Synthesis and Characterization of Sr_0.85Pb_0.15Mn_1−xSn_xO₃ Perovskite Manganite Nanostructures: Structural, Electrical, and Magnetic Properties

Manganite with perovskite structure of Sr_0.85Pb_0.15Mn_1−xSn_xO₃ (x = 0.05, 0.10, 0.15, 0.20, and 0.25) nanoparticles was prepared by coprecipitation route and then annealed at 960°C for 10 h. X-ray diffraction (XRD) analysis reveals that all the obtained perovskites crystallize in an orthorhombic structure (pbnm space group) with traces as secondary phases. The crystallite sizes are 62.15, 51.4, 45, 51, and 56.78 nm for Sn0.05, Sn0.10, Sn0.15, Sn0.20, and Sn0.25 samples, respectively. Morphological investigations confirm the presence of fine nanosized particles of no similar shape and a high tendency to agglomerate. Energy-dispersive x-ray spectroscopy (EDS) and scanning electron microscopy (SEM) confirm the presence of consistent and estimated grain sizes with tin content in the grain size range 278, 192, and 238 nm for Sn0.05, Sn0.15, and Sn0.25 samples, respectively. The crystallite size and particle size show a low value for the Sn0.15 sample, indicating the well-incorporated Sn ions in the lattice. The DC electrical conductivity σ_DC data showed the presence of a semiconductor behavior in overall temperature range 303–428 K. The activation energy E_a is estimated for all the samples using the small polaron hopping (SPH) model conduction mechanism to be 0.3, 0.31, 0.36, 0.34, and 0.33 eV for Sn0.05, Sn0.10, Sn0.15, Sn0.20, and Sn0.25 samples, respectively. E_a shows a significant variation around 192-nm particle size. This can be explained in terms of long-range charge ordering (CO) melting around this particle size or the grain boundary associated with that sample's small crystallite and grain size. The best conductivity of 160.84 m⁻¹ Ω⁻¹ is for the Sn0.15 sample due to low crystallite and particle size, which improves grain boundaries and increases E_a. The magnetic field ± 20 kG dependence of magnetization is studied at room temperature. Sr_0.85Pb_0.15Mn_1-xSn_xO₃ nanoparticles behave as paramagnetic, and the suppression of the scattering of the magnetic domain with an applied magnetic field is designated. H_c, M_s, and M_r are estimated and the best H_c = 50.99 G, M_s = 0.49 emu/g, and M_r = 25 × 10⁻⁴ was found for the Sn0.15 sample. According to obtained results, Sn embedded in manganite with excellent electrical and magnetic properties could be considered a promising candidate for electronic devices and storage media applications.