scholarly journals Magnetic behavior of Fe-doped of multicomponent bismuth niobate pyrochlore

2021 ◽  
Vol 60 (1) ◽  
pp. 38-46
Author(s):  
Nadezhda A. Zhuk ◽  
Boris A. Makeev ◽  
Sergey V. Nekipelov ◽  
Maria V. Yermolina ◽  
Anna V. Fedorova ◽  
...  
Keyword(s):  
Solid Solutions ◽  
Solid Phase ◽  
Synthesis Method ◽  
Pyrochlore Structure ◽  
Exchange Interactions ◽  
Magnetic Behavior ◽  
Susceptibility Data ◽  
Nexafs Spectroscopy ◽  
Magnetic Dilution ◽  
Paramagnetic Atoms

Abstract Two series of iron-containing solid solutions Bi2Mg1− x Fe x Nb2O9+δ and Bi2MgNb2−2 x Fe2 x O9−δ of pyrochlore structure were obtained by the traditional solid phase synthesis method. The electronic state and character of exchange interactions of iron atoms in solid solutions were investigated by methods of magnetic dilution and NEXAFS-spectroscopy. According to X-ray spectroscopy and magnetic susceptibility data, iron(III) atoms are distributed mainly in octahedral positions of niobium(V) and in a dominant amount are in the charge state of Fe(III) in the form of monomers and exchange-bonded clusters mainly with antiferromagnetic type of exchange. Differences in magnetic behavior of iron-containing solid solutions of both series have been revealed. Antiferromagnetic and ferromagnetic exchange can be realized between iron atoms, which, with increasing concentration of paramagnetic atoms and averaging structure distortions, becomes less significant. The parameters of exchange interactions in clusters and distribution of iron paramagnetic atoms depending on the concentration of solid solutions have been calculated.

scholarly journals Magnetic Behavior and Nexafs-spectroscopy of Bi₂BaNb₂₋₂ₓСo₂ₓO₉₋δ

2019 ◽  
pp. 687-693 ◽  
Author(s):  
Lubov V. Rychkova ◽  
Sergey V. Nekipelov ◽  
Boris A. Makeev ◽  
Vladimir A. Belyy ◽  
Dmitriy S. Beznosikov ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Solid Solutions ◽  
Electron State ◽  
Solid Phase ◽  
Exchange Interactions ◽  
Magnetic Behavior ◽  
Phase Method ◽  
X Ray ◽  
Nexafs Spectroscopy ◽  
Solid Phase Method

The samples of solid solutions of Bi₂BaNb₂₋₂ₓСo₂ₓO₉₋δ composition at x 0:04 were synthesized by the solid-phase method. The electron state and the nature of the exchange interactions of cobalt atoms in the samples were studied by the measurements of magnetic susceptibility and NEXAFS-spectroscopy. The NEXAFS spectra of the solid solutions and the cobalt oxides CoO, Co3O4 were recorded. According to the data of X-ray spectroscopy and magnetic susceptibility, the charge states of cobalt atoms in the solid solutions were identified as Co(II) and Co(III) in the forms of monomers and exchange-bound aggregates with the antiferromagnetic type of exchange.

scholarly journals NEXAFS–Spectra and Magnetic Susceptibility of Nickel and Chromium Doped of Bismuth Niobate

2020 ◽  
pp. 340-348
Author(s):  
Irina E. Vasilyeva ◽  
Sergey V. Nekipelov ◽  
Boris A. Makeev ◽  
Alexey G. Krasnov ◽  
Nadezhda A. Zhuk
Keyword(s):  
Magnetic Susceptibility ◽  
Charge State ◽  
Electronic State ◽  
High Spin ◽  
Solid Solutions ◽  
Exchange Interactions ◽  
High Spin State ◽  
Chromium Oxides ◽  
X Ray ◽  
Nexafs Spectroscopy

The electronic state and character of exchange interactions of nickel and chromium atoms in solid solutions of Bi5Nb3-3xМ3xO15-δ (М-Cr,Ni) was researched by methods of magnetic susceptibility and NEXAFS-spectroscopy. NEXAFS spectra of nickel and chromium oxides were obtained. According to X-ray spectroscopy in solid solutions, chromium atoms are mainly in the charge state of Cr(III), and nickel atoms in the high-spin state of Ni(II) in octahedral coordination. In solid solutions, paramagnetic chromium and nickel atoms are present in the form of monomers and clusters with a common antiferromagnetic type of exchange

scholarly journals Spectral studies of bismuth-containing pyrochlores

2021 ◽  
Vol 2103 (1) ◽  
pp. 012146
Author(s):  
S V Nekipelov ◽  
N A Zhuk ◽  
O V Petrova ◽  
D V Sivkov ◽  
K A Bakina ◽  
...  
Keyword(s):  
Charge State ◽  
Solid Solutions ◽  
Pyrochlore Structure ◽  
Spectral Studies ◽  
Nexafs Spectroscopy ◽  
Cobalt Nickel ◽  
Metal Atoms ◽  
Thermal Stable

