Nano crystalline Zn1-xSmxO, (0.00 ≤ x ≤ 0.10), were prepared by wet chemical coprecipitation method. The effect of samarium doping on the structural, morphological, optical, and magnetic properties of ZnO nanoparticles was examined by X-ray powder diffraction (XRD), Transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), Ultraviolet-visible spectroscopy (UV) and M-H magnetic hysteresis. XRD analysis showed the hexagonal wurtzite structure of ZnO. The absence of Sm2O3 as separate phase may be attributed to the complete dissolving of samarium in ZnO lattice. The lattice parameters (a and c) of Zn1-xSmxO were calculated and they fluctuated with the increase of Sm doping which indicated that the structure of ZnO was perturbed by the doping of Sm. The crystallite size was computed for all the samples using Debye-Scherrer’s method. The crystallite size decreased with the increase of Sm doping. TEM micrographs revealed that the size and the shape of the ZnO nanocomposites were changed by modifying the doping level of samarium. FTIR analysis spectrum confirmed the formation of ZnO phase and revealed a peak shift between pure and Sm-doped ZnO. The band gap energy and Urbach energy were calculated for Zn1-xSmxO, (0.00 ≤ x ≤ 0.10). The band energy gaps of pure and Sm doped ZnO samples are in the range 2.6–2.98 eV. M-H hysteresis inspection, at room temperature, showed that the pure ZnO exhibited a ferromagnetic behavior incorporated with diamagnetic and paramagnetic contributions. Ferromagnetic behavior was reduced for the doped samples with x=0.01 and x=0.04. The samples with x=0.02 and 0.06 ≤ x ≤ 0.10 tend to be superparamagnetic. The saturation magnetization (Ms), the coercivity (Hc), and the retentivity (Mr) were recorded for Zn1-xSmxO, (0.00 ≤ x ≤ 0.10).

Superconducting samples of TlBa 2 CaCu 2−x Sc x O 7−δ with x = 0.0, 0.025, 0.05, 0.1, 0.15 and 0.2 have been prepared via the solid-state reaction technique. The effect of weak magnetic fields up to 4.4 kG on the electrical resistivity of the prepared samples has been studied to investigate the flux motion for this phase. The results reveal a slight shift in the superconducting transition temperature T c and an increase in the superconducting transition width T with increasing magnetic field. The magnetic field has a small effect on the electrical resistivity in the normal state and in the first stage of transition, whereas the change in the second stage of superconducting transition is very large. The experimental data, in the second stage of superconducting transition, fit well with the thermally activated flux creep model and the activation energy U (B) shows a power law dependence on magnetic field as B −β . Also, the transition width is related to the magnetic field according to the relation T α B n . The values of β and n are strongly dependent on the scandium content. The magnetic field and temperature dependence of the activation energy U (B, T ) is found to be U (B, T ) ∼ T B −η , where η = β + n. The critical current density J c (0) and the upper critical field B c2 (0) are calculated, from the above measurements, as a function of scandium content. Finally, the electronic thermal conductivity κ e , estimated from the Wiedermann-Franz law, is reported at different applied magnetic fields for the prepared samples.

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The effect of erbium (Er) doping on the structural, magnetic and mechanical properties of Zn 1−x Er x O, with 0.00 ≤ x ≤ 0.10, samples was studied using X-ray powder diffraction, M-H magnetic hysteresis and digital Vickers microhardness tester, respectively. The samples were prepared by wet chemical co-precipitation method. Vickers microhardness (H v) measurements were carried out at different applied loads (0.25-10 N) and dwell times (t = 10-60 s) to study the mechanical performance of the samples. Experimental results of H v were analyzed using Meyer's law, and modeled according to Hays-Kendall, elastic/plastic deformation, modified proportional specimen resistance (MPSR) and Indentation Induced Cracking models. It was observed that the MPSR model was the most appropriate model for describing the load independent microhardness data of Er-doped ZnO nanoparticle samples. Indentation creep behavior of Zn 1−x Er x O samples was studied at room temperature by measuring the variation of H v with the dwell times (t = 10-60 s) at fixed applied loads F = 1, 5 and 10 N, respectively. The results showed that Er-doped ZnO nanoparticles samples possessed grain boundary sliding and dislocation climbs at low loads followed by dislocation creep for higher loads within the operative creep mechanism.

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