Tellurium doped n-type Zintl Zr3Ni3Sb4 thermoelectric materials: Balance between carrier-scattering mechanism and bipolar effect

Physical Insights on the Lattice Softening Driven Mid‐Temperature Range Thermoelectrics of Ti/Zr‐Inserted SnTe—An Outlook Beyond the Horizons of Conventional Phonon Scattering and Excavation of Heikes’ Equation for Estimating Carrier Properties

“…At the mid‐low temperature regime, the log[σ] for the optimized Ti/Zr doped compositions display T –0.25 dependence, suggesting the possibilities for “mixed scattering mechanisms” in this low‐temperature domain, which is known to dominate when the temperature exponent reaches close to 0. [ 73–75 ] At a higher temperature regime, a steep reduction of log[σ] is observed with a larger slope (≈ T –0.8 − T –0.97 ), which can be attributed to the additional acoustic phonon scattering, as the phonon concentration ( n ph ) generally increases with T . [ 75,76 ] Thus, the mixed scattering mechanisms can explain the rationale behind increased μ w (Figure 9) especially at the mid‐low temperature ranges).…”

“…At the mid-low temperature regime, the log[σ] for the optimized Ti/ Zr doped compositions display T -0.25 dependence, suggesting the possibilities for "mixed scattering mechanisms" in this low-temperature domain, which is known to dominate when the temperature exponent reaches close to 0. [73][74][75] At a higher temperature regime, a steep reduction of log[σ] is observed with a larger slope (≈T -0.8 − T -0.97 ), which can be attributed to the additional acoustic phonon scattering, as the phonon concentration (n ph ) generally increases with T. [75,76] Thus, the mixed scattering mechanisms can explain the rationale behind increased μ w (Figure 9) especially at the mid-low temperature ranges). In the past, such strategical tuning of carrier scattering mechanisms has been reported to improve the PF for n-type Mg 3 Sb 2 -based materials, where the mobility was enhanced by converting the ionized scattering into mixed scattering between ionization (σ ∝ T 1.5 ) and acoustic phonon scattering (σ ∝ T −1.5 ), which less effectively scatters the carriers.…”

Phase-transition temperature suppression to achieve cubic GeTe and high thermoelectric performance by Bi and Mn codoping

“…Conventional methods to enhance the ZT mainly include optimizing carrier concentration and strengthening point-defect phonon scattering (6, 7), but peak ZT was limited to around unity from the 1950s to the 1990s (8). Recently proposed effective concepts or strategies, including ''phonon glass electron crystal'' to design new compounds (6), band-structure engineering to maximize the power factor (PF = S 2 σ) (9)(10)(11)(12)(13), microstructure engineering to suppress the κ lat (14)(15)(16)(17), and point-defect engineering to optimize performance (18)(19)(20)(21), have led to the remarkable progress in the thermoelectric area (22)(23)(24)(25)(26). It should be noted that PbTe, one of the oldest and most-studied thermoelectric materials (27), plays a major role in evoking enthusiasm for current thermoelectric study since most conceptual breakthroughs have come from the recent study of the PbTe system (11,15,28,29).…”

A Review on Fundamentals, Design and Optimization to High ZT of Thermoelectric Materials for Application to Thermoelectric Technology

“…The bandgap of several semiconductor materials has been successfully tuned by doping, and increasing the bandgap has been reported to suppress the minority carriers by shifting thermal excitations of minority carriers at high temperatures. [121][122][123][124] For instance, as an example, Fig. 9a shows Te doping in Zintl compound Zr 3 Ni 3 Sb 4 121 that leads to an increase in the bandgap to 0.28 eV as compared to 0.22 eV for un-doped Zr 3 Ni 3 Sb 4 .…”

“…[121][122][123][124] For instance, as an example, Fig. 9a shows Te doping in Zintl compound Zr 3 Ni 3 Sb 4 121 that leads to an increase in the bandgap to 0.28 eV as compared to 0.22 eV for un-doped Zr 3 Ni 3 Sb 4 . This enhanced bandgap reduces the bipolar effect at high temperatures and, as a result, the Seebeck coefficient does not deteriorate at elevated temperature.…”