Ball milling as an effective route for the preparation of doped bornite: synthesis, stability and thermoelectric properties

Abstract

Ball milling has been exploited for the preparation of Cu5Fe1−xMnxS4. These materials, which are p-type semiconductors, exhibit a figure of merit greater than 0.5 at moderate temperatures.

High Thermoelectric Performance of Bornite through Control of the Cu(II) Content and Vacancy Concentration

“…6). All samples in this series exhibit an increase in thermoelectric performance when compared to the parent bornite phase, 23,29 with considerable enhancements in the figure of merit: 0.61 < (ZT) max < 0.65 ( Fig. 6), being achieved for compositions with 0.06 ≤ x ≤ 0.12.…”

“…Moreover this performance is achieved at the remarkably low temperature of 550 K, suggesting that these materials are attractive candidates for energy recovery from low-grade waste-heat. The upper temperature for electrical and thermal transport property measurements was limited to 600 K owing to concerns over sample stability, including the reported appearance of a chalcopyrite-type phase above 550 K. 34 However, in previous 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 studies 23,29,34,35 of bornite-related phases, figures of merit at higher temperatures have been reported (Table 2) and the maximum value is generally achieved at ca. 700 K. Therefore the collection of thermal and electrical transport property data was extended to 700 K for a bornite-type phase close to the optimal composition, Cu 4.97 Fe 0.93 S 4 , identified here (Supplementary Information).…”

“…The upper limit for the collection of physical property data was selected following the observation by Guelou et al that stoichiometric bornite (Cu 5 FeS 4 ) begins to lose sulphur above 600 K under a flowing nitrogen atmosphere. 29 The electrical resistivity, (ρ), and Seebeck coefficient, (S), were measured simultaneously under a slight over pressure of He using a Linseis LSR-3 instrument. A gradient of 50 K was maintained across the sample for the measurement of the Seebeck coefficient.…”

“…A large number of the non-stoichiometric materials reported here exhibit values in the range 0.59 < ZT < 0.80 at 550K, representing an increase of up to 44%, with respect to previous reports. Although prior to this work, the impact of transition-metal substitution on the TE properties of bornites has been little explored, 29 it has been shown recently that the partial substitution of sulphur by selenium has a significant effect on the transport properties. 34 This suggests that anion substitution, combined with the use of cation substitution coupled with the creation of vacancies described here, may prove to be a highly-effective approach to achieving further enhancements in TE performance.…”

Twin Engineering in Solution‐Synthesized Nonstoichiometric Cu5FeS4 Icosahedral Nanoparticles for Enhanced Thermoelectric Performance

“…The variation in thermal conductivity (κ) with temperature for 10min‐773K and 30min‐773K is very similar, maintaining very low values within the whole temperature range. κ for 30min‐773K (10min‐773K) decreases from ≈0.43 (≈0.42) W m −1 K −1 at 300 K to ≈0.31 (≈0.31) W m −1 K −1 at 475 (525) K, before rising to ≈0.45 (≈0.46) W m −1 K −1 at 710 K. These κ values are relatively low compared to other examples of Cu 5 FeS 4 bulk counterparts fabricated through high‐temperature synthesis and ball milling . By contrast, κ for 60min‐773K reveals much higher values, decreasing from ≈0.52 W m −1 K −1 at room temperature to ≈0.48 W m −1 K −1 at 375–475 K before rising to ≈0.68 W m −1 K −1 at 710 K.…”