Stability and Thermoelectric Properties of Zn₄Sb₃ with TiO₂ Nanoparticle Inclusions

Abstract

β-Zn 4 Sb 3 is a cheap nontoxic high-performance thermoelectric material, which unfortunately suffers from stability issues because of zinc migration in thermal and electrical gradients.Here, the thermoelectric properties and thermal stability of β-Zn 4 Sb 3 mixed with varying sizes and weight percentages of TiO 2 nanoparticles are investigated. Furthermore, the stability of pressed β-Zn 4 Sb 3 -TiO 2 nanocomposite pellets is investigated by measuring high-energy synchrotron powder X-ray diffraction (PXRD) data during operating conditions using the Aarhus thermoelectric operando setup (ATOS). Through these studies, it is determined that TiO 2 nanoparticle addition in pressed pellets of β-Zn 4 Sb 3 does not prevent Zn migration, and even though effects are seen in the thermal conductivity and electrical resistivity, the overall zT remains unchanged regardless of TiO 2 nanoinclusions. For the present samples, the Seebeck coefficients are unaffected by the addition of nanoparticles, and thus, there is no observed energy-filtering effect. The operando PXRD data reveal that the TiO 2 nanoinclusions lower the degradation rate by up to 75%, but all samples eventually decompose. This is corroborated by long-term stability tests performed using a thermal gradient. In conclusion, TiO 2 nanoinclusions do not degrade the excellent thermoelectric properties of β-Zn 4 Sb 3 , but the stabilizing effect is not sufficient for establishing long-term operating stability.

Aliovalent Dilute Doping and Nano‐Moiré Fringe Advance the Structural Stability and Thermoelectric Performance in β‐Zn4Sb3

“…There has been a long‐lasting debate regarding the intrinsic transport properties, homogeneity region, and high‐temperature stability of single‐phase β ‐Zn 4 Sb 3 . [ 24 , 25 ] We settled this dispute by starting with the analyses of four binary alloys, the Zn 55 Sb 45 , Zn 57 Sb 43 , Zn 58 Sb 42 , and Zn 59 Sb 41, which grew by the Bridgman method. As suggested by microstructures, X‐ray diffraction (XRD) patterns (Figure S1 , Supporting Information), and wavelength dispersive X‐ray spectroscopy (WDS) analysis (Table S1 , Supporting Information), the Zn 57 Sb 43 reveals the single‐phase feature of β ‐Zn 4 Sb 3 .…”

Insights into the Classification of Nanoinclusions of Composites for Thermoelectric Applications

“…Rigid, thermally, and electrically impermeable inclusions such as oxide nanoinclusions have a maximum effect on the thermal and electrical carriers and enhance the mechanical stability . There are various oxide-based nanoinclusions such as TiO 2 , ,− WO 3 , ,, ZrO 2 , ,,,,,,, Al 2 O 3 , ,− CeO 2 , , Y 2 O 3 , , SiO 2 , ,, ZnO, ,,,, SrTiO 3 , SnO 2 , Yb 2 O 3 , NiO, and reduced graphene oxide to improve the thermoelectric performance of the composites. Here, α is expressed as ∝ = γ – ln­( n ), where γ is the scattering factor and n is the carrier concentration; after the addition of oxide nanoinclusions, γ enhances and n decreases to increase the α in two ways.…”

Characterizing thermoelectric stability

“…70 Common for these discoveries is that they are paramount in enabling a tailored stabilization strategy to be formulated such as segmentation, 69,71 coating, 72 and elemental doping. 70,73,74 This emphasizes the importance of not only testing the stability but also understanding the mechanisms at play. A new trend in thermoelectric stability studies is to combine several characterization techniques in studying the material, while exposing it to more realistic conditions.…”