Enhanced power factor and reduced thermal conductivity of a half-Heusler derivative Ti9Ni7Sn8: A bulk nanocomposite thermoelectric material

Misra, Debasmita; Rajput, Abhishek; Bhardwaj, A.; Chauhan, Nagendra S.; Singh, Sanjay

doi:10.1063/1.4914504

Cited by 25 publications

(15 citation statements)

References 42 publications

(60 reference statements)

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“…The TEM specimens were prepared in three steps and described elsewhere. 14,15,17 The composition and elemental analysis of the samples were performed by energy dispersive spectroscopy (EDS) attached to the FE-SEM.…”

Section: Phase and Microstructural Characterizationmentioning

confidence: 99%

“…1 In spite of substantial increase in the research output and innovative breakthroughs in this area [2][3][4][5][6][7][8][9][10][11] over the past six decades, designing thermoelectric materials with ZT approaching the above targeted value has been demonstrated to be extremely difficult mainly because of the interdependence between electronic and thermal parameters (electrical conductivity, s; Seebeck coefficient, S; and thermal conductivity, k) involved in dimensionless thermoelectric figure of merit, ZT = S 2 sT/k. In recent years, nanostructuring/nanocomposites, [12][13][14][15][16][17] band structure engineering, [18][19][20][21] and doping [22][23][24][25] strategies have been seen to decouple all these parameters to achieve an improved figure of merit (ZT) in the state-of-the-art systems.…”

Section: Introductionmentioning

confidence: 99%

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Panoscopically optimized thermoelectric performance of a half-Heusler/full-Heusler based in situ bulk composite Zr_0.7Hf_0.3Ni_1+xSn: an energy and time efficient way

Bhardwaj

Chauhan

Sancheti

et al. 2015

Phys. Chem. Chem. Phys.

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All scale hierarchical architecturing, matrix/inclusion band alignment and intra-matrix electronic structure engineering, the so called panoscopic approach for thermoelectric materials has been demonstrated to be an effective paradigm for optimizing high ZT. To achieve such hierarchically organized microstructures, composition engineering has been considered to be an efficient strategy. In this work, such a panoscopic concept has been extended to demonstrate for the first time in the case of half-Heusler based thermoelectric materials via a composition engineering route. A series of new off-stoichiometric n-type Zr0.7Hf0.3Ni1+xSn (0 ≤x≤ 0.10) HH compositions have been modified to derive HH(1 -x)/full-Heusler (FH)(x) composite with an all scale hierarchically modified microstructure with FH inclusions within the matrix to study the temperature dependent thermoelectric properties. The structural analysis employing XRD, FE-SEM and HR-TEM of these materials reveal a composite of HH and FH, with hierarchically organized microstructures. In such a submicron/nano-composite, the electronic properties are observed to be well optimized yielding a large power factor; α(2)σ (∼30.7 × 10(-4) W m(-1) K(-2) for Zr0.7Hf0.3Ni1.03Sn) and reduced thermal conductivity (∼2.4 W m(-1) K(-1) for Zr0.7Hf0.3Ni1.03Sn) yielding a high ZT∼ 0.96 at 773 K for composition Zr0.7Hf0.3Ni1.03Sn which is ∼250% larger than the normal HH Zr0.7Hf0.3NiSn (ZT∼ 0.27 at 773 K). The enhancement in ZT of these composites has been discussed in terms of primary electron filtering, electron injection and several phonon scattering mechanisms such as alloy scattering, point defect scattering, and grain boundary scattering. The Bergman and Fel model is used to calculate effective thermoelectric parameters of these composites for comparing the experimental results.

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Section: Phase and Microstructural Characterizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Panoscopically optimized thermoelectric performance of a half-Heusler/full-Heusler based in situ bulk composite Zr_0.7Hf_0.3Ni_1+xSn: an energy and time efficient way

Bhardwaj

Chauhan

Sancheti

et al. 2015

Phys. Chem. Chem. Phys.

