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Microwave combustion technique (MCT) was used to synthesize of spinel Ni1-xSrxFe2O4 (x = 0.0, 0.1, 0.3 and 0.5) nanoparticles (NPs) by employing the fuel L-arginine. The physical characteristics of the as-prepared NPs were obtained by following methods, viz., powder X-ray diffraction (XRD), high-resolution scanning electron microscope (HR-SEM), energy-dispersive X-ray (EDX), UV-visible diffuse reflectance spectra (UV-Vis DRS), Fourier-transform infrared spectra (FT-IR), and vibrating sample magnetometer (VSM) techniques. The diffraction studies revealed that the average crystallite size exists in the band of 14.25 to 27.52 nm. The HR-SEM pictures revealed the agglomerated and spherical morphology of spinel Ni1-xSrxFe2O4 (x = 0 to 0.5) nanoparticles. Elemental analysis ensured the existence of Ni, Sr, O, and Fe ions. The energy band gap of the NPs was observed to exist in the range of 2.95 to 3.39 eV upon varying the concentration of Sr2+ dopant. The broad peaks at 437 cm−1 and 582 cm−1 correspond to octahedral (B-) metal stretching (Ni-O) and tetrahedral (A-) metal stretching (Fe-O) of nickel ferrite respectively. Magnetic results revealed that the prepared NPs are ferromagnetic in nature. The antibacterial activity (ABA) of gram-positive Staphylococcus aureus and Bacillus subtilis and gram-negative Escherichia coli and Klebsiella pneumonia has been investigated using pure and Sr2+-substituted NiFe2O4 NPs. It was found that the improved activity is intensified with smooth Sr2+ doping as it causes a decrease in the grain size.

Zinc sulfide (ZnS) nanoparticles have been successfully prepared by sol–gel precipitation method. The successful formation of cubic structure is ensured by XRD analysis and Debye Scherrer’s equation is used to determine the crystallite size which was found to be 36 nm for ZnS sample annealed at 200 °C. Surface morphology was studied using HRSEM as well as HRTEM and lattice parameters of the samples were obtained from SAED pattern which was found to have close resemblance to values attained from XRD pattern. Further elemental mapping of ZnS nanoparticles is confirmed by EDX studies. Further Kubelka Munk function was employed to estimate the band gap value which was seen lying within 3.58 to 3.64 eV. Further the antibacterial activity of ZnS is investigated and it is found to be an antibacterial agent of Escherichia coli and staphylococcus aurous, further it can be employed as an antimicrobial agent for prohibiting implant linked infections.

The microwave combustion process (MCP) is used to synthesize Mg1-xCaxFe2O4 (0 ≤ x ≤ 0.5) spinel nanoparticles using the fuel l-arginine. Synthesized samples were examined by employing techniques such as XRD, HR-SEM, EDX, DRS-UV, TG-DTA and VSM. The XRD corroborated the constitution of the cubic spinel structure and the average crystallite size was valued to lie in the range of 16.09 to 33.10 nm. The morphology of the Mg1-xCaxFe2O4 (0 ≤ x ≤ 0.5) spinel nanoparticles was observed by HR-SEM. EDX studies confirmed the formation of spinel ferrite structure. Further bandgap values were estimated to be in the range of 1.84 eV to 2.00 eV. TG-DTA studies confirmed weight loss and exothermic transitions. The M-H loops exhibited ferromagnetic behaviour.

In this work, Magnesium-doped zinc aluminate nanoparticles are synthesized using microwave combustion technique by employing L-alanine as fuel. The incorporation of Mg2+ ions plays a pivotal role in influencing the optical, structural, and magnetic properties of zinc aluminate nanoparticles. The synthesized nanoparticle are characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), high-resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis (EDX), diffuse reflectance spectroscopy (DRS), and vibrating sample magnetometer (VSM).The XRD patterns confirmed the formation of single-phase cubic spinel structure of ZnAl2O4 (gahnite). The average crystallite sizes estimated from Debye-Scherrer is found to be in the range of 6 to 12 nm. HR-SEM images revealed the spherical morphology with uniform distributions. The optical bandgap of the synthesized nanoparticles is found to be in the range of 5.45 eV–5.76 eV. Magnetic measurement reveals that pure and doped zinc aluminate nanoparticles have superparamagnetic nature. These obtained results of Zn1-xMgxAl2O4 (0 ≤ x ≤ 0.5) are found to be well suited for optoelectronics, magnetic, and catalytic applications.