Synthesis, structure and properties of the La0.7K0.3MnO3

The mixed-valence manganites La0.7K0.3MnO3 have been synthesized using the citrate route method. The appropriate stoichiometric quantities were dissolved in an aqueous nitric acid solution and the final composition was annealed at high temperature 700 deg. C . The crystalline structure of the samples was verified using X-ray diffraction (XRD), which showed that the polycrystalline compound has a rhombohedral structure. XRD pattern reveals that mixed polycrystalline oxide is attributed to La(OH)3. The presence of the precursor phase forces the formation of the manganite, along with impurities such as lanthanide hydroxide. The resistivity measurements below room temperature provided evidence of an insulating behavior, while the field-dependent magnetization measurements revealed a transition from a ferromagnetic to a paramagnetic phase