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“…18 The absence of clear inclusions demonstrates that the degree of segregation is sensitively dependent on the sample processing, which is in keeping with the wide variety of nanostructures reported in the literature. 25 Other approaches aimed at minimising κ lat include off-stoichiometric X 9 Ni 7 Sn 8 (X = Ti, Zr) compositions that form a HH matrix and a number of segregated phases, 26,27 addition of a Ti 70.5 Fe 29.5 eutectic, 28 InSb inclusions in TiCoSb, 29,30 and phase segregation involving mixtures of HH phases. [19][20][21][22][23] Recent studies have linked the low κ to phase segregation into multiple half-Heusler phases with different ratios of X-metals.…”

Section: Introductionmentioning

confidence: 99%

Compositions and thermoelectric properties of XNiSn (X = Ti, Zr, Hf) half-Heusler alloys

et al. 2015

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Rietveld analysis of neutron powder diffraction data has been used to investigate the compositions of XNiSn (X = Ti, Zr, Hf) half-Heusler alloys prepared by solid state reactions. All samples containing Ti have 2-3% excess Ni, whereas the samples with X = Zr, Hf are almost stoichiometric.Samples with mixed X-metals are characterised by the presence of 3-4 distinct X 1-x X' x Ni 1+y Sn half-Heusler phases. Variable temperature and time dependent neutron powder diffraction for X = Ti and X = Ti 0.5 Hf 0.5 demonstrates that both the amount of excess Ni and the phase distribution are stable up to at least 600 °C. Debye temperatures of 367(2) K and 317 (2) K were obtained from the thermal displacement parameters. The samples containing Ti are characterised by a ~0.15 eV bandgap and a monotonously decreasing Seebeck coefficient. The compositions with Zr and Hf have similar bandgap values but show ambipolar transitions. Analysis of the thermoelectric transport data of degenerately doped Ti 0.5 Zr 0.5 NiSn 1-z Sb z samples using a single parabolic band model demonstrates that the transport is limited by alloy scattering and yielded an effective carrier mass of 2.5(1) m e .

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“…On the contrary, the n-type benchmark HHs, i.e., ZrNiSn-based solid solutions and related derivatives 47,48 , have their ZTs still remained around unity.…”

Section: Introductionmentioning

confidence: 98%

Thermoelectric Properties of n-type ZrNiPb-Based Half-Heuslers

et al. 2017

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Here we investigate the half-Heusler ZrNiPb as a n-type thermoelectric material. Our results show that the n-type ZrNiPb-based materials can achieve high peak power factors, ~50 μW cm-1 K-2 by optimally tuning the carrier concentration via Bi doping. By further Sn-alloying in Pb site, we achieve a significant reduction of lattice thermal conductivity while maintaining the power factor almost unchanged and hence noticeably improve the ZT. Our work demonstrates that n-type ZrNiPb-based half-Heuslers are promising thermoelectric materials.

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Enhanced power factor and reduced thermal conductivity of a half-Heusler derivative Ti9Ni7Sn8: A bulk nanocomposite thermoelectric material

Cited by 25 publications

References 42 publications

Panoscopically optimized thermoelectric performance of a half-Heusler/full-Heusler based in situ bulk composite Zr_0.7Hf_0.3Ni_1+xSn: an energy and time efficient way

Panoscopically optimized thermoelectric performance of a half-Heusler/full-Heusler based in situ bulk composite Zr_0.7Hf_0.3Ni_1+xSn: an energy and time efficient way

Compositions and thermoelectric properties of XNiSn (X = Ti, Zr, Hf) half-Heusler alloys

Thermoelectric Properties of n-type ZrNiPb-Based Half-Heuslers

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Enhanced power factor and reduced thermal conductivity of a half-Heusler derivative Ti9Ni7Sn8: A bulk nanocomposite thermoelectric material

Cited by 25 publications

References 42 publications

Panoscopically optimized thermoelectric performance of a half-Heusler/full-Heusler based in situ bulk composite Zr0.7Hf0.3Ni1+xSn: an energy and time efficient way

Panoscopically optimized thermoelectric performance of a half-Heusler/full-Heusler based in situ bulk composite Zr0.7Hf0.3Ni1+xSn: an energy and time efficient way

Compositions and thermoelectric properties of XNiSn (X = Ti, Zr, Hf) half-Heusler alloys

Thermoelectric Properties of n-type ZrNiPb-Based Half-Heuslers

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Panoscopically optimized thermoelectric performance of a half-Heusler/full-Heusler based in situ bulk composite Zr_0.7Hf_0.3Ni_1+xSn: an energy and time efficient way

Panoscopically optimized thermoelectric performance of a half-Heusler/full-Heusler based in situ bulk composite Zr_0.7Hf_0.3Ni_1+xSn: an energy and time efficient way