Herein, the structural and magnetic properties of cobalt ferrite (CoFe2O4 [CFO]) nanomaterials obtained from sol–gel auto‐combustion method using different chelating agent (tartaric acid, citric acid, and oxalic acid) are reported. The obtained precursors from the different chelating agents are calcined at 500 °C for 5 h. The X‐ray diffraction (XRD) analysis suggests that all the synthesized samples show the single‐phase spinel ferrite structure without existing any secondary impurity phases. The lattice parameter, cell volume, density, crystallite size, and dislocation density are computed for all the synthesized samples utilizing the XRD data. The irregular‐shaped grains morphology with a homogeneous distribution is observed through scanning electron microscopy study. The sample synthesized by using the tartaric acid as a chelating agent shows a high magnetization value, highest coercivity, and highest anisotropy constant (K) when compared to those of other chelating agents. High grain‐boundary activation energy is also observed for the CFO nanomaterials obtained from the tartaric acid as a chelating agent.

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We report the structure and dielectric properties of Fe0.7Cr1.3O3 nanocrystallites synthesized by co-precipitation method. X-ray diffraction shows that the nanoparticles possess a typical corundum structure and no other impurity phases are observed. These nanoparticles exhibit a high dielectric permittivity (' ~ 103) at room temperature below 1 kHz. The dielectric relaxation follows the thermally activated process with activation energy of 0.226 eV. Both components of grain relaxation and grain boundary relaxation times were extracted from modulus spectra. The internal barrier layer capacitance (IBLC) effect is responsible for observed high dielectric response in these nanoparticles.

We are reporting the synthesis along with magnetic, ac conductivity and dielectric properties of hematite nanocrystallites. The prepared Fe2O3 is crystallizing in corundum structure which belongs to the rhombohedron system with the space group R3-c. The magnetization data shows a typical Morin transition, TN = 265 K for 110 nm crystallites, whereas this transition is decreasing with decrease in crystallite size, TN = 252 K for 33 nm. The value of magnetization is increased with increasing crystallite size. The enhanced dielectric permittivity and ac conductivity were observed in higher hematite crystallite size. The overall dielectric response has revealed conduction mechanism is due to the extrinsic contribution from the dominant Maxwell-Wagner polarization.

Due to the ever-growing challenge of pollutants emitted by vehicles, protection of the environment from the pollutants has become a focus of attention. The rising volume of traffic on our nation's roadways now poses a severe danger to the environment due to hazardous emissions, and the refueling availability and low maintenance of petrol fuel vehicles have prompted many to choose for petrol vehicles. Numerous experts have used a variety of strategies to decrease the amount of emissions produced by vehicles, but this sector still has a great deal of room for advancement. The objective of this work is to compare the emission characteristics of a four-stroke petrol engine with and without a nano zinc oxide (nano-ZnO) encased catalytic converter. The findings indicated that the nano-ZnO coated catalytic converter aided in reducing the CO, CO2, HC and NOx emissions by 41.3%, 71.4%, 48.2%, and 46.7%, respectively