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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, 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.

A systematic investigation is performed to analyze the synergetic effect of Gd3+ substitution and annealing temperature on the fundamental properties of BiFeO3 nanoparticles. Both pure and Gd3+ substituted BiFeO3 nanoparticles were prepared by simple sol-gel method and annealed in two different temperatures (450 °C and 650 °C). The structural transformation of BiFeO3 from rhombohedral to orthorhombic was observed in the X-ray diffraction (XRD) analysis. FE-SEM images were evident enough in showing the decrease in the agglomeration due to effect of substitution, on the other hand increase in annealing temperature resulted in the growth of particle size. The Gd3+ substituted BiFeO3 prepared at 450 °C possesses higher saturation magnetization value as compared to that of pure BiFeO3 and Gd3+ substituted sample prepared at 650 °C which were analyzed in vibrating sample magnetometer (VSM). Increased value of dielectric constant was observed in Gd3+ substituted samples prepared at both 450 °C and 650 °C.

The present work reports study on antimicrobial activity of pure and doped ZnO nanocomposites. Polyvinyl pyrrolidone capped Mn- and Fe-doped ZnO nanocomposites were synthesised using simple chemical co-precipitation technique. The synthesised materials were characterised using transmission electron microscope (TEM), X-ray powder diffraction (XRD), energy dispersive X-ray fluorescence (EDXRF), Fourier transform infrared (FTIR) spectroscopy and ultraviolet (UV) visible spectroscopy. The XRD and TEM studies reveal that the synthesised ZnO nanocrystals have a hexagonal wurtzite structure with average crystalline size ∼7–14 nm. EDXRF and FTIR study confirmed the doping and the incorporation of impurity in ZnO nanostructure. The antimicrobial activities of nanoparticles (NPs) were studied against fungi, gram-positive and gram-negative bacteria using the standard disc diffusion method. The photocatalytic activities of prepared NPs were evaluated by degradation of methylene blue dye in aqueous solution under UV l...

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.

Presence of trace amount of foreign impurities (both metallic and non-metallic) in standard salts used for sample preparation and during the synthesis process can alter the physical and chemical behavior of the pure and doped nano-materials. Therefore, it becomes important to determine concentration of various elements present in synthesized nano-material sample. In present work, the elemental and compositional analysis of nano-materials synthesized using various methods has been performed using photon-atom interaction based energy dispersive x-ray fluorescence (EDXRF) technique. This technique due to its multielement analytical capability, lower detection limit, capability to analyze metals and non-metals alike and almost no sample preparation requirements can be utilized for analysis of nano-materials. The EDXRF spectrometer involves a 2.4 kW Mo anode x-ray tube (Pananalytic, Netherland) equipped with selective absorbers as an excitation source and an LEGe detector (FWHM = 150 eV at 5.895 keV, Canberra, US) coupled with PC based multichannel analyzer used to collect the fluorescent x-ray spectra. The analytical results showed good agreements with the expected values calculated on the basis of the precursor used in preparation of nano-materials.

Zn1−xCo x S (0.00001 ≤ x ≤ 0.1) nanocrystals have been synthesized using facile bottom-up synthesis technique chemical co-precipitation method. Crystallographic and morphological characterizations of synthesized nanomaterials have been done using X-ray diffraction (XRD) and transmission electron microscope (TEM), respectively. XRD studies confirm the formation of zinc blende crystallites having average crystallite size about 3.0 nm, which is in close agreement with the average particle size calculated from TEM micrographs. The photo-catalytic activity potential of synthesized nanocrystals has been tested using methylene blue dye as test contaminant in aqueous media. Photo-catalytic activity dependence on dopant concentration has been described in detail. Moreover, room temperature energy resolved photoluminescence spectra have been also recorded to correlate the various charge carrier recombination and interfacial charge transfer processes.

