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The present study depicts physicochemical characteristics of Gd3+ modified Fe3O4 nanoparticles synthesized via the sol-gel combustion method. Structural, microstructural, optical, electrical, and magnetic characteristics were investigated. X-ray diffraction studies demonstrated that all the compositions exhibit cubic crystallinity and phase pure crystal structure with space group $$Fd\bar{3}m$$ . FESEM micrographs depicted that the average crystallite size increases from 15.35 nm [x = 0] to 23.74 nm [x = 0.10] with increasing Gd3+ content. FTIR spectra of the compositions show bend at 522 cm− 1 belonging to Fe–O stretching, which confirms the formation of ferrite nanoparticles. Photocatalytic activity of Fe(3−x)GdxO4 nanoparticles with x = 0 and 0.10 was carried out using methylene blue (MB) dye under UV light. Dielectric studies revealed that the dielectric constant decreases due to the incorporation of Gd3+ ion in the Fe3O4 crystal lattice. Negligible coercivity and remnant magnetization revealed the superparamagnetic behavior for all the compositions and it was observed that saturation magnetization decreases with increasing Gd3+ concentration. Magnetic recyclability illustrated the reusability of Gd3+ modified Fe3O4 nanoparticles.

In this report, an environment friendly and cost effective green synthesis method of magnetite nanoparticles (Fe3O4 NPs) was introduced. Fe3O4 NPs were successfully synthesized by green route using Ocimum basilicum leaf extract. The structural investigation of Fe3O4 NPs using X-Ray diffraction technique revealed the cubic crystallinity with Fd3m space group, which was confirmed with an aid of Rietveld refinement. No secondary phases (such as Fe2O3 and FeO) were observed, which confirmed the high purity of synthesized Fe3O4 NPs. The characteristics peak at 3320 cm−1 displayed the phenolic constituents of Ocimum basilicum leaf extract and peak at 665 cm−1 illustrated the Fe–O bending, which confirmed the formation of Fe3O4 NPs. Ocimum basilicum leaf extract mediated Fe3O4 NPs possess spherical morphology with an average particle size ~ 15 nm as depicted by transmission electron microscopy (TEM). The magnetic potential of Ocimum basilicum leaf extract mediated Fe3O4 NPs was also carried out by using a vibration sample magnetometer (VSM), which revealed the superparamagnetic behavior of Fe3O4 NPs. Cytotoxicity of the as-synthesized Fe3O4 NPs nanoparticles was also examined on the human breast cancer cell line, which illustrated the efficacy of the synthesized nanoparticles with a low value of IC50 (~ 17.75 µg/ml). The results displayed the potent anticancerous effect of Ocimum basilicum leaf extract capped Fe3O4 NPs, which made these nanoparticles suitable for a drug-loaded vehicle for the drug delivery system for biomedical applications.

In this report, we adopted an auto-combustion method to synthesize polycrystalline magnetite (Fe3O4) and magnesium ferrites (MgFe2O4) nanoparticles. The synthesized nanoparticles were characterized using techniques such as X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FTIR), Vibration sample magnetometer (VSM) and photoluminescence (PL) spectroscopy. X-ray diffraction profiles of all the synthesized nanoparticles [Fe3O4 (500 °C): FO NPs, MgFe2O4 (500 °C): MFO1 NPs and MgFe2O4 (700 °C): MFO2 NPs] confirmed phase pure crystallinity without any secondary phases such as FeO and Fe2O3, etc. The implementation of Rietveld refinement determined the cubic crystal symmetry with space group $$Fd\stackrel{-}{3}m$$ for all the synthesized nanoparticles. FE-SEM micrographs depicted the pseudo-spherical morphology with an average grain size of 26.18 nm, 51.6 nm, and 69.68 nm for FO NPs, MFO1 NPs, and MFO2 NPs, respectively. FTIR spectra illustrated the appearance of peaks at 1645 cm−1 and 1345 cm−1 which attributes to metal ions (Fe3+/Mg2+). Photoluminescence spectra of synthesized nanoparticles displayed the emission wavelength in a range of 508–521 nm. The values of saturation magnetization for FO NPs, MFO1 NPs, and MFO2 NPs were found to be 34.2 emu/g, 15.3 emu/g, and 28.8 emu/g, respectively. The magnetization of MgFe2O4 nanoparticles increased with increasing calcination temperature (500–700 °C) so as the grain size. It indicated that Mg substitution at A-site of AB2O4-type (MgFe2O4) spinel ferrite not only gave the phase pure crystal structure but also compete with the magnetic properties of Fe3O4 with increasing calcination temperature. MgFe2O4 nanoparticles (calcined at 700 °C) depicted superparamagnetic behavior and can be utilized as a drug delivery agent for biomedical applications.

Polyvinyl pyrrolidone (PVP) capped Zn1−xCrxO (0.000001≤x≤0.1) nanocomposites were successfully synthesized using a simple chemical co-precipitation technique. The synthesized nanostructures were characterized by X-ray powder diffraction (XRD), transmission electron microscope (TEM), energy dispersive X-ray fluorescence (EDXRF), Fourier-transform infrared spectroscopy (FTIR), UV–visible spectroscopy, photoluminescence (PL) and vibrating sample magnetometer (VSM) measurements. The structural characterization by XRD, TEM, FTIR and EDXRF confirmed the formation of wurtzite structure and incorporation of Cr in the ZnO lattice. The photocatalytic activities of as prepared nanocomposites were evaluated by degradation of methylene blue (MB) dye in aqueous solution under UV/sunlight light irradiation. The results demonstrated that Zn1−xCrxO (x=0.0001) nanocomposite effectively bleached out MB, showing as impressive photocatalytic enhancement over pure ZnO and ZnS nanoparticles. This enhanced photocatalytic activity at optimum concentration was attributed to increased absorption ability of light and high separation rate of photoinduced charge carriers on the nanocomposite photocatalyst surface. The VSM measurements showed significant ferromagnetism in Cr-doped ZnO nanostructures and the value of saturated magnetism was found to decrease with increase in Cr content.

Polyvinyl pyrrolidone capped Zn1−xCuxS (0.00001 ≤ x ≤ 0.1) nanocrystals have been synthesized using facile wet chemical co-precipitation method. Crystallographic and morphological characterizations of synthesized materials have been carried out using X-ray diffraction and transmission electron microscope. Diffraction studies reveal the zinc blende crystal structure of synthesized nanomaterials with average crystallite size ~3 nm. Average particle size calculated from electron micrographs is comparable with the average crystallite size, which confirms the formation of single nanocrystals. Photo-catalytic activity potential of synthesized nanomaterials under UV radiation exposure has been tested using methylene blue dye as test contaminant in aqueous media.

Polyvinyl pyrrolidone capped Zn1-x Mn x S (0 ≤ x ≤ 0.1) nanocrystals have been synthesized using wet chemical co-precipitation method. Crystallographic and morphological characterization of the synthesized materials have been done using X-ray diffraction and transmission electron microscope. Crystallographic studies show the zinc blende crystals having average crystallite size approx. 3 nm, which is almost similar to the average particle size calculated from electron micrographs. Atomic absorption spectrometer has been used for qualitative and quantitative analysis of synthesized nanomaterials. Photo-catalytic activity has been studied using methylene blue dye as a test contaminant. Energy resolved luminescence spectra have been recorded for the detailed description of radiative and non-radiative recombination mechanisms. Photo-catalytic activity dependence on dopant concentration and luminescence quantum yield has been studied in detail.