The effect of Ni doping on the thermoelectric transport properties of CdO ceramics

Gao, Linjie; Wang, Shufang; Liu, Ran; Zhai, Shengli; Zhang, Hongrui; Wang, Jianglong; Fu, Guangsheng

doi:10.1016/j.jallcom.2015.12.043

Cited by 31 publications

(15 citation statements)

References 31 publications

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“…Moreover, no XRD peaks for 80% Ni and 100% Ni samples were detected, indicating that polycrystalline films got amorphized at that higher level of Ni doping and thus limit to calculate the average particle diameter of them. Unlike L. Gao et al works where 3% and 5% Ni doped CdO ceramic exhibit a secondary NiO phase, [34] here, no signature of secondary NiO phase was observed in GAXRD pattern even after 40% Ni doping, suggesting that doping in ceramic bulk samples using conventional solid state reaction method is completely different approach then thin films prepared by solgel technique.…”

Section: Compositional and Structural Studiescontrasting

confidence: 93%

Orbital hybridization-induced band offset phenomena in Ni_xCd_1−xO thin films

et al. 2020

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We present the cationic impurity assisted band offset phenomena in NixCd1-xO (x= 0, 0.02, 0.05, 0.1, 0.2, 0.4, 0.8, 1) thin films and further discussed in the light of orbital hybridization modification. Compositional and structural studies revealed that cationic substitution of Cd 2+ by Ni 2+ ions leads to a monotonic shift in (220) diffraction peak, indicating the suppression of lattice distortion while evolution of local strain with increasing Ni concentration mainly associated to the mismatch in electro-negativity of Cd 2+ and Ni 2+ ion. In fact, Fermi level pinning towards conduction band minima takes place with increasing Ni concentration at the cost of electronically compensated oxygen vacancies, resulting modification in the distribution of carrier concentration which eventually affects the band edge effective mass of conduction band electrons and further endorses band gap renormalization. Besides that, the appearance of longitudinal optical (LO) mode at 477 cm -1 as manifested by Raman spectroscopy also indicate the active involvement of electron-phonon scattering whereas modification in local coordination environment particularly anti-crossing interaction in conjunction with presence of satellite features and shake-up states with Ni doping is confirmed by X-ray absorption near-edge and X-ray photoelectron spectroscopy studies. These results manifest the gradual reduction of orbital hybridization with Ni incorporation, leading to decrement in the band edge effective mass of electron. Finally, molecular dynamics simulation reflects 13% reduction in lattice parameter for NiO thin film as compared to undoped one while projected density of states calculation further supports the experimental observation of reduced orbital hybridization with increasing Ni concentration.Inter university accelerator centre) between the localized d states rather than between band like states like usual semiconductors [20]. So the term "optical gap" instead of "band gap" will be better to be casted off.In the present report, we have synthesized the NixCd1-xO (NDO) thin films for the whole composition range and a detailed study has been carried out on their structural, optical and chemical properties. In particular, we demonstrate the doping induced local strain, electron-electron, electron-ionized impurity interaction and strong electron phonon coupling leads to renormalization of band gap in NDO thin films.The dramatic dependence of the optical gap, moreover, with composition also has a strong correlation with phonon scattering such as optical phonon deformation potential, charged impurity scattering and also phonon stiffening as evidenced by Raman spectroscopy. Moreover, we consider the p-d hybridization between O p and Ni/Cd d orbitals in order to determine the CBM and VBM energy levels, suggesting that p-d hybridization becomes less effective with increasing Ni doping and subsequently affects band gap renormalization by reducing the effective mass of electron at conduction band edge. Complementary Xray absorption near-edge sp...

