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A one-step microwave-assisted polyol method was used to fabricate FexZn1−xO (x = 0.01, 0.05, 0.10) nanoparticles. Zinc acetate dihydrate, iron (III) acetylacetonate, oleic acid and diethylene glycol were placed in a Teflon-lined reaction vessel. The reaction mixture was heated up to 250 °C for 15 min in a microwave reactor. The surface modification with oleic acid prevented agglomeration of the nanoparticles. The X-ray diffraction analysis revealed characteristics wurtzite hexagonal structure of ZnO and successful incorporation of the Fe dopant into the host crystal lattice. Doping of ZnO by Fe led to bandgap modification as estimated by Tauc plot. The as-prepared nanopowders were dispersed in toluene and mixed with a poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) polymer to make stable homogenous dispersions. Then, the FexZn1−xO/MEH-PPV nanocomposite thin films were prepared by spin coating and used as thin active layers in polymer light-emitting diodes. The thickness of deposited FexZn1−xO/MEH-PPV film was ca. 30 nm and that of reference neat MEH-PPV film was ca. 25 nm. The electroluminescent spectroscopy study showed that direct blending of MEH-PPV with Fe-doped ZnO nanoparticles is a simple and effective approach to significantly increase the luminance intensity of the diode in comparison to the diode fabricated by neat MEH-PPV. [ABSTRACT FROM AUTHOR]

The gadolinium (Gd3+) substituted zinc ferrite nanoparticles (ZnFe2−xGdxO4) for Gd3+ (x = 0.00, 0.05, 0.10, 0.20) have been synthesized by honey mediated sol-gel auto-combustion method. The X-ray diffraction study revealed the formation of spinel ferrite crystal structure. The Raman spectroscopy and Fourier transform infrared spectroscopy study well support the XRD results analysis. The field emission scanning electron microscopy micrograph revealed spherical morphology and grain size around 10-30 nm for ZnFe2−xGdxO4 (x = 0.10) nanoparticles. The presence of Zn2+ and Fe3+ oxidation state in synthesized nanoparticles was confirmed by X-ray photoelectron spectroscopy. Magnetic properties of the Gd3+ substituted zinc ferrite nanoparticles were investigated by vibrating sample magnetometer at room temperature. The conversion of magnetic hysteresis curves from ferromagnetic to a paramagnetic with the substitution of Gd3+ in zinc ferrite nanoparticles was observed. Frequency dependent dielectric constant and ac conductivity measurements revealed that Gd3+ substitution improved the value of dielectric constant and ac conductivity of the Gd3+ substituted zinc ferrite nanoparticles. Further, the existence of two semicircles in Cole-Cole plot demonstrated the role of both grains and grain boundaries to conduction process in synthesized Gd3+ ion substituted zinc ferrite nanoparticles. Furthermore, the grain relaxation time (τg), grain boundary relaxation time (τgb), grain resistance (Rg), grain capacitance (Cg), grain boundary resistance (Rgb) and grain boundary capacitance (Cgb) for synthesized ZnFe2−xGdxO4 (x = 0.00, 0.05, 0.10, 0.20) nanoparticles have been calculated using modulus spectroscopy analysis. [ABSTRACT FROM AUTHOR]