ICT2014 Abstracts

Nanostructured thermoelectrics (TE) materials have proven enhanced efficiencies (figure of merit) due to reduced phonon propagation while conserving moderate electrical conductivity values. Fabrication of TE nanomaterials in large scale is still a challenging task impedes industrial applications. Copper telluride (Cu₂Te) based compounds gained interest due to its large thermoelectric power and superionic conductivity over the temperature range of 400-900K. Cu₂Te has hexagonal crystal structure and it is a direct band gap semiconductor with p-type characteristics. Surfactant free chemical based synthesis was employed to prepare several grams of Cu₂Te compounds. Thermodynamic modelling of desired reaction was conducted to determine the experimental steps. Metal salt precursor reacted with oxalate precipitating agent at controlled pH conditions. As prepared metal oxalate salts were further heat treated as calcination (under synthetic air) and reduction (under 5% H₂) to form the desired crystal phase. Scanning electron microscopy (SEM) coupled with energy dispersive X-ray Spectroscopy (EDS) was used to determine the morphology and the elemental profile of as prepared samples. X-ray diffraction studies were conducted to investigate the crystal phases present. Spark plasma sintering (SPS) was performed to consolidate the nanopowders and nanostructure was preserved with high density of compaction. Temperature dependent TE evaluation on SPS compacted pellets were performed in the temperature range of 350-900K and results are reported in detail.