| 1 | Effects of calcination temperature and time on the Ca3Co4O9 purity when synthesized using starch-assisted sol-gel combustion method显示文摘Ca3Co4O9 is a p-type semiconducting material that is well-known for its thermoelectric(TE),magnetic,electronic,and electro-optic properties.In this study,sol–gel autoignition was used to prepare Ca3Co4O9 at different calcination temperatures(773,873,973,and 1073 K)and time(4,6,8,10,12,and 14 h)using starch as a fuel.The phase and microstructure of the prepared Ca3Co4O9 powder were investigated.Thermogravimetry–differential thermal analysis(TGA)confirms that the final weight loss occurred at 1073 K to form Ca3Co4O9 stable powder.The variable-pressure scanning electron microscopy(VP-SEM)images show that the size of powder particles increases from 1.15 to 1.47μm as calcination time increases from 4 to 12 h,and the size remains almost constant thereafter.A similar pattern is also observed on the increment of the crystallite size and percentage of crystallinity with X-ray diffraction(XRD)analysis.The highest crystallinity is found about 92.9%when the powder was calcinated at 1073 K for 12 and 14 h with 458 and 460Åcrystallite size,respectively.Energy dispersive X-ray spectroscopy(EDS)analysis demonstrates that the calcinated powder has a high intensity of Ca,Co,and O with uniform distribution.High-resolution transmission electron microscopy(HRTEM)images prove that there is no distinct lattice distortion defect on the crystal structure. | M.A.MOHAMMED M.B.UDAY S.IZMAN | 2020 | Journal of Advanced Ceramics2020，9，2： | 0 |
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