STRUCTURE AND MAGNETIC PROPERTIES OF Mn–Zn-FERRITES

Synthesis conditions, structure and magnetic properties of Mn-Zn-ferrites prepared by spray pyrolysis of solutions of manganese, zinc and iron nitrates have been considered. The applied technique provides low-temperature (650 °C) obtaining highly dispersed (7-8 nm) powder of Mn0.5Zn0.5Fe2O4 ferrite with a narrow size distribution. Synthesis of Mn0.5Zn0.5Fe2O4 at low temperature avoids MnII → MnIII oxidation reaction that influences the ferrite properties. IR data collected from the ferrite samples obtained both in air and in N2 ambient indicate their high structural and concentration homogeneity. Magnetic measurements confirm single-phase structure of the Mn0.5Zn0.5Fe2O4 powders and give no evidence of the presence of individual iron oxide phases. Curie temperature (375-380 K) is consistent with the theoretically calculated value for Mn1-xZnxFe2O4 (x = 0.5) (Tc = 365÷385 K). Parameters of Moessbauer spectra of the ferrites are typical of FeIII state in oxide solid solutions with a considerable ionicity contribution in Fe-O bonds (δ = 0.33÷0.34 mm/s). FeII state was not revealed by Moessbauer spectroscopy that indicates the absence of FeIII → FeII reduction accompanying the MnII → MnIII oxidation process

Silver(I) complexes with phenolic Schiff bases: Synthesis, anti-bacterial evaluation and interaction with biomolecules

Novel Ag(I) complexes (2a–2c) with phenolic Schiff bases were synthesized using 4,6-di-tert-butyl-3-(((5-mercapto-1,3,4-thiadiazol-2-yl)imino)methyl)benzene-1,2-diol (1a), 4,6-di-tert-butyl-3-(((4-mercaptophe­nyl­)­imino)­methyl)benzene-1,2-diol (1b), and 4,6-di-tert-butyl-3-(((3-mercaptophenyl)imino)methyl)­benzene-1,2-diol (1c). They were examined by elemental analysis, FT-IR, UV-Vis, 1H-NMR spectroscopy, XRD, cyclic voltammetry, conductivity measurements, and biological methods. The complexes are characterized by distorted geometry of the coordination cores AgN2S2 (2c), AgNS (2b) and AgS2 (2a). These stable complexes were not typified by the intramolecular redox reaction in organic solvents resulting in the formation of silver nanoparticles (AgNPs). Antibacterial activity of 1a–1c and 2a–2c was evaluated in comparison with AgNPs and commonly used antibiotics. All the complexes were more active than the ligands against the bacteria tested (14), but they were less active than AgNPs and commonly used antibiotics. Both 1a–1c and their complexes 2a–2c exhibited the capability for the bovine heart Fe(III)-Cyt c reduction. The ligands 1b and 1c were characterized by the highest reduction rate among the compounds under study, and they showed a higher reducing ability (determined by cyclic voltammetry) as compared with that of their Ag(I) complexes 2b and 2c

HETERO-STRUCTURIZED -Fe2O3-In2O3 NANOCOMPOSITE OBTAINED BY SOL-GEL APPROACH

Sol-gel technology was used to prepare heterogeneous Fe2O3-In2O3 nanocomposite consisting of -Fe2-xInxO3 solid solution and two modifications of -Fe2O3 – cubic (C--Fe2O3) and tetragonal (Q--Fe2O3), which are active in adsorption and catalytic processes

A study on the carbohydrate and nitrogen metabolism in Prunus Persica

Thesis (Ph. D. (Agric.)) -- University of Stellenbosch, 1980.Full text to be digitised and attached to bibliographic record

EFFECT OF -Fe2O3/In2O3 NANO-HETEROSTRUCTURE ON ITS SENSITIVITY TO METHANE

Structural features of thin-film γ-Fe2O3/In2O3 hetero-junctions and their gas-sensing features has been studied. Two mechanisms of adsorbed CH4 molecule effect on electric conductivity of the layers depending on operating temperature were propose

EFFECT OF -Fe2O3/In2O3 NANO-HETEROSTRUCTURE ON ITS SENSITIVITY TO METHANE

Structural features of thin-film γ-Fe2O3/In2O3 hetero-junctions and their gas-sensing features has been studied. Two mechanisms of adsorbed CH4 molecule effect on electric conductivity of the layers depending on operating temperature were propose

Advanced Metaloxide Nanomaterials for Gas Sensors with Controlled Properties

Sol-gel approach based on inorganic metal precursors was used to obtain Fe2O3−In2O3 nanocomposites with different microstructure and grain size. The synthesis conditions, which result in the formation of metastable γ-Fe2O3 phase, were revealed. This phase stabilized in the Fe2O3−In2O3 composites was found to be more active in adsorption and catalysis as compared to thermodynamically stable α-Fe2O3. The Fe2O3−In2O3 compositions suitable for the selective detection of O3, NO2 and C2H5OH were proposed

HETERO-STRUCTURIZED -Fe2O3-In2O3 NANOCOMPOSITE OBTAINED BY SOL-GEL APPROACH

Sol-gel technology was used to prepare heterogeneous Fe2O3-In2O3 nanocomposite consisting of -Fe2-xInxO3 solid solution and two modifications of -Fe2O3 – cubic (C--Fe2O3) and tetragonal (Q--Fe2O3), which are active in adsorption and catalytic processes

STRUCTURAL FEATURES AND MAGNETIC PROPERTIES OF γ-Fe2O3–SiO2 NANOCOMPOSITES

Fe2O3–SiO2 composites containing γ-Fe2O3 nanoparticles in an amorphous SiO2 matrix have been prepared by the inorganic sol-gel method. Structure of the samples annealed at different temperatures was characterized by TEM, XRD, EPR and IR spectroscopy. Magnetic measurements were carried out using the SQUID magnetometry technique

MICRO- AND NANO-STRUCTURE AND SURFACE STATE OF SrFe12O19 GRAINS

The differences in micro-structure and chemical composition between grains and grain boundaries of a magnetic material based on SrFe12O19 have been established by XRD, XPS, Auger spectroscopy, SEM and EDXA. The indicated techniques allowed to reveal the irregularities of granular hexagonal structure of the ferrit