N. S. Negi

Improved dielectric and ferromagnetic properties in Fe-doped PbTiO3 nanoparticles at room temperature

Fe-doped PbTiO3 nanoparticles have been synthesized by chemical route using polyvinyl alcohol as a surfactant. The results indicate that the dielectric constant and magnetization value of these nanoparticles depends upon their size and Fe dopents. The x-ray diffraction analysis, and transmission and scanning electron microscopies show that the particle’s sizes in the specimens lie in the range of 19–30nm. It is observed that the magnetization is enhanced with reduction in particle size. The largest value of saturation magnetization (Ms=41.6×10−3emu∕g) is observed for 1.2mol% Fe dopents. Dielectric constant and dielectric losses are controlled up to 15MHz at room temperature.

Ferromagnetism and ferroelectricity in highly resistive Pb0.7Sr0.3(Fe0.012Ti0.988)O3 nanoparticles and its conduction by variable-range-hopping mechanism

The enhancement in ferromagnetism and ferroelectricity at room temperature for Pb0.7Sr0.3(Fe0.012Ti0.988)O3 (PSFT) nanoparticles is proved by magnetization and polarization hysteresis loop. The x-ray diffraction and micrograph show that the PSFT nanoparticles have distorted tetragonal single phase, and their average particle’s size is 8 nm. The effect of Sr content reduces the particle size, and hence the multiferroic system becomes more resistive, which dominates the superparamagnetic/paraelectric relaxation. The variable-range-hopping conduction mechanism explained the high resistivity of PSFT nanoparticles, which suggests that the room temperature movement of electrons involves short-range order through defect states.

Resistivity dependent dielectric and magnetic properties of Pb(Fe0.012Ti0.988)O3 nanoparticles

High resistivity in nanostructured Pb(Fe0.012Ti0.988)O3 system prepared by using polyvinyl alcohol (PVA) in chemical route is observed. The PVA acts as a surfactant to limit the particle size. The Fe substitution for Ti controls the chemical stoichiometry and reduces the lattice distortion, i.e., c/a ratio, and hence the transition temperature reduces with Fe content. The phase structure, morphology, particle size, dc resistivity, and dielectric and magnetic properties of Pb(Fe0.012Ti0.988)O3 nanoparticles have been characterized by x-ray diffraction, transmission/scanning electron microscopy, source meter, LCR meter, and vibrating sample magnetometer. The results indicate that the nanosize particles have high resistivity, which improves the dielectric constant at high-frequency region and increases magnetization of the specimens. The observed variable-range-hopping conduction mechanism indicates that Fe doping leads to the occurrence of local defect states in the PbTiO3 lattice. The dispersionless dielec...