Electrical and thermoelectric properties of surfactant-assisted calcium cobalt oxide nanoparticles

We are in need of clean, cost-effective and renewable energy sources because of the energy crisis and global warming. Thermoelectric technology provides the solution for this problem with abundant advantages like less toxicity, solid state operation, maintenance free operation, no moving parts, no chemical reactions and absence of global warming gases. Thermoelectric devices convert irrecoverable thermal energy into electricity via Seebeck effect and vice versa via Peltier effect. The conversion efficiency is measured by a dimensionless figure of merit. Perovskite mesoporous calcium cobalt oxide nanoparticles are promising thermoelectric oxides at elevated temperature with monoclinic structure have been synthesized by sol gel hydrothermal method. The systematic studies revealed the impact of poly vinyl pyrrolidone as a capping agent on the particle size of the nanoparticles. The prepared nanoparticles were characterized by thermal analysis, X-ray diffraction, Raman analysis, scanning electron microscope with energy dispersive analysis, transmission electron microscopy with selected area diffraction and thermoelectric studies. Pure and poly crystalline calcium cobalt oxide nanoparticles were obtained and its average particle size were calculated by the Scherrer formula. Raman analysis showed the vibrational modes at low frequencies related to calcium and cobalt whereas modes observed at higher frequencies are associated with lower atomic mass element oxygen. The particle size increases with increasing the concentration of the capping agent but when the concentration overheads the level then the particles get agglomerated. The morphology, size and shape of the nanoparticles are measured by HRTEM with SAED. Thermoelectric properties were measured for the capping agent optimized sample between ambient temperature and 600 °C.