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Section: Compositional and Structural Studiescontrasting

confidence: 93%

Orbital hybridization-induced band offset phenomena in Ni_xCd_1−xO thin films

et al. 2020

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“…The values determined at room temperature (0.42 mW/K 2 m) are higher than the measured in pure and doped sintered materials (between 0.3 and 0.4 mW/K 2 m) [17][18][19]27,32], with the only exception of the Ni-doped CdO (0.5 mW/K 2 m) [22].…”

Section: Results and Discusionmentioning

confidence: 62%

“…CdO can be described using a rock-salt structure with Fm3 m space group [20] and possess a sublimation point of 1559 ºC [21]. This last parameter can drastically influence the processing conditions, even if relatively high density materials can be produced when sintered at relatively low temperatures [22]. As a consequence, some processes producing very high density and highly conductive ceramics via melt-solidification [23,24] are unuseful due to the absence of a liquid phase.…”

Section: Introductionmentioning

confidence: 99%

High mechanical and thermoelectric performances in hot-pressed CdO

Madre

Torres

Sotelo

2016

J Mater Sci: Mater Electron

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High density bulk CdO polycrystalline thermoelectric ceramics have been prepared through a hot-pressing process. Density measurements have revealed that density reaches 99.5 % of the theoretical one, in agreement with the observed microstructure. Microhardness has shown to have indentation size effect, decreasing when the load is raised. Electrical resistivity shows metalliclike behaviour until 650 ºC and semiconducting-like at higher temperatures while Seebeck coefficient increases in the metallic-like region and decreases in the semiconducting one. The maximum power factor values, 1.6 mW/K 2 m, have been achieved at about 650 ºC. These values are the highest obtained in this family of materials, with the advantage of its low thermal treatment duration, when compared with the typical solid state sintering process.

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“…zT of 0.41 at 973 K was reported in La-doped SrTiO 3 by Lu et al [183]. A record high zT>0.6 at 1000-1100 K was observed in La-Nb-doped SrTiO 3 nanopowders [33]. Such high zT is due to the increase in carrier concentration and electrical conductivity by La and Nb doping.…”

Section: Oxide Thermoelectricmentioning

confidence: 84%

“…Such high zT is due to the increase in carrier concentration and electrical conductivity by La and Nb doping. The thermal conductivity, on the other hand, is reduced through complex microstructures [33]. Gd/W double substitution in polycrystalline calcium magnetite Ca 0.99 Gd 0.01 Mn 0.99 W 0.01 O 3 resulted in the zT of 0.12 at 700°C [185].…”

Section: Oxide Thermoelectricmentioning

confidence: 99%

Odyssey of thermoelectric materials: foundation of the complex structure

et al. 2018

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Growing energy crises and pollution are the major issues of the modern world. The thermoelectric concept seems to be the promising solution to deal with these problems, because of the ability of thermoelectric materials to convert waste heat into electricity without adding more pollution to the atmosphere. The development of thermoelectric materials (TE) is driven by fundamental interest and their potential applications. To replace the conventional techniques, the figure of merit (zT) of the thermoelectric materials should be higher than 2 for power generation and greater than 3 for cooling. Recently, there have been significant advances in enhancing the figure of merit of thermoelectric materials and also to find new materials for the thermoelectric purpose. Low thermal conductivity is the key for a promising thermoelectric material that can be achieved through the complex structures. This review provides insights into the recent advancements in improving the efficiency of thermoelectric systems, complex nature of thermoelectric materials, with a concise introduction to preparative approaches for thermoelectric (TE) materials.

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The effect of Ni doping on the thermoelectric transport properties of CdO ceramics

Cited by 31 publications

References 31 publications

Orbital hybridization-induced band offset phenomena in Ni_xCd_1−xO thin films

Orbital hybridization-induced band offset phenomena in Ni_xCd_1−xO thin films

High mechanical and thermoelectric performances in hot-pressed CdO

Odyssey of thermoelectric materials: foundation of the complex structure

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The effect of Ni doping on the thermoelectric transport properties of CdO ceramics

Cited by 31 publications

References 31 publications

Orbital hybridization-induced band offset phenomena in NixCd1−xO thin films

Orbital hybridization-induced band offset phenomena in NixCd1−xO thin films

High mechanical and thermoelectric performances in hot-pressed CdO

Odyssey of thermoelectric materials: foundation of the complex structure

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Product

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Orbital hybridization-induced band offset phenomena in Ni_xCd_1−xO thin films

Orbital hybridization-induced band offset phenomena in Ni_xCd_1−xO thin films