Magnetoresistivity studies for BiPb-2223 phase added by BaSnO3 nanoparticles

Abstract Co-precipitation method and conventional solid-state reaction technique were used to synthesize BaSnO3 nanoparticles and (BaSnO3) x /Bi1.6Pb0.4Sr2Ca2Cu3O10+δ (0 ≤ x ≤ 1.50 wt%) samples, respectively. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and electrical resistivity data were used to characterize BiPb-2223 phase added by BaSnO3 nanoparticles. The relative volume fraction and superconducting transition temperature T c of BiPb-2223 phase were enhanced by increasing BaSnO3 addition up to 0.50 wt%. These parameters were decreased with further increase of x. The resistive transition broadening under different applied DC magnetic fields (0.29–4.40 kG) was analyzed through thermally activated flux creep (TAFC) model and Ambegaokar–Halperin (AH) theory. Improvements of the derived flux pinning energy U, critical current density J c (0) estimated from AH parameter C(B), and upper critical magnetic field B c2 (0), were recorded by adding BaSnO3 nanoparticles up to 0.50 wt%, beyond which these parameters were suppressed. The magnetic field dependence of the flux pinning energy and critical current density decreased as a power-law relation, which indicated the single junction sensitivity between the superconducting grains to the applied magnetic field. Furthermore, the increase in the applied magnetic field did not affect the electronic thermal conductivity κ e above the superconducting transition temperature and suppressed it below T c

Effect of (Sm, Co) co-doping on the structure and electrical conductivity of ZnO nanoparticles

(Sm, Co) co-doped ZnO nanoparticles (Zn _1−2x Sm _x Co _x O), $0.00\leqslant {\rm{x}}\leqslant 0.06,$ have been prepared by the co-precipitation technique. The effect of the dopant ions Sm ^3+ and Co ^2+ on the structural, morphological, and electrical conductivity of ZnO has been studied. XRD analysis shows the substitution of Zn ^2+ ions by the co-doping Sm ^3+ and Co ^2+ ions with the formation of secondary phases as Sm _2 O _3 and Co _3 O _4 upon 0.005 co-doping and above. Raman spectra showed the characteristic mode of the wurtzite structure of ZnO nanoparticles with a vibration assigned to the bound of Co with the donor defects at high doping level of (Sm, Co). The spherical morphology of pure ZnO is transformed into nanorods as the concentration of Sm ^3+ and Co ^2+ increases. From EDX spectra, it was shown that all samples exhibit an excellent compositional homogeneity that verifies the Sm and Co presence as real dopants in ZnO crystalline structure. FTIR spectra show one discrete peak at 417 cm ^−1 with another broad peak at 568 cm ^−1 corresponding to Zn–O stretching, which confirms the formation of the wurtzite structure of the samples. Photoluminescence studies reveal the existence of minor defects in the co-doped samples. The study proposes the suitable use of the samples in the high-efficiency UV light-emitting devices due to the intense UV peaks compared with the lower visible peaks. The excitation dependent PL spectra demonstrated a redshift with increasing the excitation wavelength accounting for the distribution of energetic species in the ground state. The DC electrical conductivity is enhanced with (Sm, Co) co-doping of x = 0.1 due to the formation of thermally activated donor levels

PHYSICAL AND MAGNETIC PROPERTIES OF NANOSIZED MN0.5NI0.5¬FE2-XPRXO4 PREPARED BY CO-PRECIPITATION METHOD

Nanosized Mn0.5Ni0.5Fe2-xPrxO4, x=0.0, 0.02, 0.04, 0.06, 0.08, 0.1 and 0.15 are prepared by co-precipitation method at calcination temperature 650oC for 4 hours. X-ray diffraction patterns show the presence of the cubic (Mn-Ni)- ferrite phase and anti-ferromagnetic a-Fe2O3. The variation in the lattice parameter “a” is due to the replacement of smaller radius ions Fe+3 by larger radius ions Pr+3. Transmission electron micrographs indicate that the particles are spherical in shape. The moderately agglomerated particles are present due to the interaction between the magnetic nanoparticles. UV-visible optical (UV) and Fourier Transform Infrared (FTIR) spectroscopies show a significant change in the absorption bands as the Pr content increases. The calculated values of the optical band gap energies show an increase as the Pr content increases. This is due to the decrease of the particle size. From VSM analysis, it was found that the saturation magnetization (Ms) and the coercivity (Hc) are strongly dependent on Pr content. The results of M-H loop are interpreted in terms of the observed anti-ferromagnetic phase a-Fe2O3, phase core shell interaction and cation redistribution