In this study, we reported the synthesis of pure ZnO and Mg‐doped ZnO (Mg‐ZnO) nanoparticles by simple co‐precipitation method and studied the ethanol sensing activity of the synthesized nanostructures. XRD analysis illustrates that the synthesized ZnO and Mg‐doped ZnO nanoparticles (NPs) possess hexagonal wurtzite structure and the average crystallite size is calculated to be 29 nm and 33 nm, respectively. The FT‐IR spectra of pure and Mg‐doped ZnO NPs confirm that the presence of bands appeared near 400 cm^-1 for Zn‐O and the bands at 622 cm^-1 can be attributed to Mg‐O stretching modes. The band gap energy estimated from the absorption spectra for ZnO and Mg‐ZnO NPs, respectively, at 3.26 eV and 3.32 eV, displays the considerable optical property. Further, we observed that the UV‐Vis spectroscopic data exhibits high absorbance in the UV range for the prepared samples. The SEM images clearly display the needle‐like morphology of the synthesized samples. Dynamic light scattering analysis shows average particle size of 110 nm. The ethanol sensing measurements were carried out with 100 ppm concentration, and the linear responses from ZnO and Mg‐ZnO NPs‐based sensors are detected in the working temperature of 350°C. The obtained results demonstrated that the synthesized Mg‐ZnO nanostructures have improved conductivity with larger active surface area for the most promising application in the ethanol sensing activity.

Chromium(III)-doped nickelferrite nanoparticles, with the general formula Ni_0.5Co_0.5Cr_xFe_2−xO₄ (x0.0, 0.10, and 0.20), were prepared by the solgel method. The prepared samples were sintered at 700C for 5hr. The XRD result showed that the prepared samples are in single-phase partially inverse cubic spinel ferrite structures with space group Fd3m. From the XRD characterization, the average crystallite size for all samples decreased from 39.54 to 30.42nm and the lattice parameters are found to be 0.8324, 0.8320, and 0.8314nm for x0.0, 0.10, and 0.20, respectively. The energy dispersive X-ray (EDX) spectroscopy analysis confirmed the presence of all ions as per the stoichiometric ratios. The vibrating sample magnetometer measurements revealed that the saturation magnetization (M_s), remnant magnetization (M_r), and coercive fields are found to be decreased with increasing concentration of Cr³⁺ ions. The UVvis spectroscopy analysis showed that the energy bandgap (E_g) increased with increasing the concentration of Cr³⁺ ion from 1.61 to 1.96eV. The Fourier transform infrared spectra show the two main absorption bands at 407424cm⁻¹ and 547588cm⁻¹ corresponding to stretching vibrations of metaloxygen in the octahedral and tetrahedral sites, respectively.