Introducing Rare Earth Dopants for Controlled Conductivity in Thermoelectric Cobaltites

Abstract

The conversion of waste heat into electrical energy plays a key role in our current challenge to develop alternative energy technologies to reduce our dependence on fossil fuels. Thermoelectric (TE) materials are the first choice to handle this subject. In TE materials, cobaltites are the material of interest, due to their nontoxic properties. Cobaltites exhibits large TE power, low resistivity, and relatively small thermal conductivity at room temperature. TE material (BiCa 2−x R x CoO y ) where R is for rare earth like Nd, (x = 0.0, 0.2) was synthesized in nanoregime by simplified sol-gel method. Simplified sol-gel method was chosen because it gives maximum phase purity and tunable parameters for desired properties. The mechanism used to enhance thermoelectric properties is to reduce thermal conductivity of the material and increase electrical conductivity of the material using nanostructures. Material characterizations were done for structural studies using X-ray diffraction (XRD). XRD revealed monoclinic crystal structure. Temperature-dependent electrical conductivity showed an increase with increase in temperature. Thermal conductivity was also measured. Both electrical resistivity and thermal conductivity decrease as a result of neodymium doping which enhanced its importance as thermoelectric material. The different parameters were correlated to understand the conduction mechanism.

Facile synthesis and conduction mechanism in RE-substituted oxide systems for enhanced thermoelectric performance

“…The decrease in resistance is attributed to increased drift mobility and concentration of charge carriers at elevated temperatures [15]. At room temperature minimum ln of resistivity found was 9.60 X m of sample B3, and at 600°C temperature minimum ln of resistivity found was 1.25 X m of sample B2 which was also in good agreement with already reported results [13,[18][19][20] and continuation of our author's previous work [21]. Enhanced electrical conductivity of bismuth cobaltite can be the result of improved grain alignment due to Nd doping [22], The activation energy was also calculated from Arrhenius relation as given in Eq.…”

Synthesis and Characterization of Nd-Doped Calcium Bismuth Cobaltites for Thermoelectric Applications

“…As a radiation source, Cu-Kα with a wavelength of 1.54Å was used with 2θ varying from (20̊ to 80). As a result, X-ray scattering causes a certain diffraction pattern to appear, which reveals the atomic structure of a crystal or material [11]. Even with Neodymium doping, the crystal structure of both samples remained the same because the doped Neodymium takes its position in lattice sites and does not change the crystal structure as shown in fig.…”