Abtract Intrinsic and extrinsic semiconductor nanostructures have attracted great attention due to their size tunable photo-physical and photo-chemical properties. In the present paper, polyvinyl pyrrolidone (PVP) capped Zn 1-x Eu x S (0.00001≤x≤0.1) nanocrystals have been synthesized by means of a facile chemical synthesis method. Crystallography and morphology of synthesized materials have been deliberated using X-ray diffraction (XRD) and transmission electron microscope (TEM), respectively. Diffraction and electron micrograph studies reveal that the synthesized materials are zinc blende nanocrystals having average particle size ~3nm. Elemental and compositional analyses of the nanocrystals have been done using energy dispersive X-ray fluorescence (EDXRF) technique. Steady state photoluminescence spectra have been recorded for optical characterization of synthesized nanomaterials. Photocatalytic activity potential of synthesized nanomaterials under UV radiation exposure has been investigated using methylene blue (MB) dye as a test contaminant in aqueous media. Photo-physical and photo-chemical behaviour dependence on doping concentration has been described in detail. Moreover, the sophistication of competition between charge carrier recombination and charge carrier trapping followed by the competition between recombination of trapped carriers and interfacial charge transfer processes have been presented in a fantastic and elaborative way by comparative study of photoluminescence and photo-catalytic activity results.

Background/Objectives: Microwave absorbing materials can be used to reduce electro- magnetic interference. M-type hexaferrites (SrFe12O19 and BaFe12O19) have attracted intensive attention on account of their important applications in microwave absorbing materials. Methods/Statistical Analysis: M-type hexaferrite nanoparticles with a composition of TbxSr1-xFe12O19 (x = 0-0.1) were amalgamted by a chemical method known as co-precipitation method. A successive solid state reaction at different calcination temperatures at fixed holding time has lead to the formation of pure and Tb substituted strontium hexaferrite. The reaction of swaping of Tb cations on the magnetic, structural, and electrical properties of nanoparticles was characterized by X-ray diffraction XRD, FTIR,TEM and VSM. Findings: Microstructure by TEM showed that grains are of extremely fine phase. Identification by XRD confers the single-phase material of nanometeric size. Evaluation on magnetic characteristics for the material showed that coercivity decreased progressively as number of Tb3+ ion increases. Although this was followed by a significant increase in total magnetization. Reflection loss and reflection coefficient and loss tangent for a range of 1-5 KHz were derived which confirms that the material can be considered for high frequency applications.

Nickel-doped barium nanohexaferrites with the chemical formula BaNixFe(12-x)O19 are prepared using the chemical co-precipitation technique. The calcination of the samples is done at 800°C for 4 h. In order to carry out the structural analysis that includes the crystallographic and the morphological investigations, X-ray diffraction and TEM are carried out to govern the phase, structure and the size of the crystal. By the use of Debye–Scherrer equation, the size of the crystallite is calculated to be in the range of 38–100 nm. TEM results reveal the magnetoplumbite structure of the hexaferrites. The M–H curve obtained using the Vibrating Sample Magnetometer computes the magnetic parameters like saturation magnetization, coercivity, remanence and verifies the behaviour of hexaferrites as hard magnetic materials. Further, the effect of variation in calcination temperature is also investigated on the values of magnetic parameters of hexaferrites. In order to carry out the investigations on the electrical properties of hexaferrites, the two-probe method and parallel plate capacitor set-up are used. The values of relative permittivity, dielectric loss and loss tangent are computed as a function of frequency. The values of DC electrical resistance for pure and nickel-doped barium nanohexaferrites are evaluated from the slope of I–V graphs.

Zn 1−x TM x S [(TM: Fe or Ni); (0.00001≤×≤0.1)] nanocrystals have been synthesized using well known bottom-up synthesis technique; colloidal chemical coprecipitation method. Powder X-ray diffractometer and Transmission Electron Microscope (TEM) have been used for crystallographic and morphological characterization. Analysis of recorded broad X-ray diffraction patterns show zinc blende structured crystallites having average crystallite size ∼3nm. Average particle size calculated from the electron micrographs is in close agreement with the average crystallite size calculated from diffraction studies. Room temperature steady state luminescence spectra have been recorded for optical characterization. Detailed description about the radiative and non-radiative recombination mechanism dependence on the dopant concentration has been established from luminescence studies. Photo-catalytic properties of synthesized nanocrystals have been examined by degradation of methylene blue (MB) dye. Luminescence quantum efficiency and photo-catalytic behaviour dependence on the dopant concentration have been studied in detail.

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.