We emphasized on a detailed investigation of the structural, optical, and magnetic properties of pure and Ni-doped SnO₂ nanoparticles (NPs) synthesized by a sol-gel process. An extensive structural study has been carried out using various characterization techniques. The X-ray Diffraction (XRD) spectra show the formation of the single phase tetragonal structure of pure and Ni-doped SnO₂ NPs without any noticeable impurity phase such as NiO. XRD results indicate that the crystallite size of SnO₂ is found to be decreased with Ni doping, which has also been confirmed by the Field Emission Scanning Electron Microscopy study. X-ray Photoelectron Spectroscopy (XPS) measurements displayed a clear sign for Ni²⁺ ions occupying the lattice sites of Sn⁴⁺ in the SnO₂ host which also gives clear evidence for the formation of single phase Sn_1-xNi_xO₂ NPs. The optical analysis shows a significant decrease in the energy gap of SnO₂, i.e., (from 3.71 eV to 3.28 eV) as Ni concentration increases which may be correlated with the core level valence band XPS analysis. Photoluminescence studies show that Ni doping creates oxygen vacancies due to dissimilar ionic radii of Ni²⁺ and Sn⁴⁺. Superconducting quantum interference device measurements revealed that the Ni doped SnO₂ NPs exhibit strong ferromagnetic behavior at room temperature and this analysis has been well fitted with a simple relationship to find out magnetic parameters proposed by Stearns and Cheng et al. Hence, our results demonstrate that Ni-doping has strong impact on the structural, optical, and magnetic properties.

Entropy optimized Bi₂Te₃ based materials achieved a high thermoelectric performance with a figure of merit of 1.7 at 450 K and a maximum conversion efficiency of 8% with a temperature gradient of 225 K.

The new ceramic composite of Ca(Zr_xTi_1-x)O₃ had been prepared using the conventional mixed oxide solid state reaction method. The effects of Zr⁴⁺ ions substation over Ti⁴⁺ ions on the microwave dielectric properties of the CaTiO₃ ceramics were investigated. The phase analysis showed that the specimens Ca(Zr_xTi_1-x)O₃ presented single phase with orthorhombic structure in the range of x = 0.0–0.7 when sintered at 1300 °C for 3 h. The addition of Zr⁴⁺ facilitated the formation of large round-like grains with porous microstructure. The solid solution with x = 0.7 sintered at 1300 °C for 3 h showed a good combination of dielectric properties: ${\mathrm{\epsilon }}_{\mathrm{r}}=64,\text{ Q*f}=3937\mathrm{GHz}$ and ${\rho }_{\mathit{rel}}=81.08\mathrm{\%}$ (at 2.5 GHz).