Transport and thermoelectric properties of Nb-doped FeV0.64Hf0.16Ti0.2Sb half-Heusler alloys synthesized by two ball milling regimes

•P-type FeV0.64−xNbxHf0.16Ti0.2Sb alloys are prepared by arc melting followed by induction melting.•The samples were milled in two milling regimes and then sintered with spark plasma.•Thermoelectric properties were studied as functions of temperature from 300 K to 800 K.•The weighted mobility, µw, a...

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Bibliographic Details
Published in:Journal of alloys and compounds 2022-01, Vol.890, p.161838, Article 161838
Main Authors: El-Khouly, A., Adam, A.M., Altowairqi, Y., Serhiienko, I., Chernyshova, E., Ivanova, A., Kurichenko, V.L., Sedegov, A., Karpenkov, D., Novitskii, A., Voronin, A., Parkhomenko, Yu, Khovaylo, V.
Format: Article
Language:English
Subjects:
Ball milling
Doping
Electric arc melting
Electrical resistivity
Figure of merit
Half-Heusler alloys
Heat conductivity
Heat transfer
Heusler alloys
Maximum power
Mechanical alloying
Nanocomposite
Niobium
Plasma sintering
Power factor
Reduction
Room temperature
Sintering (powder metallurgy)
Spark plasma sintering
Thermal conductivity
Thermoelectric materials
Thermoelectricity
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Summary:•P-type FeV0.64−xNbxHf0.16Ti0.2Sb alloys are prepared by arc melting followed by induction melting.•The samples were milled in two milling regimes and then sintered with spark plasma.•Thermoelectric properties were studied as functions of temperature from 300 K to 800 K.•The weighted mobility, µw, and electronic quality factor, BE, were calculated.•The maximum zT value at 725 K was achieved for BM-ed FeV0.60Nb0.4Hf0.16Ti0.2Sb sample. This work presents experimental investigations of the thermoelectric properties of p-type FeV0.64−xNbxHf0.16Ti0.2Sb half-Heusler alloys. Samples of the concerned system were prepared through sequent procedures starting with arc melting. Fine powders of the concerned samples were then obtained by mechanical alloying using two different ball milling regimes. Spark plasma sintering technique was employed for pressing the powders. The thermoelectric properties were studied as functions of temperature from 300 K to 800 K. Alloy scattering of phonons showed great contribution in the reduction of lattice thermal conductivity. High energy ball milled FeV0.39Nb0.25Hf0.16Ti0.2Sb sample possessed the lowest lattice thermal conductivity with a value of 1.81 Wm−1 K−1 at room temperature with a reduction of –82% compared with that of FeVSb. Additionally, the electrical conductivity was improved by the Nb doping leading to notable increase in the material’s power factor. As a result, a maximum power factor of 19.5 μW cm−1 K−2 was achieved at 800 K for Nb doped at x = 0.4 of the ball milled samples. The figure of merit was increased from 0.25 for FeV0.64Hf0.16Ti0.2Sb to 0.44 for FeV0.60Nb0.4Hf0.16Ti0.2Sb due to Nb doping. Which means that the figure of merit value is enhanced by –43%. The value was recorded at 725 K.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2021.161838