TE), magnetic, electronic, and electro-optic properties. In this study, sol-gel autoignition was used to prepare Ca 3 Co 4 O 9 at different calcination temperatures (773, 873, 973, and 1073 K) and time (4, 6, 8, 10, 12, and 14 h) using starch as a fuel. The phase and microstructure of the prepared Ca 3 Co 4 O 9 powder were investigated. Thermogravimetry-differential thermal analysis (TGA) confirms that the final weight loss occurred at 1073 K to form Ca 3 Co 4 O 9 stable powder. The variable-pressure scanning electron microscopy (VP-SEM) images show that the size of powder particles increases from 1.15 to 1.47 μm as calcination time increases from 4 to 12 h, and the size remains almost constant thereafter. A similar pattern is also observed on the increment of the crystallite size and percentage of crystallinity with X-ray diffraction (XRD) analysis. The highest crystallinity is found about 92.9% when the powder was calcinated at 1073 K for 12 and 14 h with 458 and 460 Å crystallite size, respectively. Energy dispersive X-ray spectroscopy (EDS) analysis demonstrates that the calcinated powder has a high intensity of Ca, Co, and O with uniform distribution. High-resolution transmission electron microscopy (HRTEM) images prove that there is no distinct lattice distortion defect on the crystal structure.

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“…In literature, Ni-Ce co-doped CCO was investigated by Tang et al They reported that Ni doping at Co site of Ce-doped CCO cause increase in resistivity due to increase in carrier scattering. Besides, they stated that Ni doping increases the thermopower value due to the spin entropy [38]. The CCO was also co-doped with Ni-Lu and it was mentioned that rare-earth heavy metal (Lu) doping on Ca site causes phonon scattering and Ni doping at Co site leads to spin entropy enhancement [37].…”

Section: Te Characterizationmentioning

confidence: 99%

“…The electrons and the holes contribute to both electrical conductivity and electronic thermal conductivity, therefore, κ e component of thermal conductivity follows the Wiedemann-Franz law, and every action taken to increase electrical conductivity increases κ e which in turn increases the total thermal conductivity. However, the phonons contribute to only lattice thermal conductivity and therefore, it is more efficient to control the κ L component to decrease the overall thermal conductivity and hence to maximize ZT value [22,38]. κ L can be reduced by adding phonon scattering centers within the crystal structure such as grain boundaries, point defects, voids, crystal defects, etc [7,24].…”

Section: Te Characterizationmentioning

confidence: 99%

“…Although most of the studies have focused on single site substitution on Ca-site or Co-site, there are limited studies on the effects of co-doping on TE properties of CCO ceramics. For instance, CCO was co-doped with Lu-Ni (ZT: 0.0185 at 350 K) [37], Ni-Ce (ZT: 0.022 at 350 K) [38], Fe-Eu (ZT: 0.027) [39], Bi-Fe (ZT: 0.4 at 973 K) [20], Y-Fe (18% higher ZT value than that of undoped sample) [23], Ag-Fe (ZT: 0.027 at 300 K) [12].…”

Section: Introductionmentioning

confidence: 99%

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Enhancement of high temperature thermoelectric performance of cobaltite based materials for automotive exhaust thermoelectric generators

BAYATA¹

2021

Smart Mater. Struct.

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Thermoelectric (TE) generators can directly convert exhaust waste heat into electricity in vehicles. However, the low conversion efficiency of TE generators is the main obstacle to their commercialization in automotive. Their efficiency mainly depends on the performance of the used materials which is quantified by the figure of merit (ZT value). In the present study, single- and co-doped calcium cobaltites(CCO) with rare-earth (Tb) and transition metals (Cu, Fe, Ni, Mn, Cr) were produced using sol-gel technique in order to improve their high temperature thermoelectric properties for heat recovery in exhaust manifold applications. By the combined effect of doping approach and the production technique used in this study, a remarkable decrease in the grain size of CCO was obtained, and thus its thermal conductivity dramatically decreased. Besides, thermopower values were improved significantly. The reduction in thermal conductivity and the increase in thermopower led to an enhancement in ZT value of CCO ceramics. Among all the co-doped samples, Tb-Cu co-doped CCO displayed the maximum ZT value of 0.116 at 873 K which is 2.5 times larger than that of pure CCO. The high thermal stability and the enhanced thermoelectric performance make Tb-Cu co-doped CCO material a potential candidate for heat recovery in automotive exhaust thermoelectric generators.

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Enhanced thermoelectric properties of Ca3Co4O9+δ by Ni, Ce co-doping

Cited by 14 publications

References 30 publications

Role of Cation Vacancies in Cu₂SnSe₃ Thermoelectrics

Role of Cation Vacancies in Cu₂SnSe₃ Thermoelectrics

Effects of calcination temperature and time on the Ca3Co4O9 purity when synthesized using starch-assisted sol-gel combustion method

Enhancement of high temperature thermoelectric performance of cobaltite based materials for automotive exhaust thermoelectric generators

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Enhanced thermoelectric properties of Ca3Co4O9+δ by Ni, Ce co-doping

Cited by 14 publications

References 30 publications

Role of Cation Vacancies in Cu2SnSe3 Thermoelectrics

Role of Cation Vacancies in Cu2SnSe3 Thermoelectrics

Effects of calcination temperature and time on the Ca3Co4O9 purity when synthesized using starch-assisted sol-gel combustion method

Enhancement of high temperature thermoelectric performance of cobaltite based materials for automotive exhaust thermoelectric generators

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Role of Cation Vacancies in Cu₂SnSe₃ Thermoelectrics

Role of Cation Vacancies in Cu₂SnSe₃ Thermoelectrics