Optimization and Analysis of Thermoelectric Properties of Unfilled Co_1–x–yNi_xFe_ySb₃ Synthesized via a Rapid Hydrothermal Procedure

Abstract

A series of nanostructured co-doped Co(1-x-y)Ni(x)Fe(y)Sb3 were fabricated using a rapid hydrothermal method at 170 °C for a duration of 12 h, followed by evacuated-and-encapsulated heating at 580 °C for a short period of 5 h. The resulting samples were characterized using powder X-ray diffraction, field emission scanning electron microscopy, bulk density, electronic and thermal transport measurements. The power factor of Co(1-x-y)Ni(x)Fe(y)Sb3 is significantly enhanced in the high-temperature region due to significant enhancement of the electrical conductivity and absolute value of thermopower. The latter arises from the onset of bipolar effect being shifted to higher temperatures as compared with the non-doped CoSb3. The room temperature thermal conductivity falls in the range between 1.22 and 1.67 W m(-1) K(-1) for Co(1-x-y)Ni(x)Fe(y)Sb3. The thermal conductivity of both the (x,y) = (0.14,10) and (0.14,12) samples is measured up to 600 K and found to decrease with increasing temperature. The thermal conductivity of the (0.14,10) sample goes down to ∼1.02 W m(-1) K(-1). As a result, zT = 0.68 is attained at 600 K. The lattice thermal conductivity is analyzed to gain insight into the contribution of various scattering processes that suppress the heat transfer through the phonons in Co(1-x-y)Ni(x)Fe(y)Sb3. The effect of the simultaneous presence of Co, Ni, and Fe elements on the electronic structure and transport properties of Co(1-x-y)Ni(x)Fe(y)Sb3 is described using the quantum mechanical tunneling theory of electron transmission among the potential barriers.

Enhanced thermoelectric properties of hydrothermally synthesized Bi0.88−xZnxSb0.12 nanoalloys below the semiconductor–semimetal transition temperature

“…The magnitude of k L decreases upon Zn doping for both set of alloys and dominates at low temperatures but becomes smaller than electronic contribution as the temperature approaches 300 K. Point defects can account for the reduction of k L upon Zn doping due to the mass difference between Zn and Bi. 33,46,47 Moreover, the smallest k L occurs at the Zn doping content of x ¼ 0.05 and x ¼ 0.10 sintered at 170 C and 250 C, respectively. As the temperature increases up to 300 K, unlike the x ¼ 0.05 and 0.10 alloys, the k L of the x ¼ 0.15 alloy gradually approach that of the x ¼ 0.00 alloy.…”

Thermoelectric properties of Ni0.15Co3.85Sb12 and Fe0.2Ni0.15Co3.65Sb12 skutterudites prepared by HPHT method

“…4a 12 at the whole measured temperature range, which is possibly attributed to the increased carrier concentration after Fe substituting for Co [18]. The relationship between the electrical resistivity and temperature is presented in Fig.…”

Influence of multi-walled carbon nanotubes on the thermoelectric properties of La-filled CoSb3 skutterudite composites

“…However, why does the thermal conductivity change slightly when the MWCNTs doping amount is less than 2% while showing an obvious rise when the additive amount is more than 4%? First, MWCNTs distributed in the skutterudite CoSb 3…”

“…Because cobalt skutterudite compounds exhibit phonon-glass and electron-crystal (PGEC) features, these compounds have been extensively studied as promising thermoelectric materials [1][2][3]. Skutterudite compounds are regarded as some of the most promising thermoelectric materials in the high temperature range because of their potentially high figures of merit, which is represented by MX 3 (M = Co, Rh, Ir; X= P, As, Sb) with a cubic structure and the space group Im 3 .…”