Simultaneous increase in thermopower and electrical conductivity through Ta-doping and nanostructuring in half-Heusler TiNiSn alloys

Karati, Anirudha; Mukherjee, Shriparna; Mallik, Ramesh Chandra; Shabadi, Rajashekhara; Murty, B.S.; Varadaraju, U.V.

doi:10.1016/j.mtla.2019.100410

Cited by 17 publications

(33 citation statements)

References 44 publications

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“…Thermoelectric (TE) devices are useful for solid-state energy conversion technology and offer a direct conversion of heat to electricity. These devices have great potential to generate useful energy by recycling waste heat. , Many alloy systems like half-Heuslers, − skutterudites, − silicides, , tellurides, − selenides, clathrates, and Zintl phases are being widely explored as potential materials for TE devices. The dimensionless figure of merit, ZT = S 2 T /ρκ total , is a unique parameter that measures the performance of a TE material, where S , ρ, and κ total are the Seebeck coefficient, electrical resistivity, and thermal conductivity, respectively, at absolute temperature T .…”

Section: Introductionmentioning

confidence: 99%

Effect of Refractory Tantalum Metal Filling on the Microstructure and Thermoelectric Properties of Co₄Sb₁₂ Skutterudites

et al. 2021

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We report a systematic investigation of the microstructure and thermoelectric properties of refractory element-filled nanostructured Co 4 Sb 12 skutterudites. The refractory tantalum (Ta) metal-filled Co 4 Sb 12 samples (Ta x Co 4 Sb 12 (x = 0, 0.4, 0.6, and 0.8)) are synthesized using a solid-state synthesis route. All the samples are composed of a single skutterudite phase. Meanwhile, nanometer-sized equiaxed grains are present in the Ta 0.2 Co 4 Sb 12 and Ta 0.4 Co 4 Sb 12 samples, and bimodal distributions of equiaxed grains and elongated grains are observed in Ta 0.6 Co 4 Sb 12 and Ta 0.8 Co 4 Sb 12 samples. The dominant carrier type changes from electrons (n-type) to holes (p-type) with an increase in Ta concentration in the samples. The power factor of the Ta 0.6 Co 4 Sb 12sample is increased to 2.12 mW/mK 2 at 623 K due to the 10-fold reduction in electrical resistivity. The lowest lattice thermal conductivity observed for Ta 0.6 Co 4 Sb 12 indicates the rattling action of Ta atoms and grain boundary scattering. Rietveld refinement of XRD data and the analysis of lattice thermal conductivity data using the Debye model confirm that Ta occupies at the voids as well as the Co site. The figure of merit (ZT) of ∼0.4 is obtained in the Ta 0.6 Co 4 Sb 12 sample, which is comparable to single metalfilled p-type skutterudites reported to date. The thermoelectric properties of the refractory Ta metal-filled skutterudites might be useful to achieve both n-type and p-type thermoelectric legs using a single filler atom and could be one of replacements of the rare earth-filled skutterudites with improved thermoelectric properties.

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Section: Introductionmentioning

confidence: 99%

Effect of Refractory Tantalum Metal Filling on the Microstructure and Thermoelectric Properties of Co₄Sb₁₂ Skutterudites

et al. 2021

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“…In the higher Zr content sample, on the other hand, the thermal and lattice thermal conductivity decreased to 4.6 and 1.9 W/ (m•K), respectively (Figure 11b). Among the MNiSn alloys, the κ l value of 1.9 W/(m•K) at 823 K is lower than that of Tadoped TiNiSn, 9 Zr and Nb-doped TiNiSn, 24 and Zr-doped TiNiSn 8 as well as Hf-doped ZrNiSn. 13 Although the melt spun and sintered Hf-and Ti-doped ZrNiSn exhibited an ultralow κ l value of 1.0 W/(m•K), 21 close to Debye−Cahill limit in HH alloys, the associated electron scattering at the fine interfaces lowered the power factor.…”

Section: Analysis Of Transport Properties Employing First Principlesmentioning

confidence: 84%

“…Apart from their high-power factor due to their narrow band gap, HH alloys are also mechanically and thermally stable, cheap, and do not require toxic precursors . They are synthesized by induction melting (IM), levitation melting (LM), solid-state synthesis (SSS), vacuum arc melting (VAM), or mechanical alloying (MA), , followed by consolidation through hot pressing (HP) or spark plasma sintering (SPS) . Long annealing times are often needed to obtain a single majority phase, which often proves detrimental to TE properties owing to coarsening and structural disorder, apart from the loss of elements …”

Section: Introductionmentioning

confidence: 99%

“…Heavier isovalent Zr and n-type Ta, along with p-type light-element Al, were selected to investigate the effect of mass-induced phonon scattering and the effect of the doping-induced strain. Considering the high solubility of Zr in Ti and the low solubility of Ta in Ti, the phase separation of Ti and Zr-rich HH phases and Ta-rich precipitates can influence the TE properties.…”

Section: Introductionmentioning

confidence: 99%

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Low-Lattice Thermal Conductivity in Zr-Doped Ti₂NiCoSnSb Thermoelectric Double Half-Heusler Alloys

Mishra

Tan

Trivedi

et al. 2023

ACS Appl. Energy Mater.

