BaBi₂O₆: A Promising n-Type Thermoelectric Oxide with the PbSb₂O₆Crystal Structure

Abstract

Thermoelectric materials offer the possibility of enhanced energy efficiency due to waste heat scavenging. Based on their high-temperature stability and ease of synthesis, efficient oxide-based thermoelectrics remain a tantalizing research goal; however, their current performance is significantly lower than the industry standards such as Bi2Te3 and PbTe. Among the oxide thermoelectrics studied thus far, the development of n-type thermoelectric oxides has fallen behind that of p-type oxides, primarily due to limitations on the overall dimensionless figure of merit, or ZT, by large lattice thermal conductivities. In this article, we propose a simple strategy based on chemical intuition to discover enhanced n-type oxide thermoelectrics. Using state-of-the-art calculations, we demonstrate that the PbSb2O6-structured BaBi2O6 represents a novel structural motif for thermoelectric materials, with a predicted ZT of 0.17–0.19. We then suggest two methods to enhance the ZT up to 0.22, on par with the current best earth-abundant n-type thermoelectric at around 600 K, SrTiO3, which has been much more heavily researched. Our analysis of the factors that govern the electronic and phononic scattering in this system provides a blueprint for optimizing ZT beyond the perfect crystal approximation.

Weak-Bonding Elements Lead to High Thermoelectric Performance in BaSnS3 and SrSnS3: A First-Principles Study

“…The absolute valence band maximum (VBM) and conduction band minimum (CBM) energies used in the fitting are corrected by deep core level according to the theory proposed by Wei et al The accuracy of the scattering rates generated by AMSET has been tested in many other IV–VI group compounds including SnO 2 , SnS, SnSe, PbS, and PbTe by yielding consistent results with the state-of-the-art EPW code . Furthermore, there have been a variety of studies implemented with the AMSET code calculating the electrical properties of compounds, such as RECuZnP 2 , Cu 7 PS 6 , Cs 3 Cu 2 I 5 , RFeO 3 , and BaBi 2 O 6 , which proves its robustness for a vast selection of materials. Finally, the scattering rates, combined with energy eigenvalues extracted from an interpolated dense k -grid of 37 × 77 × 21, are used as inputs for BoltzTraP2 to yield the electrical conductivity σ, Seebeck coefficient S , and carrier thermal conductivity κ e through the Onsager reciprocal relation …”

Y2Ti2O5S2 – a promising n-type oxysulphide for thermoelectric applications

“…35 Historically, the constant relaxation-time approximation (CRTA) has been used to solve the transport equations, but it has been shown that the mean absolute percentage error in the charge carrier mobility obtained with a constant relaxation time is unacceptable. 35,36 AM-SET improves on the CRTA by using the momentum relaxationtime approximation (MRTA) to explicitly calculate scattering rates for each electronic state within the Born approximation for a sequence of temperature and charge-carrier concentration couples. In particular, scattering due to the acoustic deformation potential (ADP), ionised impurities (IMP), piezoelectric interactions (PIE) and polar optical phonons (POP) can be evaluated, together with the effect of limiting the phonon mean-free paths by nanostructuring.…”

“…Nonetheless, it can be seen that the 300 K lattice thermal conductivity of Y 2 Ti 2 S 5 O 2 , particularly the out-of-plane component, is competitive with or lower than that of other high-performance n-type thermoelectrics such as SrTiO 3 (11 W m −1 K −1 ), PbTe (4 W m −1 K −1 ) and BaBi 2 O 6 (3.6 W m −1 K −1 ). 36,53,54…”

Y2Ti2O5S2 – a promising n-type oxysulphide for thermoelectric applications

“…33 Historically, the constant relaxation-time approximation (CRTA) has been used to solve the transport equations, but it has been shown that the mean absolute percentage error in the charge carrier mobility obtained with a constant relaxation time is unacceptable. 33,34 AMSET improves on the CRTA by using the momentum relaxation-time approximation (MRTA) to explicitly calculate scattering rates for each electronic state within the Born approximation for a sequence of temperature and charge-carrier concentration couples. In particular, scattering due to the acoustic deformation potential (ADP), ionised impurities (IMP), piezoelectric interactions (PIE) and polar optical phonons (POP) can be evaluated, together with the effect of limiting the phonon mean-free paths by nanostructuring.…”

“…Nonetheless, it can be seen that the 300 K lattice thermal conductivity of Y 2 Ti 2 S 5 O 2 , particularly the out-of-plane component, is competitive with or lower than that of other high-performance n-type thermoelectrics such as SrTiO 3 (11 W m −1 K −1 ), PbTe (4 W m −1 K −1 ) and BaBi 2 O 6 (3.6 W m −1 K −1 ). 34,50,51…”