Abstract Thermal stable solid solutions of titanates, niobates, and tantalates of bismuth with a pyrochlore structure doped with 3d-metal atoms were studied using XPS and NEXAFS spectroscopy. Based on spectral studies, it was shown that the manganese, cobalt, nickel and copper atoms in these solid solutions have mainly charge state +2 and iron atoms – charge state +3.

scholarly journals Phase Transformations, Magnetic Susceptibility and NEXAFS-Spectra of Cobalt-Doped Solid Solutions of Bismuth Orthoniobate

2020 ◽  
pp. 89-98
Author(s):  
Nadezhda A. Zhuk ◽  
Lubov V. Rychkova ◽  
Sergey V. Nekipelov ◽  
Boris A. Makeev
Keyword(s):  
Magnetic Susceptibility ◽  
Phase Transformation ◽  
Phase Transformations ◽  
Electronic State ◽  
Solid Solutions ◽  
Electron State ◽  
Exchange Interactions ◽  
X Ray ◽  
Nexafs Spectroscopy ◽  
Charge States

The electron state and the nature of the exchange interactions of cobalt atoms in BiNb1-xСoxO4-δ solid solutions of triclinic and orthorhombic modifications were studied using the magnetic susceptibility and NEXAFS-spectroscopy. In order to determine the electronic state of cobalt atoms, the solid solutions and oxides of cobalt CoO, Co3O4 were studied by NEXAFS-spectroscopy. The X-ray spectroscopy and the study of the magnetic susceptibility of the solid solutions revealed the presence of the monomers and exchange-related clusters of cobalt with the Co(II) and Co(III) charge states characterized mostly by the antiferromagnetic type of exchange. The cobalt containing solid solutions allowed us to confirm the reversibility of the α↔β-BiNbO4 phase transformation

scholarly journals Collective Magnetic Behavior of 11 nm Photo-Switchable CsCoFe Prussian Blue Analogue Nanocrystals: Effect of Dilution and Light Intensity

2021 ◽  
Vol 7 (7) ◽  
pp. 99
Author(s):  
Linh Trinh ◽  
Eric Rivière ◽  
Sandra Mazerat ◽  
Laure Catala ◽  
Talal Mallah
Keyword(s):  
Magnetic Susceptibility ◽  
Light Intensity ◽  
Prussian Blue ◽  
Magnetic Behavior ◽  
Magnetic Interaction ◽  
Light Irradiation ◽  
Prussian Blue Analogue ◽  
Magnetic Susceptibility Data ◽  
Susceptibility Data

The collective magnetic behavior of photoswitchable 11 nm cyanide-bridged nanoparticles based of the Prussian blue analogue CsCoFe were investigated when embedded in two different matrices with different concentrations. The effect of the intensity of light irradiation was studied in the less concentrated sample. Magnetization studies and alternating magnetic susceptibility data are consistent with a collective magnetic behavior due to interparticle dipolar magnetic interaction for the two compounds, even though the objects have a size that place them in the superparamagnetic regime.

scholarly journals Synthesis of Ce1−xPdxO2−δ Solid Solution in Molten Nitrate

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 640
Author(s):  
Hideaki Sasaki ◽  
Keisuke Sakamoto ◽  
Masami Mori ◽  
Tatsuaki Sakamoto
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Solid Solutions ◽  
Photoelectron Spectroscopy ◽  
Synthesis Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Co Precipitation ◽  
Ionic States

CeO2-based solid solutions in which Pd partially substitutes for Ce attract considerable attention, owing to their high catalytic performances. In this study, the solid solution (Ce1−xPdxO2−δ) with a high Pd content (x ~ 0.2) was synthesized through co-precipitation under oxidative conditions using molten nitrate, and its structure and thermal decomposition were examined. The characteristics of the solid solution, such as the change in a lattice constant, inhibition of sintering, and ionic states, were examined using X-ray diffraction (XRD), scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM−EDS), transmission electron microscopy (TEM)−EDS, and X-ray photoelectron spectroscopy (XPS). The synthesis method proposed in this study appears suitable for the easy preparation of CeO2 solid solutions with a high Pd content.