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The effect of doping on the thermoelectric properties of Half-Heusler (HH) high-entropy alloy (HEA) Ti2NiCoSnSb was studied. Lower thermal conductivity was observed with increased Sb doping. Mass scattering by heavy (Ta, Zr) and light (Al) dopants was studied to further lower the thermal conductivity. Dopants at the level of up to 50% at the Ti site were studied. A high HH phase content was obtained in the Zr-doped samples, and a low-lattice thermal conductivity of 1.9 W/(m·K) was observed. This value is one of the lowest reported lattice thermal conductivities in HH alloys. The poor solubility of Ta led to undissolved Ta in the samples, which enhanced the electrical properties. In the case of Al doping, the NiAl phase raised the power factor value of Ti1.8Al0.2NiCoSn0.5Sb1.5 to 2.2 × 10–3 W/(m·K2), which is almost twice the corresponding value reported for Ti2NiCoSnSb. Interestingly, a maximum ZT of 0.29 was found in all of the doped systems, although the transport mechanism and microstructure varied widely with the type of dopant. An optimum dopant level of 25% of Zr, 7.5% of Ta, and 10% of Al is necessary to obtain the maximum ZT in these alloys. Compared to HH systems, the HH high-entropy alloy (HEA) systems provide a larger composition field for tuning the transport properties by simultaneous doping of multiple elements to lower the thermal conductivity.

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“…Many researches on the thermoelectric properties of HH compounds show moderately high ZT of ≈1.0 in the mid to high temperature ranges (700-1000 K) [1] which makes them as potential candidates for high efficiency power generation. Recently, several experimental [2][3][4] and theoretical [5][6][7] studies have been focused on the doped HH alloys, these last can be utilized in a broad temperature region and a good part of their raw materials are nontoxic, abundant and cheap [8][9][10][11]. The single doping remains one of the effective process, which adjust the electrical power factor and reduce the thermal conductivity [12].…”

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confidence: 99%

Investigation on Electronic and Thermoelectric Properties of (P, As, Sb) Doped ZrCoBi

Djelti

Anissa

Bestani

2021

EEJP

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Since the last decade, the half-Heusler (HH) compounds have taken an important place in the field of the condensed matter physics research. The multiplicity of substitutions of transition elements at the crystallographic sites X, Y and (III-V) elements at the Z sites, gives to the HH alloys a multitudes of remarkable properties. In the present study, we examined the structural, electronic and thermoelectric properties of ZrCoBi0.75Z0.25 (Z = P, As, Sb) using density functional theory (DFT). The computations have been done parallel to the full potential linearized augmented plane wave (FP-LAPW) method as implemented in the WIEN2k code. The thermoelectrically properties were predicted via the semi-classical Boltzmann transport theory, as performed in Boltztrap code. The obtained results for the band structure and densities of states confirm the semiconductor (SC) nature of the three compounds with an indirect band gap, which is around 1eV. The main thermoelectric parameters such as Seebeck coefficient, thermal conductivity, electrical conductivity and figure of merit were estimated for temperatures ranging from zero to 1200K. The positive values of Seebeck coefficient (S) confirm that the ZrCoBi0.75Z0.25 (x = 0 and 0.25) are a p-type SC. At the ambient temperature, ZrCoBi0.75P0.25 exhibit the large S value of 289 µV/K, which constitutes an improvement of 22% than the undoped ZrCoBi, and show also a reduction of 54% in thermal conductivity (κ/τ). The undoped ZrCoBi has the lowest ZT value at all temperatures and by substituting bismuth atom by one of the sp elements (P, As, Sb), a simultaneous improvement in κ/τ and S have led to maximum figure of merit (ZT) values of about 0.84 obtained at 1200 K for the three-doped compounds.

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Simultaneous increase in thermopower and electrical conductivity through Ta-doping and nanostructuring in half-Heusler TiNiSn alloys

Cited by 17 publications

References 44 publications

Effect of Refractory Tantalum Metal Filling on the Microstructure and Thermoelectric Properties of Co₄Sb₁₂ Skutterudites

Effect of Refractory Tantalum Metal Filling on the Microstructure and Thermoelectric Properties of Co₄Sb₁₂ Skutterudites

Low-Lattice Thermal Conductivity in Zr-Doped Ti₂NiCoSnSb Thermoelectric Double Half-Heusler Alloys

Investigation on Electronic and Thermoelectric Properties of (P, As, Sb) Doped ZrCoBi

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Simultaneous increase in thermopower and electrical conductivity through Ta-doping and nanostructuring in half-Heusler TiNiSn alloys

Cited by 17 publications

References 44 publications

Effect of Refractory Tantalum Metal Filling on the Microstructure and Thermoelectric Properties of Co4Sb12 Skutterudites

Effect of Refractory Tantalum Metal Filling on the Microstructure and Thermoelectric Properties of Co4Sb12 Skutterudites

Low-Lattice Thermal Conductivity in Zr-Doped Ti2NiCoSnSb Thermoelectric Double Half-Heusler Alloys

Investigation on Electronic and Thermoelectric Properties of (P, As, Sb) Doped ZrCoBi

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Effect of Refractory Tantalum Metal Filling on the Microstructure and Thermoelectric Properties of Co₄Sb₁₂ Skutterudites

Effect of Refractory Tantalum Metal Filling on the Microstructure and Thermoelectric Properties of Co₄Sb₁₂ Skutterudites

Low-Lattice Thermal Conductivity in Zr-Doped Ti₂NiCoSnSb Thermoelectric Double Half-Heusler Alloys