X-ray diffraction and Mossbauer studies on superparamagnetic nickel ferrite (NiFe2O4) obtained by the proteic sol–gel method

Nogueira, N.A.S.; Utuni, V. H. S.; Silva, Yuri Cruz da; Kiyohara, Pedro Kunihiko; Vasconcelos, Igor F.; Miranda, M. A. R.; Sasaki, J. M.

doi:10.1016/j.matchemphys.2015.07.057

Cited by 36 publications

(17 citation statements)

References 31 publications

(24 reference statements)

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“…Furthermore, the surface of the NPs seems to be composed of some distorted or slanted spins that repel the core spins to align the field direction. The values obtained here are in agreement with others reported in the literature [41][42][43] . The inset of Fig.…”

Section: Characterizationsupporting

confidence: 93%

Flexible, Large-Area Organic Solar Cells With Improved Performance Through Incorporation of CoFe2O4 Nanoparticles in the Active Layer

Pereira

Lima²,

Almeida

et al. 2019

Mat. Res.

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Cobalt ferrite (CoFe 2 O 4) nanoparticles (NPs), with an average diameter of about 4-10 nm, were produced by the proteic sol-gel method and successfully doped into the active layer of poly(3-hexylthiophene-2,5diyl) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) organic solar cells. Pristine and CoFe 2 O 4 NPs-doped blends of P3HT:PCBM were dispersed in a mixture of o-xylene:tetralin (1 mg/mL) based non-halogenated solvents and deposited via a semi-industrial blade coating process on flexible substrates to fabricate large area (0.55 cm 2), flexible organic solar cells with inverted configuration. The main focus of this study aims to assess the influence of NPs on the efficiency, stability and lifetime of the produced devices. From the photovoltaic parameters it was observed that the optimization of the bulk-heterojunction through the incorporation of CoFe 2 O 4 NPs resulted in increased short-circuit current density. As a result, the power conversion efficiency of doped devices increased by 10 % when compared with the undoped reference devices. Tests of lifetime and stability were performed using International Summit on OPV Stability (ISOS) protocols ISOS-D-3, ISOS-O-1 and ISOS-L-1. For the duration of the tests (1200 h), the results showed that doped cells presented performances at least comparable with those of reference cells.

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Section: Characterizationsupporting

confidence: 93%

Flexible, Large-Area Organic Solar Cells With Improved Performance Through Incorporation of CoFe2O4 Nanoparticles in the Active Layer

Pereira

Lima²,

Almeida

et al. 2019

Mat. Res.

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“…It could thus be speculated to be due to continuous evaporation and not decomposition. Nogueira et al [58] also observed a weight gain after 600 °C of NiFe 2 O 4 and explained it by formation of oxides, however, the iron is already in oxidation state 3 and cannot be further oxidized. Singh et al [59] also observed a weight gain of Ni 0.5 Zn 0.5 Fe 2 O 4 , however after about 675 °C, but they provided no explanation.…”

Section: Resultsmentioning

confidence: 99%

Thermogravimetry and Mass Spectrometry of Extractable Organics from Manufactured Nanomaterials for Identification of Potential Coating Components

et al. 2019

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Manufactured nanomaterials (MNMs) often have a surface-chemical modification in order to tailor their physicochemical properties, including also powder properties and miscibility. Surface-chemical modifications may influence the toxicological properties of the MNM, but the specific chemistry and extent are rarely described in detail in suppliers’ technical data sheets. Chemical and quantitative information on any surface-chemical treatment, coating and functionalization are required for chemicals registration in Europe. Currently there is no globally accepted and documented approach to generate such data. Consequently, there is a continued research need to establish a structured approach to identify and quantify surface-chemical modifications. Here we present a tiered approach starting with screening for mass-loss during heating in a furnace or thermogravimetric analysis (TGA) followed by solvent extraction, and analysis by several mass spectrometry (MS) techniques depending on the target analytes. Thermal treatment was assumed to be able to quantify the amount of organic coating and MS was used to identify the extractable organic coatings after pressurized liquid extraction (PLE) using methanol at 200 °C. Volatile organic compounds in extracts were identified with gas chromatography and MS (GC-MS), non-volatile organic compounds with liquid chromatography MS (LC-MS), and polymeric compounds with matrix-assisted laser desorption ionization time-of-flight MS (MALDI-TOF-MS). The approach was demonstrated by analysis of 24 MNM, comprising titanium dioxide, synthetic amorphous silica, graphite, zinc oxide, silver, calcium carbonate, iron oxide, nickel-zinc-iron oxide, and organoclay. In extracts of 14 MNMs a range of organic compounds were identified and the main groups were silanes/siloxanes, fatty acids, fatty acid esters, quaternary ammonium compounds and polymeric compounds. In the remaining 10 MNMs no organic compounds were detected by MS, despite the fact an organic coating was indicated by TGA.

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“…It can be seen from Fig.5 and Table.1 that the M s increases with the increasing grain size when the grain size was below micron order of magnitude, which can be attributed to the presence of large amount of surface spin canting in ferrite nanoparticles sintered at low temperatures [30]. The NFO samples in our work show much higher M s values, compared with previous works of NFO prepared by various methods [7,10,[31][32][33][34], which may be connected with the different microstructures as a result of various preparation and sintering conditions.…”

Section: Resultsmentioning

confidence: 41%

Structural, dielectric and magnetic properties of NiFe2O4 prepared via sol–gel auto-combustion method

Sun

Zhang

Wang

et al. 2017

Journal of Magnetism and Magnetic Materials

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Nickel ferrite (NiFe 2 O 4) powders were synthesized via sol-gel auto-combustion method and the corresponding temperature dependence of microstructure, dielectric and magnetic properties have been investigated. Results of XRD and SEM indicate that the NiFe 2 O 4 samples exhibit a typical single phase spinel structure and a uniform particle distribution. The dielectric constant and dielectric loss measurements show strong frequency dependence of all the samples. The peak observed in frequency dependence of dielectric loss measurements shifts to higher frequency with the increasing sintering temperature, indicating a Debye-like dielectric relaxation. The remanent magnetization increases with the increasing grain size while the coercivity is just the opposite. The saturation magnetization can achieve 50 emu/g when the sintering temperature is more than 1000 o C, and the lowest coercivity (159.49 Oe) was observed in the NFO sample sintered at 1300 o C for 2 h.

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X-ray diffraction and Mossbauer studies on superparamagnetic nickel ferrite (NiFe2O4) obtained by the proteic sol–gel method

Cited by 36 publications

References 31 publications

Flexible, Large-Area Organic Solar Cells With Improved Performance Through Incorporation of CoFe2O4 Nanoparticles in the Active Layer

Flexible, Large-Area Organic Solar Cells With Improved Performance Through Incorporation of CoFe2O4 Nanoparticles in the Active Layer

Thermogravimetry and Mass Spectrometry of Extractable Organics from Manufactured Nanomaterials for Identification of Potential Coating Components

Structural, dielectric and magnetic properties of NiFe2O4 prepared via sol–gel auto-combustion method

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