Homogeneity domain and thermoelectric properties of CrSi2

Improvement of Thermoelectric Properties via Texturation Using a Magnetic Slip Casting Process–The Illustrative Case of CrSi2

“…Thanks to the larger PF and despite a higher thermal conductivity, ZT c is much higher than ZT ⊥c on the whole temperature range reaching a maximum of 0.20 at 773 K. This represents a 50 % improvement of ZT compared to the randomly oriented sample. A prove of the high quality of the texturation is that the present estimated ZT c is very similar to the ZT along the c-axis reported for single crystals (Figure 10) 34 . This demonstrates that slip casting under a magnetic field is promising as a texturation processing route to fully take advantage of thermoelectric materials with anisotropically decoupled electrical transport properties.…”

“…At 323 K for instance, κ c is higher than κ ⊥c with values of 13.5 and 10.9 W m −1 K −1 , respectively. It corresponds to a κ c /κ ⊥c ratio of 1.25 that remains constant up to the highest measured temperature of 773 K. This ratio is lower than for single crystals with reported value of 1.5 34 . This must be due the lower The electronic contribution to the thermal conductivity was estimated using the Wiedemann-Franz law to be around 0.60±0.15 W m −1 K −1 for all the samples.…”

“…Accepted manuscript / Final version (> 96 %) compared to samples from the literature which usually show relative densities in the range of 90 -92 %. In the present case, higher densities could be achieved by increasing significantly the sintering temperature to 1573 K using a pyrometer for temperature control instead of a conventional K-type thermocouple limited to a maximum temperature of 1273 K. Note that it has been shown both experimentally 78,79 and theoretically 80 that κ for CrSi 2 is relatively high mainly owing to the high lattice thermal conductivity part, which is responsible for over 90 % of κ. than [10 10] but with a significantly larger anisotropy with a ρ [0001] /ρ [10 10] ratio of 0.5 at 650 K 34,81 . Note that a quantitative comparison of electronic resistivities between polycrystalline samples and single crystals is in turn difficult to establish due to the presence of grain boundaries in the former.…”

“…(tetragonal) and CrSi 2 (hexagonal) single crystals show PF that are about 40 % higher along the aand c-axes, respectively, mostly due to higher Seebeck coefficients 34,35 . Inducing large texturation in polycrystalline materials should result in macroscopic properties comparable to single crystals without the inherent high processing cost of the latter which strongly reduces potential industrial applications.…”

“…Most thermoelectric TMSs are known to exhibit intrinsically large anisotropy of their TE properties . For example, MnSi 1.74 (tetragonal) and CrSi 2 (hexagonal) single crystals show PF values that are about 40% higher along the a - and c -axes, respectively, mostly due to higher Seebeck coefficients. , Inducing large texturation in polycrystalline materials should result in macroscopic properties comparable to single crystals without the inherent high processing cost of the latter, which strongly reduces potential industrial applications. Texturation processes reported for TMS mostly consist of sintering pellet or ribbon shaped particles under uniaxial pressure, the particle morphology being produced by cleaving large crystals along preferential crystallographic planes , or by the melt-spinning process .…”