Application of chicken eggshell waste as a starting material for synthesizing calcium niobate (Ca4Nb2O9) powder

This study focused on the possibility of using CaCO3 from chicken eggshell waste as a starting material for synthesizing Ca4Nb2O9 powder via a conventional solid state reaction. The heat behavior of CaCO3 and Nb2O5 raw material mixture was studied by thermogravimetric analysis (TGA). Phase formation of Ca4Nb2O9 was studied as a function of calcination conditions by Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy and X-ray diffraction (XRD). The morphology and microstructure were charaterized via Scanning electron microscope (SEM). The X-ray fluorescence (XRF) results showed that the chicken eggshell contained more than 96.0% of CaCO3 by weight. The XRD pattern peaks matched the peaks of calcite CaCO3 ICDD No. 85-11108 very well. Furthermore, the XRD results and Rietveld refinement analysis confirmed that the purity and single phase of Ca4Nb2O9 corresponded to the monoclinic structure (ICDD: 49-0911) obtained after the calcination process. The non-isothermal kinetic of Ca4Nb2O9 also was investigated by the Ozawa methods. This study indicated that CaCO3 from chicken eggshell waste is an alternative starting material for synthesizing Ca4Nb2O9 powder.