Dependences of phase stability and thermoelectric properties of type-I clathrate Ba8Cu4.5Si6Ge35.5 on synthesis process parameters

Thermoelectric Properties and Stability of Nanocomposites Type I Clathrate Ba‐Cu‐Si with SiC

“…This could be the reason that the samples S0n-3 rd (n = 1-4) have higher ARTICLE ε than S0n-hp. [27] Overall, the observation follows the results from our previous investigation, [27] showing a small S c and a large ε in the ball milled powder S0n-p as well as an increased S c and decreased ε in S0n-hp. The crystallite size increases further in S0n-3 rd , indicating the instability during thermal cycling.…”

“…For composition homogeneity, each alloy was melted 4 to 5 times and the as cast alloys were annealed at 800°C for 10 d prior to water quenching (to freeze the phase constitution and composition as those at 800°C). The annealed samples were then ball milled with optimized process parameters [27,28] in a Fritsch planetary mill (Pulverisette 4) including 2 wt.-% stearic acid (CH 3 (CH2) 16 CO 2 H) as process control agent (PCA) and different amounts of (0, 1, 2, 3 wt.-%) SiC (purity Ն 99.0 %, particle size Յ 60 μm) to form a nanocomposite. The powders after ball milling were hot pressed in an FCT hot press system with pressure p = 56 MPa, temperature T = 800°C and duration h = 2 hours in Ar.…”

“…[13,[18][19][20][21][22]24,25] Still, λ ph can be further decreased by nanostructuring. [22,26,27] Although forming superlattices and quantum dots is very effective in improving ZT, [28] it is difficult to scale them up to a large volume. Bulk nanostructured materials in large quantities can be produced easily and have been widely accepted in TE material research.…”

Nanostructured clathrates and clathrate‐based nanocomposites

“…Our previous investigation on BaCuSiGe showed that the best thermoelectric performance was found in compounds with low x (). Thus, we chose the composition BaCuSiGe for further investigations ().…”

“…Hotpressed samples using powder from batch II behave quite differently in terms of stability and thermoelectric properties (). Firstly, the phase composition is not stable during the hot pressing process, as evidenced by the change of the lattice parameter of the clathrate phase and the increase of the peak intensity of the diamond phase with (Fig.…”