11 research outputs found
Synthesis of lithium ferrites from polymetallic carboxylates
No full textLithium ferrite was prepared by the thermal decomposition of three polynuclear complex compounds containing as ligands the anions of malic, tartaric and gluconic acid: (NH4)2[Fe2.5Li0.5(C4H4O5)3(OH)4(H2O)2]×4H2O (I), (NH4)6[Fe2.5Li0.5(C4H4O6)3(OH)8]×2H2O (II) and (NH4)2[Fe2.5Li0.5(C6H11O7)3(OH)7] (III). The polynuclear complex precursors were characterized by chemical analysis, IR and UV–Vis spectra, magnetic measurements and thermal analysis. The obtained lithium ferrites were characterized by XRD, scanning electron microscopy, IR spectra and magnetic measurements. The single α-Li0.5Fe2.5O4 phase was obtained by thermal decomposition of the tartarate complex annealed at 700 °C for 1 h. The magnetization value ≈ 50 emu g-1 is lower than that obtained for the bulk lithium ferrite due to the nanostructural character of the ferrite. The particle size was smaller than 100 nm
Relevance of the basicity of MO–Sm2O3 (M = Zn, Mg, Ca, Sr) mixed oxides for the efficiency of methane conversion to C2 + hydrocarbons
No full textJSCS–3779 Original scientific paper Synthesis of lithium ferrites from polymetallic carboxylates
No full textAbstract: Lithium ferrite was prepared by the thermal decomposition of three polynuclear complex compounds containing as ligands the anions of malic, tartaric and gluconic acid: (NH4) 2[Fe2.5Li0.5(C4H4O5) 3(OH) 4(H2O) 2]�4H2O (I), (NH4) 6[Fe2.5Li0.5(C4H4O6) 3(OH) 8]�2H2O (II) and (NH4) 2[Fe2.5Li0.5(C6H11O7) 3(OH) 7] (III). The polynuclear complex precursors were characterized by chemical analysis, IR and UV–Vis spectra, magnetic measurements and thermal analysis. The obtained lithium ferrites were characterized by XRD, scanning electron microscopy, IR spectra and magnetic measurements. The single �-Li0.5Fe2.5O4 phase was obtained by thermal decomposition of the tartarate complex annealed at 700 °C for 1 h. The magnetization value ≈ 50 emu g-1 is lower than that obtained for the bulk lithium ferrite due to the nanostructural character of the ferrite. The particle size was smaller than 100 nm
Structural, Morphological, and Optical Properties of Single and Mixed Ni-Co Aluminates Nanoparticles
No full textA series including single and mixed Ni-Co aluminates was obtained using the precursor method, with malic acid as a ligand. The malate precursors (polynuclear coordination compounds) were isolated and characterized by Fourier Transform Infrared (FTIR), Ultraviolet/Visible/Near Infrared (UV–Vis–NIR) spectroscopy, and thermal analysis. The UV–Vis–NIR spectra of the synthesized complex compounds highlighted the presence of Co2+ and Ni2+ in an octahedral environment. The thermal decomposition of these precursors led to Co1−xNixAl2O4 (x = 0, 0.1, 0.25, 0.5, 0.75, 0.9, and 1) spinels. The effect of Ni2+ substitution on the structure, morphology, and optical properties of the obtained oxides was studied with the help of different characterization tools. XRD, FTIR, and Raman spectra evidenced the formation of the spinel phase. The size of the crystallites and the agglomeration degree of the particles decrease when the nickel content increases. The band gap (BG) value is not significantly influenced by the Ni substitution. The fluorescence spectra recorded for all samples show a similar pattern, but different intensities of the emission bands
Structural and optical properties of un-doped and doped Sr3Al2O6 obtained through the tartarate precursor method
No full textSynthesis of CuGa 2O 4 nanoparticles by precursor and self-propagating combustion methods
No full textCopper gallate spinels, CuGa 2O 4, have been synthesized by two wet chemical routes: precursor method and self-propagating combustion involving a glycine-nitrate system. All complex precursors have been characterized by chemical analysis, infrared spectroscopy (IR), ultraviolet visible spectroscopy (UV-vis), electron paramagnetic resonance spectroscopy (EPR), thermal analysis and scanning electron microscopy (SEM). The copper gallate spinel oxides have been further investigated by X-ray diffraction (XRD), SEM, IR, UV-vis, magnetic measurements and EPR. The crystallite size of the copper gallate was found about 280 Å. © 2012 Elsevier Ltd and Techna Group S.r.l
