Synthesis of polycrystalline CuCrO2 using sol-gel and solid-state reaction method

CuCrO2 has a delafossite structure that has the potential to be a thermoelectric material. In this study, we synthesize polycrystalline CuCrO2 using sol-gel and solid-state reaction methods. Urea self-combustion reaction has been used to get the CuCrO2 phase at low temperature for sol – gel method. In this method, a precursor solution was prepared by mixing an aqueous solution of mixed metal (Cu-Cr) nitrates and urea in stoichiometric proportions. The urea-mixed precursor solution was first heated in a beaker to evaporate excess water, and at 300 °C he oven-dried for 3 h. The resulting powder was calcined and pressed into a pellet of 10 mm diameter and then sintered at 1100 °C for 10 h. Solid state reaction method, stoichiometric calculation of CuO and Cr2O3 powders were used as starting materials. These powders were calcined at 1000 °C for 10 h. The calcined powders were pressed into a pellet of 10 mm diameter and then sintered at 1050 °C for 10 h. The morphology of samples showed grain size of the sol-gel method was smaller than the solid state method and from EDX map evidence of the presence of Cu, Cr, and O all over the samples. Based on XRD the samples with the solid-state method have a single phase of CuCrO2 with FWHM (Full Width Half Maximum) value of 0.182 at the main peak, whereas the samples with the sol-gel method still appeared impurities peak and FWHM value of 0.161. These results showed solid-state method led to the forms of single phase, bigger particle size, higher composition, and better crystallization of CuCrO2.