Narayan Dutt Sharma

Superparamagnetic nanosized perovskite oxide La0.5Sr0.5Ti0.5Fe0.5O3 synthesized by modified polymeric precursor method: effect of calcination temperature on structural and magnetic properties

AbstractThe present investigation reports the synthesis of superparamagnetic La0.5Sr0.5Ti0.5Fe0.5O3 by modified polymeric precursor method and the effect of temperature on its structural and magnetic properties. The structures of the phases, calcined at different temperatures, were refined in the space group Pbnm with orthorhombic setting. The crystallite size and specific surface area during the decomposition process were monitored up to 1100 °C. A pure nanosized La0.5Sr0.5Ti0.5Fe0.5O3 powder with high-specific surface area of 49 m2 g-1 was obtained after calcination at 500 °C, while the crystallite size was found to be 18 nm, which was in good agreement with the grain size (19 nm) obtained from TEM investigations. The field dependence of magnetization (M–H) measurements indicate that all the samples exhibit weak ferromagnetic behavior due to slight canting of the adjacent Fe3+ spins. The value Mr/Ms of nano sample calcined at 500 °C indicates the formation of superparamagnetic phase. Magnetization increase significantly with decreasing particle size, while there is sharp decrease in coercivity.

Synthesis and characterization of half-doped chromium manganite La0.3Dy0.2Sr0.5Mn0.5Cr0.5O3

The half-doped chromium manganite La0.3Dy0.2Sr0.5Mn0.5Cr0.5O3 has been studied by X-ray diffraction and magnetic and transport measurements. The sample was found to be single phase and crystallized with orthorhombic structure in the space group Pnma. Magnetic measurements showed that the ferromagnetic interactions are dominant and the phase follows Curie–Weiss law only in the high-temperature region. The sample is semiconducting and the transport properties are dominated by the adiabatic small polaron hopping mechanism.Graphical abstract

Synthesis, structure, and magnetic properties of the perovskite La0.3Sm0.2Sr0.5Ti0.5Fe0.5O3

Perovskite oxide La0.3Sm0.2Sr0.5Ti0.5Fe0.5O3 has been synthesized by a citrate-gel precursor method. The Rietveld analysis of the XRD data showed that the sample crystallizes with a orthorhombic structure in the space group Pbnm. Magnetic properties suggest that antiferromagnetic interactions are dominant due to Fe3+–O–Fe3+ units.Graphical abstract

Synthesis, structure, and magnetic properties of the perovskite La 0.3 Sm 0.2 Sr 0.5 Ti 0.5 Fe 0.5 O 3

Perovskite oxide La0.3Sm0.2Sr0.5Ti0.5Fe0.5O3 has been synthesized by a citrate-gel precursor method. The Rietveld analysis of the XRD data showed that the sample crystallizes with a orthorhombic structure in the space group Pbnm. Magnetic properties suggest that antiferromagnetic interactions are dominant due to Fe3+–O–Fe3+ units.Graphical abstract