Synthesis Of NaxCoO2 Thermoelectric Via Citrate-Nitrate Auto Combustion Reaction

Mohd Azam, Muhamad Ammar Farhan Maula (2017) Synthesis Of NaxCoO2 Thermoelectric Via Citrate-Nitrate Auto Combustion Reaction. Project Report. Universiti Teknikal Malaysia Melaka, Melaka, Malaysia. (Submitted)

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Abstract

This study is regarding the synthesis of NaxCoO2 thermoelectric via citrate-nitrate auto combustion reaction method.To get a better purity of NaxCoO2 the composition of Na is being controlled which is ratio from x = 0.1 to 0.9M.Precursor gels of the composition of NaxCoO2 is being heated until it achieves the auto combustion reaction which turned the precursor gels into ashes.After that,the ashes are calcined at 900°C.Then the powder is continued to be pelletized by using compressive machine which is pressed at 14.2 MPa.The size of the pellet is being fixed which is about 10 mm thickness x 2mm diameter.The characterization of the NaxCoO2 is observed by using the x-ray diffraction (XRD) are used to get the crystallinity structure and study the composition of sodium in the NaxCoO2 and to analyze the surface morphology of the NaxCoO2 by means of scanning electron microscopy (SEM).At ratio x = 0.1,0.3 and 0.5 shows the hexagonal structure while x = 0.7 and 0.9 look plate-like regions.Thermogravimetric analysis and differential thermal analysis (TG-DTA) were observed that the precursors gels with ratio x = 0.7 decomposed in a single-step reaction combusted at temperature of around 260 °C.Samples with ratio x = 0.7 appeared in this work to be electrically superconducting as measured using standard four-probe technique.

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