Anisotropy and enhancement of thermoelectric performance of Sr0.8La0.067Ti0.8Nb0.2O3−δceramics by graphene additions

Srivastava, Deepanshu; Norman, Colin; Azough, Feridoon; Ekren, Dursun; Chen, K.; Reece, Michael J.; Kinloch, Ian A.; Freer, Robert

doi:10.1039/c9ta02883h

Cited by 34 publications

(30 citation statements)

References 63 publications

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“…Generally, r = ½ for ionic solids. [ 67 ] The calculated values for carrier density, mobility, and effective mass are presented in Table 1 . It must be noted that the carrier concentration obtained from such an equation is much higher than what we usually get from Hall measurements, because the spin–orbit coupling and configurational entropy contributions are assumed to be negligible in Heikes’ formula.…”

Section: Resultsmentioning

confidence: 99%

Physical Insights on the Lattice Softening Driven Mid‐Temperature Range Thermoelectrics of Ti/Zr‐Inserted SnTe—An Outlook Beyond the Horizons of Conventional Phonon Scattering and Excavation of Heikes’ Equation for Estimating Carrier Properties

Muchtar

Srinivasan

Tonquesse

et al. 2021

Advanced Energy Materials

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Most of the best known SnTe‐based materials exhibit an attractive thermoelectric figure of merit (zT) only at the high‐temperature regime, but their performance at the low‐mid temperature ranges is quite uninspiring, and this discordance necessitates a large temperature gradient (∆T ≥ 550 K) to effectuate a reasonable efficiency, η. Here, the transition elements, Ti and Zr, that have not been used in the past are tried as dopants for SnTe and an enhanced device/average zT and/or η are reported with a lower ∆T ≈ 400 K and without the requisite for a stupendous peak/maximum zT. This notable performance emanates from—i) improved weighted mobility by optimally balancing between effective mass, carrier concentration, and mobility, ii) coupling of charge carriers with magnetic entropy, and the paramount factor being the iii) weakening of the chemical bonds (lattice softening). The thermal damping caused by lattice softening affects the phonon group velocity and the elastic properties, and the resultant increase in the degree of anharmonicity and the high density of internal strain‐fields, along with the phonon scattering effects, play an active role in tuning the overall thermoelectric performance. This work also excavates/opens up the discussion of applying the Heikes’ equation to qualitatively compare the trend of charge carriers for a given thermoelectric material system.

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Section: Resultsmentioning

confidence: 99%

Physical Insights on the Lattice Softening Driven Mid‐Temperature Range Thermoelectrics of Ti/Zr‐Inserted SnTe—An Outlook Beyond the Horizons of Conventional Phonon Scattering and Excavation of Heikes’ Equation for Estimating Carrier Properties

Muchtar

Srinivasan

Tonquesse

et al. 2021

Advanced Energy Materials

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“…Considerable work has been devoted to SiTiO 3 (STO) based thermo-generators due to its high-temperature stability, its non-toxicity, and thermal properties tailoring by multiple doping. Srivastava et al [ 115 ] studied the thermoelectric behavior of La, Nb-doped SrTiO 3 with different additions of GNP and rGO, verifying the anisotropic electrical and thermal conductivity induced by the use of the spark plasma sintering (SPS) densification method.…”

Section: Piezo and Thermoelectric Ceramic/graphene Composites For Energy Harvestingmentioning

confidence: 99%

Applications of Ceramic/Graphene Composites and Hybrids

et al. 2021

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Research activity on ceramic/graphene composites and hybrids has increased dramatically in the last decade. In this review, we provide an overview of recent contributions involving ceramics, graphene, and graphene-related materials (GRM, i.e., graphene oxide, reduced graphene oxide, and graphene nanoplatelets) with a primary focus on applications. We have adopted a broad scope of the term ceramics, therefore including some applications of GRM with certain metal oxides and cement-based matrices in the review. Applications of ceramic/graphene hybrids and composites cover many different areas, in particular, energy production and storage (batteries, supercapacitors, solar and fuel cells), energy harvesting, sensors and biosensors, electromagnetic interference shielding, biomaterials, thermal management (heat dissipation and heat conduction functions), engineering components, catalysts, etc. A section on ceramic/GRM composites processed by additive manufacturing methods is included due to their industrial potential and waste reduction capability. All these applications of ceramic/graphene composites and hybrids are listed and mentioned in the present review, ending with the authors’ outlook of those that seem most promising, based on the research efforts carried out in this field.

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“…Highly textured samples usually exhibit strong anisotropy of TE properties. Essentially, along the ab plane, electrical conductivity and thermal conductivity will be maximized while the Seebeck coefficient will be minimized [79,80], because of the reduced grain boundary barriers; in contrast, properties across the ab plane are the opposite. Therefore, different sintering techniques, including template, seed-assisted molten salt process [78], hot pressing (HP) [81,82], spark plasma sintering (SPS) [83][84][85], laser floating zone process [76], tape casting [86,87] and high-magnetic-field sintering [88], have been utilized to enhance the preferred grain orientation.…”

Section: Optimization Of Fabrication Routementioning

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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Anisotropy and enhancement of thermoelectric performance of Sr_0.8La_0.067Ti_0.8Nb_0.2O_3−δceramics by graphene additions

Abstract: Orientation of graphene platelets in SrTiO3 ceramic composites leads to significant anisotropy in electrical conductivity and thermal conductivity.

Cited by 34 publications

References 63 publications

Physical Insights on the Lattice Softening Driven Mid‐Temperature Range Thermoelectrics of Ti/Zr‐Inserted SnTe—An Outlook Beyond the Horizons of Conventional Phonon Scattering and Excavation of Heikes’ Equation for Estimating Carrier Properties

Physical Insights on the Lattice Softening Driven Mid‐Temperature Range Thermoelectrics of Ti/Zr‐Inserted SnTe—An Outlook Beyond the Horizons of Conventional Phonon Scattering and Excavation of Heikes’ Equation for Estimating Carrier Properties

Applications of Ceramic/Graphene Composites and Hybrids

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

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