Abstract
Polycrystalline bulks of Hf-doped Cu0.01Bi2Te2.7Se0.3 are prepared via a conventional melt-solidification process and subsequent spark plasma sintering technology, and their thermoelectric performances are evaluated. To elucidate the effect of Hf-doping on the thermoelectric properties of n-type Cu0.01Bi2Te2.7Se0.3, electronic and thermal transport parameters are estimated from the measured data. An enlarged density-of-states effective mass (from ~0.92 m0 to ~1.24 m0) is obtained due to the band modification, and the power factor is improved by Hf-doping benefitting from the increase in carrier concentration while retaining carrier mobility. Additionally, lattice thermal conductivity is reduced due to the intensified point defect phonon scattering that originated from the mass difference between Bi and Hf. Resultantly, a peak thermoelectric figure of merit zT of 0.83 is obtained at 320 K for Cu0.01Bi1.925Hf0.075Te2.7Se0.3, which is a ~12% enhancement compared to that of the pristine Cu0.01Bi2Te2.7Se0.3.
Highlights
Thermoelectric (TE) technology is widely used for cooling and energy harvesting applications, since it can directly convert thermal energy into electricity by using semiconductingTE materials
Because of the anisotropic crystal structure of the Bi2 Te3 -based alloys, their electronic and thermal transport properties are strongly influenced by the measurement directions (00l orientation characteristics)
We demonstrate the important role of Hf‐doping at the Bi‐site to enhance the increases with temperature
Summary
One of the most critical factors to determine the efficiency of TE systems is the performance of the TE materials, which can be denoted by a dimensionless figure of merit, zT ( = S2 σT/κ, where S is the Seebeck coefficient, σ is the electrical conductivity, and κ is the thermal conductivity at a given absolute temperature T) Another issue in Bi2 Te3 -based TE materials is their low mechanical reliability when fabricated as ingots by using a directional solidification method, such as zone melting; this because the 00l planes held together by weak van der Waals interactions are highly aligned along the growth direction [2].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
