Synthesis and characterisation of zinc oxide nanoparticles for thermoelectric application

In this research, zinc oxide (ZnO) nanoparticles were prepared through a chemical co-precipitation route using zinc acetate dihydrate and sodium hydroxide as the reactants. To study the variation in the properties of the nanoparticles, namely its phase, shape and size, the reaction temperature and stirring rate were varied during the synthesis process. From the X-ray diffraction profiles, the as-synthesised samples were confirmed to be ZnO. Spherical and hexagonal-shaped particles were obtained when the temperature and stirring rate were varied. A rise in the synthesis temperature from 30 to 70 degrees C caused insignificant changes to the average diameter of the particles, although their shape was altered from spherical to hexagonal. When the stirring rate was increased, the average diameter of the particles decreased. The average diameter of the sample calcined at 600 degrees C for 1 hour recorded a slight increase while its X-ray diffraction profile depicted narrower peaks with higher intensity, indicating formation of a more stable phase of ZnO. Further study is needed to elucidate the effects of the particle shape and sizes on the thermoelectric transport properties.