Abstract
NiSb nanoparticles by 0.034, 0.074 and 0.16 volume fractions were successfully coated on bulk polycrystalline Ni0.05Mo3Sb5.4Te1.6 thermoelectric (TE) particles through a solvothermal route without deteriorating the bulk Ni0.05Mo3Sb5.4Te1.6 material. The samples were consolidated through hot pressing and their thermoelectric (TE) properties were characterized. At 400 K, 500 K, and 600 K, 0.074 NiSb sample exhibited 22%, 16% and 11.3% increases in the power factor (P.F.) compared to bulk material. The main contributing factor to this enhanced power factor is the elevated electrical conductivity. For the same sample, the reciprocal relationship between Seebeck coefficient and electrical conductivity is decoupled. Sample 0.16 NiSb exhibited the highest electrical conductivity among the three samples. The thermal conductivity of the 0.16 sample was less temperature sensitive compared to other samples. HRTEM and SEM tools were applied to comprehend microstructural features and their relationship to TE transport properties. Pore effect on the thermal and electrical conductivity was elucidated. This study shows that grain-boundary manipulation via this wet chemistry technique is indeed an economically viable method to fabricate and optimize the transport properties of bulk TE materials.
Highlights
Rapid progress in nanotechnology tools has given new dimensions to energy harnessing materials
The product needs to be thermodynamically and chemically stable. In this investigation NiSb nanoparticles were coated on bulk antimonide-telluride (Ni0.05Mo3Sb5.4Te1.6) particles using a simple nanocoating process similar to nanocoating CoSb3 on bulk CoSb3 and CoSb3 on bulk La0.9CoFe3Sb12.26,27 Ni0.05Mo3Sb5.4Te1.6 has a thermal conductivity of 4.0 W m–1 K–1 and a ZT of 0.96 at 1000 K.28
At 325 K, bulk and 0.034 NiSb have a κl of 3.3 W m–1K–1 and 3.0 W m–1K–1 respectively, indicating that NiSb nanoparticles are less effective in preventing phonon contribution to total thermal conductivity
Summary
Rapid progress in nanotechnology tools has given new dimensions to energy harnessing materials. Material is getting more attention.[5,6,7,8,9] The lattice component of thermal conductivity, κl, is defined by the Boltzmann equation under relaxation time approximation and is given by, κl = (1/3)Cvlv, where v is the phonon group velocity, Cv is the specific heat, and l is the phonon free path Among these parameters controlling l is the most fruitful option as many investigations show.[2,10] Reducing the mean free path results in reduction of κ, which in turn elevates the figure-of-merit, provided the electrical conductivity and the Seebeck coefficient are unaffected. The product needs to be thermodynamically and chemically stable In this investigation NiSb nanoparticles were coated on bulk antimonide-telluride (Ni0.05Mo3Sb5.4Te1.6) particles using a simple nanocoating process similar to nanocoating CoSb3 on bulk CoSb3 and CoSb3 on bulk La0.9CoFe3Sb12.26,27 Ni0.05Mo3Sb5.4Te1.6 has a thermal conductivity of 4.0 W m–1 K–1 and a ZT of 0.96 at 1000 K.28. Bulk NiSb particles (100 μm - 500 μm) have been synthesized and their TE transport properties have been characterized to ascertain their effect on Ni0.05Mo3Sb5.4Te1.6
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