Soft Chemistry Synthesis and Characterization of CoFe<sub>1.8</sub>RE<sub>0.2</sub>O<sub>4</sub> (RE<sup>3+</sup> = Tb<sup>3+</sup>, Er<sup>3+</sup>) Ferrite
No full textNanosized CoFe1.8RE0.2O4 (RE3+ = Tb3+, Er3+) ferrites were obtained through wet ferritization method. These ferrites were characterized by X-ray diffraction (XRD), scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM/HR-TEM), Fourier transform infrared spectroscopy (FTIR), Mössbauer spectroscopy and magnetic measurements. The XRD results revealed that the average crystallite size is 5.77 nm for CoFe1.8Tb0.2O4 and 6.42 nm for CoFe1.8Er0.2O4. Distribution of metal cations in the spinel structure estimated from X-ray diffraction data showed that the Tb3+ and Er3+ ions occupy the octahedral sites. TEM images indicated the presence of polyhedral particles with average size 5.91 nm for CoFe1.8Tb0.2O4 and 6.80 nm for CoFe1.8Er0.2O4. Room temperature Mössbauer spectra exhibit typical nanoscaled cobalt ferrite spectra in good agreement with XRD and TEM data. The saturation magnetization value (Ms) is 60 emu/g for CoFe1.8Tb0.2O4 and 80 emu/g for CoFe1.8Er0.2O4. CoFe1.8RE0.2O4 nanoparticles showed similar antimicrobial efficacy against the five tested microbial strains, both in planktonic and biofilm state. The results highlight the promising potential of these types of nanoparticles for the development of novel anti-biofilm agents and materials
Synthesis of CoFe2O4 through Wet Ferritization Method Using an Aqueous Extract of Eucalyptus Leaves
No full textThis study explored a new green approach of the wet ferritization method to obtain magnetic cobalt ferrite (CoFe2O4) by using eucalyptus leaves aqueous extract as a reducing/chelating/capping agent. The spinel single cubic phases of prepared samples were proved by powder X-ray diffraction (XRD), Fourier-Transform Infrared (FTIR) and Raman spectroscopy. The average crystallite size is in the range between 3 and 20 nm. The presence of the functional groups coating the obtained material is confirmed from FTIR and thermal analysis. The scanning electron microscopy (SEM) analysis showed a morphology consisting of nanoparticle aggregates. Raman spectroscopy detects the characteristic bands of spinel-type CoFe2O4. Magnetic investigations reveal the formation of ferromagnetic compounds with cubic magnetic anisotropy and a blocking temperature around 140 K, specific for this type of material. The biosynthesized CoFe2O4 could be an attractive candidate for biomedical applications, exhibiting promising antimicrobial and antibiofilm activity, particularly against Gram-negative bacteria and fungal strains
Investigation of nanocrystalline zinc chromite obtained by two soft chemical routes
No full textZinc chromite (ZnCr2O4) nanocrystalline powders were obtained by two different chemical routes: the precursor method and the solution combustion method involving glycine-nitrates. The complex compound precursors, [ZnCr2(NH2CH2COO)8]·9H 2O and [ZnCr2(NH2CH2COOH) 4.5]·(NO3)8·6H2O, were characterized by chemical analysis, infrared spectroscopy (IR), ultraviolet-visible spectroscopy (UV-vis) and thermal analysis. The structure, morphology, surface chemistry and magnetic properties of ZnCr2O 4 powders were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), infrared and Raman spectroscopy (RS), ultraviolet-visible spectroscopy (UV-vis) and magnetic measurements. X-ray diffraction patterns indicated the chromite spinel phase with good crystallinity and an average crystallite size of approximately 18-27 nm. The band gap values ranged between 3.31 and 3.33 eV. The magnetic measurements indicated an antiferromagnetic transition at TN ∼ 17.5/18 K. © 2013 Elsevier Ltd. All rights reserved
Synthesis and Characterization of Chitosan-Coated Cobalt Ferrite Nanoparticles and Their Antimicrobial Activity
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