Laser processing of CaMnO3-based materials for thermoelectric applications

Abstract

Today, a particular interest is given to the oxide-based thermoelectric materials, due to enhanced thermal and redox stability, attractive properties at high temperature, the absence of toxicity, and natural abundance of the constituent compounds. The objective of this work is to assess the possibilities for processing oxide thermoelectrics through laser floating zone (LFZ) method, including identification of the appropriate treatment conditions and main structural and microstructural factors affecting the thermoelectric performance. Known Nb- and La-substituted calcium manganite-based materials, possessing promising thermoelectric properties, were selected as a model system. Detailed structural (XRD) and microstructural (SEM/ EDS) studies were performed for the samples, grown at various pulling rates. The results on electrical conductivity, Seebeck coefficient and thermal conductivity indicate that high thermoelectric performance can be triggered by laser processing. Effects of pulling rate, dopants and thermal treatment to the fibres on these properties are discussed, suggesting that careful optimization of the laser treatment conditions is necessary when seeking high thermoelectric performance in oxides by LFZ processing.