Mechanochemical production and investigation of nanocomposite thermoelectric ceramics based on heavy multicomponent doped β-FeSi/sub 2/

Abstract

The iron disilicide is a perspective thermoelectric material for generator, available for mass production. It has low efficiency (ZT-0.2-0.4). There are ways to level up the efficiency: particles size decreasing (to nanoscale), nonconventional alloying elements and multicomponent doping, heterophases additives inputting, 2D ( 3D) superlattice production. The aim of this work is to synthesise mechanochemically the nanocomposite on the base of doped P-FeSi2 and to investigate the influence of multycomponent doping on the thermoelectric properties. The mechanical alloying of elements was carry out in intensive planetary ball mill AGO-2, ISSC SB RAS construction, the ball acceleration was 600 mlsec*. The intensity factor was varied by the different balls diameter (3-15 mm). The samples of powders were analyzed by the X-ray diffractometry. After mechanical alloying, the samples phase content was the mixtures of FeSi, P-FeSi2 and Fe(Si). The average particle sizes were 200-1000 nm. The reaction sintering leads to the nanocomposites with 20-100 nm grains. After compacting and low temperature annealing a phases content was the thermoelectric beta-iron disilicide. The dopants status and electrical characteristics were investigated.

Environmental-friendly thermoelectric materials

“…However, compared to other non-environmental friendly materials such as Bi2Te3, PbTe and CoSb3, the thermoelectric performance of β-FeSi2 is not satisfying for practical applications [111]. Although current highest achievement of iron disilicide has only maximum efficiency of ZT = 0.4 for n-type β-FeSi2 and ZT=0.25 for p-type β-FeSi2 [115,116], it is still recognized as an important thermoelectric material due to the highly natural abundance of Fe and Si and also its environmental friendly material.…”