Determination of crystal changes on sodium cobaltite (NaCo 2O4) by Reitveld analysis as a suitability function in thermoelectric materials

Abstract

Sodium Cobaltite, NaCo2O4 has been studied extensively as a new thermoelectric material. The cobalt oxide position in each sodium unit cell may determine the power produced by this type of thermoelectric materials. In this study, several set of samples were prepared by adding a fixed amount of cobalt oxide, Co3O4 into various quantity of sodium carbonate, [(1+x)Na2CO3 (where x=0.5, 1.0, 1.5, 2.0, 2.5 and 3.0)] which then sintered at 1000°C for 6 hours. The XRD results show the structure posed the P63/mmc hexagonal structure. Rietveld analysis had been done to determine the crystal parameter. The parameters show that the crystal structure was changed with an addition of sodium carbonate, NaCo2O4 until a limit where the further addition of NaCo2O4 may cause destruction of the structure.