Fe-doped Nanoparticles Research Articles

Tailoring the upconversion emission and magnetic properties of NaGdF4:Yb, Er by Mg2+ or Fe3+ doping and optical trapping of individual magnetic nanoparticle at NIR 980 nm

This paper presents the upconversion emission and magnetic properties of NaGdF4:Yb, Er nanoparticles separately doped with Fe and Mg in the 10–40% concentration. The XRD analysis validates the structural properties of NaGdF4:Yb, Er nanoparticles with different concentrations of the dopants. The XPS spectra of Fe-doped NaGdF4:Yb, Er and Mg-doped NaGdF4:Yb, Er nanoparticles reveal the presence of the dopants and their valency. The 30%Mg doping resulted in an intense red upconversion emission at 650 nm compared to the Fe-doped NaGdF4:Yb, Er due to the high lifetime of 254 μs for the 4F9/2 → 4I15/2 (660 nm) energy level transitions of Er3+ ion. The Mg-doped nanoparticles showed a 2.7 red-to-green emission intensity ratio, 5.7 for Fe doping at the same 30% concentration and above this doping level, upconversion emission quenching resulted. The room temperature VSM study demonstrated paramagnetic property in the Mg-doped NaGdF4:Yb, Er nanoparticles characterized by negligible coercivity and retentivity with low saturation magnetization. Similar behaviour is also observed for the Fe-doped nanoparticles up to 20% concentration, and it became weak ferromagnetic at a high 30 and 40% dopant. In addition, the present work demonstrated the optical trapping of individual magnetic nanoparticles of 30%Fe-doped NaGdF4:Yb, Er by using a single beam optical tweezer technique under the tightly focused 980 nm diode laser interaction and the estimated trap stiffnesses is 1.85 pN μm−1 W−1. The multifunctional upconversion red emission, magnetic and optical trapping properties obtained in NaGdF4:Yb,Er,30%Fe nanoparticles can be used as a single particle probe in the theragnostic application.

Ferromagnetic transition metal-doped CdS nanoparticles: a comparative study

In the present work, series of ferromagnetic transition metal-doped (Fe, Co) CdS nanoparticles were synthesized via hydrothermal technique. The particles were characterized for structural, morphological, optical and magnetic properties. The X-ray diffraction confirmed the single wurtzite phase for all compositions. The relatively smaller crystallite size (~ 11.50 nm) was obtained with Fe (x = 0.15) compared to Co doping (~ 13.88 nm). The HR-TEM micrographs revealed spherical morphology of nanoparticles with decrease in average particle size. The increase in optical band gap was observed with doping. In photoluminescence spectra, the main emission peak at 529 nm corresponds to green emission due to d-d intra ion transition. The magnetic analysis confirmed room temperature ferromagnetism in all the compositions and highest value of saturation magnetization has been observed for Fe-doped nanoparticles.

Facile photocatalytic reduction of carcinogenic Cr(vi) on Fe-doped copper sulfide nanostructures.

In this study, Fe-doped copper sulfide nanoparticles (NPs) were investigated for the solar-assisted reduction of CrVI ions in raw water. The Fe-doped NPs were synthesized by decomposing copper(ii) N,N-diphenylmethylpiperazinecarbamodithioate via a facile single-step, one-pot solvothermal method in the presence of iron salt. The CrVI photoreduction data were fit to a pseudo-first-order kinetic model and a Langmuir model. The CuS/Cu2S NP reduction ability for CrVI increases with an increase in dopant percentage. The best catalyst (9% Fe-doped) was able to reduce CrVI (10−4 M K2Cr2O7) to CrIII in raw water using an initial amount of 10 mg in 6 min with a reduction efficiency of up to 100%. The photocatalytic activity was examined while varying five different parameters: sunlight, diffused light, change in pH, and changes in the concentration of the catalyst and the temperature. This new approach presents an active, simple, and cost-effective means for wastewater treatment.

The Preparation, Characterization and Photocatalytic Activity of FexCe1-xO2-n Microstructures

CeO2 nanoparticles (undoped and Fe-doped) were synthesized by coprecipitation method with different precipitants (ammonium hydrogen carbonate and sodium carbonate). X-ray diffraction analysis revealed the absence of any impurity phases in all samples. BET (Brunauer, Emmett and Teller) tests showed that the average sizes of the catalysts synthesized with NH4HCO3 and Na2CO3 particles were 6.95 nm to 8.83 nm and 11.09 nm to 16.9 nm respectively. Specific surface area of the particles changed regularly. SEM (scanning electron microscope) revealed that the shapes of CeO2 and Fe-doped nanoparticles (prepared by ammonium hydrogen carbonate) were rodlike, the shapes of CeO2 and Fe-doped nanoparticles (prepared by sodium carbonate) were schistose. UV-Vis spectroscopy showed that the absorption value of catalysts changed as Fe doped. The direct and indirect band gap of catalysts diminished with Fe doping, and the catalysts prepared with Na2CO3 had narrower band gap than the catalysts prepared with NH4HCO3. Fe0.05Ce0.95O2-n synthesized with Na2CO3 has the best catalytic capability of Rhodamine B degradation.

Structural, optical and magnetic investigations on Fe-doped ZnS nanoparticles

We have reported the structural, optical and magnetic properties induced in Fe-doped (Fe = 1, 5 and 10 %) ZnS nanoparticles, synthesized via low temperature chemical route. The elemental composition of Fe-doped ZnS nanoparticles has been confirmed using electron dispersive spectroscopy. The average crystallite size has been found ~10 nm. The wurtzite crystal structure of Fe-doped nanoparticles, confirmed using X-ray diffraction, indicate the lattice parameters, a = 3.84 Ǻ and, c = 6.25 Ǻ for undoped ZnS and, a = 3.75 Ǻ and, c = 6.14 Ǻ for 10 % Fe-doped ZnS nanoparticles. The band gap of the undoped and Fe-doped ZnS nanoparticles was found blue shifted as compared to the bulk counterpart. Blue shift in band gap further increases with increased Fe concentration in ZnS lattice. In photoluminescence (PL) spectra blue emission peak has been observed at 422 nm. The PL intensity has been found decreased with increased Fe doping. The magnetic studies as analyzed from M-H curves, obtained using vibrating sample magnetometer, indicated ferromagnetic behavior at 10 % Fe concentration, and weak ferromagnetic or paramagnetic like behavior at 5 % Fe concentration.