Thermal Stability of Barium and Indium Double-Filled Skutterudite Ba0.3In0.2Co3.95Ni0.05Sb12 Coated by SiO2 Nanoparticles

Abstract

Filled skutterudite thermoelectric (TE) materials have been extensively studied to search for better TE materials in the past decade. However, there is no detailed investigation about the thermal stability of filled skutterudite TE materials. The evolution of microstructure and TE properties of nanostructured skutterudite materials fabricated with Ba 0.3 In 0.2 Co 3.95 Ni 0.05 Sb 12 /SiO 2 core-shell composite particles with 3 nm thickness shell was investigated during periodic thermal cycling from room temperature to 723 K in this work. Scanning electronic microscopy and electron probe microscopy analysis were used to investigate the microstructure and chemical composition of the nanostructured skutterudite materials. TE properties of the nanostructured skutterudite materials were measured after every 200 cycles of quenching in the temperature range from 300 K to 800 K. The results show that the microstructure and composition of Ba 0.3 In 0.2 Co 3.95 Ni 0.05 Sb 12 /SiO 2 nanostructured skutterudite materials were more stable than those of single-phase Ba 0.3 In 0.2 Co 3.95 Ni 0.05 Sb 12 bulk materials. The evolution of TE properties indicates that the electrical and thermal conductivity decrease along with an increase in the Seebeck coefficient with increasing quenching up to 2000 cycles. As a result, the dimensionless TE figure of merit (ZT) of the nanostructured skutterudite materials remains almost constant. It can be concluded that these nanostructured skutterudite materials have good thermal stability and are suitable for use in solar power generation systems.

Synthesis, characterization and physical properties of the skutterudites YbxFe2Ni2Sb12 (0≤x≤0.4)

“…650 K. The instability of the skutterudites with respect to oxidation at elevated temperatures, presents a barrier to their implementation in practical devices. This suggests that in a device, such materials would require protection against oxidation, through the deposition of protective barrier layers [31,32].…”

In-doped multifilled n-type skutterudites with ZT= 1.8

“…A series of In-filled skutterudites of various groups prepared with various methods followed and confirmed that indium was useful as a filler. These investigations were extended to double-filled skutterudites of In with Sn [29], with Ba [3,16,[30][31][32][33][34][35][36][37], with Tl [38], with Pb [35], with Ce [6,[39][40][41][42], with Pr [27], with Nd [21,43], with Yb [7,8,16,19,[44][45][46][47][48][49], with Lu [50], and to triple filled skutterudites of In with Ba and Ce [51], with Ba and Yb [16,52], with La and Yb [47], with Ce and Yb [41,42,53] and Ga and Tl [26]. There are also attempts to improve the TE properties by doping and/or alloying e.g.…”

“…There are also attempts to improve the TE properties by doping and/or alloying e.g. substituting Co by Fe [33,[54][55][56][57][58], by Ni [31,59,60] and by Rh [61][62][63] or doping of the Sb site by Ge [20,64], by Se [65] and by Te [66][67][68][69]. Also double filled (Ba, In), substituted (Fe, Co) and doped (Sb by Ge) were investigated [36].…”

Transport Properties and Microstructure of Indium and Cerium added Cobalt-Antimony based Skutterudites

“…However the In 0.05 Ce 0.05 Co 4 Sb 12 qu sample shows a different diffractogram and already exhibits impurity phases at this lower amount of filling elements. It can be assumed that quenching cause a separation of InSb and Sb from a presumably pure phase skutterudite material, like in the case for barium and indium filled skutterudites [12]. This phenomenon does not occur for slowly cooled skutterudite material with the same composition.…”