The effect of La³⁺ and Nd³⁺ on piezoelectric, dielectric and ferroelectric properties of PZT (Pb(Zr_0.53Ti_0.47)O₃) was studied. The powders were prepared by “wet-chemical” route followed by calcination at 800 ℃ for 4 h. XRD analysis of the calcined powders confirms the tetragonal phase in the undoped PZT, which gradually decreases with the dopant concentration and the appearance of rhombohedral phase simultaneously. SEM study of sintered pellets reveals the decrease in grain size with the increase in dopant concentration beyond 0.02 mol Nd³⁺ and 0.03 mol La³⁺ respectively. The piezoelectric constant (d₃₃) and dielectric properties were maximum for 0.02 mol Nd³⁺ and 0.03 mol La³⁺ respectively. The remnant polarization of La³⁺-doped sample was higher than Nd³⁺-doped sample, and the sample with combined dopants shows intermediate remnant polarization (P_r). Based on the above study, it is concluded that La³⁺ is more effective than Nd³⁺, including in a mixture of La³⁺ and Nd³⁺ dopants.

Manganese tetroxide (Mn₃O₄) nanofibers were prepared by electrospinning homogeneous viscous solution of 20 wt%, 28 wt% and 36 wt% manganese acetate in poly vinyl alcohol (PVA) and calcining the nanofibers at 1000 ℃ for 2 h. Electrospinning was carried out at 9 kV DC with tip to collector distance (TCD) of 7 cm. Thermo gravimetric analysis (TGA) of the fibers indicates the pure phase of manganese oxide above 500 ℃. XRD analysis of calcined (at 1000 ℃) nanofibers indicates the formation of phase-pure tetragonal Mn₃O₄. Scanning electron microscopy (SEM) studies show the fibers cylindrical with the diameters in the range of 100–600 nm and aspect ratio > 1000. In general, the average diameter of the green fibers decreases with the increase in manganese acetate concentration. The diameter of calcined nanofibers is reduced by 34%.