Conclusion
The conventional solid state reaction method is explored in the preparation of Ca4Nb2O9 powder by using CaCO3 from chicken eggshell waste as a starting material. The temperature and soaking time of calcination indicated to have an evident effect on the particle size and phase formation of calcined Ca4Nb2O9 powder. This resulted in the particle size and phase formation of Ca4Nb2O9 depending on the calcination condition. The activation energy calculated by OZAWA methods is 1131728 kJ mol1. This study indicated that CaCO3 from chicken eggshell waste is an alternative starting material for
synthesizing Ca4Nb2O9 powder.