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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]

Graphical abstract Highlights • Original facile microwave-assisted synthesis of Zinc oxide nanoparticles is reported. • Prepared ZnO nanoparticles form stable colloidal dispersions in toluene. • Solution of MEH-PPV polymer and ZnO nanodispersions mix without agglomeration. • Polymer LEDs with MEH-PPV/ZnO nanocomposite active layer were successfully prepared. • The PLEDs with MEH-PPV/ZnO layer exhibited high electroluminescence at low voltage. Abstract Zinc oxide nanoparticles were synthesized via microwave-assisted reactions from a zinc acetate dihydrate. The reactions were performed in diethylene glycol (DEG) at 220 °C and 250 °C while using oleic acid as the surfactant. The ZnO precipitates obtained were washed with methanol and dried or kept as colloidal solutions redispersed in toluene. The size of the nanoparticles ranged from ca. 5 to 12 nm and they could be modified by the concentration of Zn precursor. Different morphologies due to the function of oleic acid concentration were observed. The resulting ZnO nanocolloids were mixed with the poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) polymer to obtain MEH-PPV/ZnO nanocomposites. The nanocomposite layers exhibited optoelectronic properties which were found to be beneficial for being applied as the active layer in the polymer light emitting diodes. The intensity of the electroluminescence of the prepared PLED devices was enhanced by one order of magnitude keeping all other parameters constant and powered as the same operation voltage. As additional step the effect of active layer thickness on optoelectronic performance of PLED devices was investigated as well. [ABSTRACT FROM AUTHOR]

In this work, a facile and green method for gadolinium doped cobalt ferrite (CoFe 2−x Gd x O 4 ; x = 0.00, 0.05, 0.10, 0.15, 0.20) nanoparticles by using ultrasonic irradiation was reported. The impact of Gd 3+ substitution on the structural, magnetic, dielectric and electrical properties of cobalt ferrite nanoparticles was evaluated. The sonochemically synthesized spinel ferrite nanoparticles were characterized by X-ray Diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM). X-ray diffraction (XRD) study confirmed the formation of single phase spinel ferrite of CoFe 2−x Gd x O 4 nanoparticles. XRD results also revealed that ultrasonic irradiation seems to be favourable to achieve highly crystalline single crystal phase gadolinium doped cobalt ferrite nanoparticles without any post annealing process. Fourier Transform Infrared and Raman Spectra confirmed the formation of spinel ferrite crystal structure. X-ray photoelectron spectroscopy revealed the impact of Gd 3+ substitution in CoFe 2 O 4 nanoparticles on cation distribution at the tetrahedral and octahedral site in spinel ferrite crystal system. The electrical properties showed that the Gd 3+ doped cobalt ferrite (CoFe 2−x Gd x O 4 ; x = 0.20) exhibit enhanced dielectric constant (277 at 100 Hz) and ac conductivity (20.2 × 10 −9 S/cm at 100 Hz). The modulus spectroscopy demonstrated the impact of Gd 3+ substitution in cobalt ferrite nanoparticles on grain boundary relaxation time, capacitance and resistance. Magnetic property measurement revealed that the coercivity decreases with Gd 3+ substitution from 234.32 Oe (x = 0.00) to 12.60 Oe (x = 0.05) and further increases from 12.60 Oe (x = 0.05) to 68.62 Oe (x = 0.20). Moreover, saturation magnetization decreases with Gd 3+ substitution from 40.19 emu/g (x = 0.00) to 21.58 emu/g (x = 0.20). This work demonstrates that the grain size and cation distribution in Gd 3+ doped cobalt ferrite nanoparticles synthesized by sonochemical method, is effective in controlling the structural, magnetic, and electrical properties, and can be find very promising applications. [ABSTRACT FROM AUTHOR]

Abstract: The Cu–Ni nanoalloy phase diagram respecting the nanoparticle size as an extra variable was calculated by the CALPHAD method. The samples of the Cu–Ni nanoalloys were prepared by the solvothermal synthesis from metal precursors. The samples were characterized by means of dynamic light scattering (DLS), infrared spectroscopy (IR), inductively coupled plasma optical emission spectroscopy (ICP/OES), transmission electron microscopy (TEM, HRTEM), and differential scanning calorimetry (DSC). The nanoparticle size, chemical composition, and Cu–Ni nanoparticles melting temperature depression were obtained. The experimental temperatures of melting of nanoparticles were in good agreement with the theoretical CALPHAD predictions considering surface energy. [Copyright &y& Elsevier]

• Sonochemical Synthesis of MnFe 2 O 4 single-phase spinel ferrite structure. • Impact of sonochemical time and percentage amplitude of ultrasonic power input. • Cation redistribution with increase of sonication time. • Physical characteristics controlled by sonication synthesis condition for specific application. Herein, we report sonochemical synthesis of MnFe 2 O 4 spinel ferrite nanoparticles using UZ SONOPULS HD 2070 Ultrasonic homogenizer (frequency: 20 kHz and power: 70 W). The sonication time and percentage amplitude of ultrasonic power input cause appreciable changes in the structural, cation distribution and physical properties of MnFe 2 O 4 nanoparticles. The average crystallite size of synthesized MnFe 2 O 4 nanoparticles was increased with increase of sonication time and percentage amplitude of ultrasonic power input. The occupational formula by X-ray photoelectron spectroscopy for prepared spinel ferrite nanoparticles was (Mn 0.29 Fe 0.42)[Mn 0.71 Fe 1.58 ]O 4 and (Mn 0.28 Fe 0.54) [Mn 0.72 Fe 1.46 ]O 4 at sonication time 20 min and 80 min, respectively. The value of the saturation magnetization was increased from 1.9 emu/g to 52.5 emu/g with increase of sonication time 20 min to 80 min at constant 50% amplitude of ultrasonic power input, whereas, it was increased from 30.2 emu/g to 59.4 emu/g with increase of the percentage amplitude of ultrasonic power input at constant sonication time 60 min. The highest value of dielectric constant (ε′) was 499 at 1 kHz for nanoparticles at sonication time 20 min, whereas, ac conductivity was 368 × 10−9 S/cm at 1 kHz for spinel ferrite nanoparticles at sonication time 20 min. The demonstrated controllable physical characteristics over sonication time and percentage amplitude of ultrasonic power input are a key step to design spinel ferrite material of desired properties for specific application. The investigation of microwave operating frequency suggest that these prepared spinel ferrite nanoparticles are potential candidate for fabrication of devices at high frequency applications. [ABSTRACT FROM AUTHOR]