Structural, electro-magnetic and electrical analysis in monovalent doped Nd0.75Na0.25-xKxMnO3 manganites

• Main Author: Razali, Sufia Aqilah
• Format: Thesis
• Language: English; English; English
• Published: 2019
• Subjects: TK3001-3521 Distribution or transmission of electric power
• Online Access: http://eprints.uthm.edu.my/671/

The polycrystalline Nd0.75Na0.25-xKxMn1O3 (x = 0, 0.05 and 0.10) samples were prepared using solid state reaction method. K doped manganites have been investigated to study its effect on crystalline phase and surface morphology as well as electrical transport and magnetic properties. However most of study show inconsistent result regarding to the electrical transport and magnetic properties as well as crystalline phase and morphology study. Thus, further detailed study need to be conducted in order to explain the properties of manganites. The structured properties of the Nd0.75Na0.25-xKxMnO3 manganite have been characterized using X-ray diffraction measurement showing the crystalline phase of samples were single phased and indexed as orthorhombic structure (Pnma space group). The morphological study from scanning electron microscope showed that there were improvements on the grains boundaries and sizes as well as the compactness with K doping. On the other hand, DC electrical resistivity measurement showed all samples exhibit insulating behavior. Analysis of dlnρ/dT-1 vs. T revealed a peak at temperature 210K for x = 0 and the peaks were shifted to the lower temperature around 190 K and 165 K for x = 0.05 and x = 0.1 respectively. Meanwhile, the investigation on magnetic behavior showed all samples exhibit transition from paramagnetic phase to anti-ferromagnetic phase with decreasing temperature and the TN was observed to shift to lower temperature. Apart from that, the electrical analysis; variable range hopping (VRH) model was selected in order to explain the electrical behavior of the samples as the value of R2 is approached to 0.9999 as it has highest value compared to small polaron hoping (SPH) model. In conclusion, the effect of K+ doped on Nd0.75Na0.25-xKxMn1O3 were effected the properties of manganites including the structure, surface morphology, magnetic and electrical due to the different ionic radius and reduction in the distortion of MnO6 octahedral.