• Mannan, Nurhabibah Nabilah Ab
• Shamsuddin, Suhadir
• Mohamed, Zakiah
• Noh, Mohamad Zaky

Abstract

This paper reports effects of cobalt (Co) doped at Mn-site of Pr0.75Na0.25Mn1-yCoyO3 (y = 0, 0.02 and 0.05) on structure and electrical properties along with the surface morphology. All the samples were synthesized using standard solid state reaction method. Powder X-ray diffraction measurement shows that all samples were crystallized in an orthorhombic structure with Pnma space group. The unit cell volume was decreased suggestively due to the different ionic radius between Mn and Co as Co increases. Resistivity measurement shows that the y = 0 sample exhibits an insulating behavior down to lower temperature and interestingly the metal-insulator (MI) transition was found at 108 K and 84 K for y = 0.02 and y = 0.05 respectively. The shifting of the MI transition to lower temperature indicates a weakening of the double-exchange mechanism. On the other hand, scanning electron microscope (SEM) measurement showed that a different surface morphology was observed for all samples. A different pattern of grain boundaries was observed with increasing of Co content. Grains connection of y = 0 samples was observed slightly denser compare to the y = 0.02 and 0.05 samples in conjunction with incerasing of the value of porosity. This can be suggested due to the successful of doping of Co ions in the compound

Topics

• morphology
• surface
• compound
• grain
• resistivity
• scanning electron microscopy
• crystalline phase
• powder X-ray diffraction
• cobalt
• porosity
• ceramic
• space group