Magnetic Ion Exchange Interactions in NiO—MgO Solid Solutions

ChemInform ◽  
2006 ◽  
Vol 37 (21) ◽  
Author(s):  
N. Mironova-Ulmane ◽  
V. Skvortsova ◽  
A. Kuzmin ◽  
U. Ulmanis ◽  
I. Sildos ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Solid Solutions ◽  
Exchange Interactions ◽  
Magnetic Ion

Thermodynamical study of (CaGa2S4)x(BaGa2S4)1−x solid solutions

2021 ◽  
pp. 2150469
Author(s):  
T. G. Naghiyev ◽  
R. M. Rzayev
Keyword(s):  
Free Energy ◽  
Solid Solutions ◽  
Calculation Method ◽  
Solid Phase ◽  
Ternary Compounds ◽  
Free Energy Of Formation ◽  
Concentration Dependences ◽  
Solid Phase Reactions ◽  
Two Phases ◽  
Energy Of Formation

The solid solutions of [Formula: see text] were synthesized by solid-phase reactions from powder components of CaS, BaS, and Ga2S3. The temperature-concentration dependences of the Gibbs free energy of formation of [Formula: see text] solid solutions from ternary compounds and phase diagrams of the CaGa2S4–BaGa2S4 were determined by a calculation method. It was revealed that continuous solid solutions are formed in these systems. The spinodal decomposition of [Formula: see text] solid solutions into two phases is predicted at ordinary temperatures.

scholarly journals Dendrimeric Poly(Epsilon-Lysine) Delivery Systems for the Enhanced Permeability of Flurbiprofen across the Blood-Brain Barrier in Alzheimer’s Disease

2018 ◽  
Vol 19 (10) ◽  
pp. 3224 ◽  
Author(s):  
Shafq Al-azzawi ◽  
Dhafir Masheta ◽  
Anna Guildford ◽  
Gary Phillips ◽  
Matteo Santin
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Blood Brain Barrier ◽  
Solid Phase ◽  
Synthesis Method ◽  
Delivery Systems ◽  
Brain Barrier ◽  
Target Cells ◽  
Target Tissue ◽  
Blood Brain

Alzheimer’s disease (AD) is a progressive brain disorder and age-related disease characterised by abnormal accumulation of β-amyloid (Aβ). The development of drugs to combat AD is hampered by the lack of therapeutically-active molecules able to cross the blood-brain barrier (BBB). It is agreed that specifically-designed carriers, such as dendrimers, could support the drug penetration across the BBB. The aim of this study was to design biocompatible and biodegradable dendrimeric delivery systems able to carry Flurbiprofen (FP), as drug for AD treatment, across the BBB and liberate it at the target tissue. These dendrons were synthesised using solid-phase peptide synthesis method and characterised by mass spectrometry and fourier-transform infrared spectroscopy (FTIR). The results revealed successful synthesis of dendrons having FP been integrated during the synthesis at their branching ends. Cytotoxicity assays demonstrated the biocompatibility of the delivery systems, whereas HPLC analysis showed high percentages of permeability across an in vitro BBB model for FP-integrated dendrons. Results also revealed the efficiency of drug conjugates on the γ-secretase enzyme in target cells with evidence of eventual drug release by hydrolysis of the carrier. This study demonstrates that the coupling of FP to dendrimeric delivery systems can successfully be achieved during the synthesis of the poly(epsilon-lysine) macromolecules to improve the transport of the active drug across the BBB.

scholarly journals Microstructure features of the BST/(Mg, Ln)-ceramic

2021 ◽  
pp. 2160005
Author(s):  
K. P. Andryushin ◽  
A. V. Nagaenko ◽  
S. V. Khasbulatov ◽  
L. A. Shilkina ◽  
E. V. Glazunova ◽  
...  
Keyword(s):  
Solid Solutions ◽  
Solid Phase Synthesis ◽  
Solid Phase ◽  
Functional Materials ◽  
Ceramic Technology ◽  
Phase Synthesis ◽  
Fine Grained ◽  
Average Grain Size ◽  
Crystallite Sizes ◽  
Fine Grained Structure

Solid solutions of the composition Ba[Formula: see text](Mg, Ln)[Formula: see text]Sr[Formula: see text]TiO3 ([Formula: see text] = 0.01; 0.025; 0.04; [Formula: see text] = 0.20; 0.50; 0.80; Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tu, Yb) were prepared by two-stage solid-phase synthesis followed by sintering using conventional ceramic technology. The influence of rare-earth elements on the microstructure of the prepared ceramic samples was investigated. It was found that regardless of the type of modifiers introduced, the grain landscape of the studied solid solutions with different amounts of SrTiO3 is refined (in the initial system, the average grain size, [Formula: see text], at [Formula: see text] = 0.20 is 6 [Formula: see text]m; at [Formula: see text] = 0.50 is 4 [Formula: see text]m; at [Formula: see text] = 0.80 is 18 [Formula: see text]m) to crystallite sizes not exceeding (2–3) [Formula: see text]m, and compacted. The using of mechanical activation procedures leads to an even greater decrease in the size and an increase in the density of ceramics. The increasing in the concentration of modifiers in each group (within the considered range of dopant variation) against the background of such a fine-grained structure has little effect on the dynamics of changes in [Formula: see text]. It is concluded that it is advisable to use the data obtained in the development of functional materials based on BST/(Mg, Ln) and devices with the participation of these compositions.

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