Role of Zn And Polyaniline In Magnetic Nanocomposites And Enhanced Arsenic Adsorption Capacity In Wastewater

Polyaniline/Fe0.90Zn0.10Fe2O4 (PANI/Zn0.10Fe2.90O4) nanocomposites were synthesized by a chemical method and an onsite polymerization method. XRD patterns showed that the Zn0.10Fe2.90O4 grain size about 12 nm, while TEM image showed grain size from 10 to 20 nm. The results of Raman spectra and DTA analyses showed that PANI participated in part of the PANI/Zn0.10Fe2.90O4 nanocomposite samples. The grain size of PANI/Zn0.10Fe2.90O4 samples measured by SEM was about 35–50 nm. These results demonstrated the shell–core structures of the nanocomposite material. The magnetization measurements at room temperature showed that in 1250 Oe magnetic field, the saturation magnetic moment of PANI/Zn0.10Fe2.90O4 samples decreased from 71.2 to 42.3 emu/g when the PANI concentration increased from 0 % to 15 %. The surface area and porous structure of nanoparticles were investigated by the BET method at 77 K and a relative pressure P/P0 of about 1. The arsenic adsorption capacity of the PANI/Zn0.10Fe2.90O4 sample with the PANI concentration of 5 % was better than that of Fe3O4 and Zn0.10Fe2.90O4 in a solution of pH 7. In the solution with pH P14, the arsenic adsorption of magnetic nanoparticles was insignificant. Due to substitution of Fe ions by Zn transition metal and coating polyaniline, these materials could be reabsorbed and reused.

Photoelectric and Magnetic Properties of Boron Nitride Nanosheets with Turbostratic Structure and Oxygen Doping

Turbostratic and oxygen doping (3.7 atom % ) hexagonal boron nitride nanosheets (TO-BNNSs) with abundant defect sites, were synthesized by pyrolyzing the mixture of melamine cyanurate and boric acid. Systematic analyses reveal a highly disordered structures and covalent oxygen-doping in the TO-BNNSs. These features endow the product with increased unpaired electrons, localized charge asymmetry and spin polarization. While compared with bulk h-BN, the optical bandgap of TO-BNNSs drop down to ~5.2 from ~5.7 eV, dielectric constant raised from ~2.1 to ~2.4, the saturation magnetic moment increased from ~0.011 to ~0.033 emu/g, and the coercivity enlarged from ~73.56 to ~367.39 Oe. These results suggest that h-BN materials with turbostratic structure and heteroatom-doping have extensive application prospect in the fields of nanoscale optics, electronics and magnetics.

Crystal structure and magnetic properties of ternary Al3CoNd2 compound

A ternary compound Al3CoNd2 was synthesized and its crystal structure parameters were determined by the Rietveld refinement method based on powder X-ray diffraction data. Results show that the compound crystallizes in the MgCu2-type structure (cubic Laves C15 phase, space group $Fd\bar{3}m$ ), with the lattice parameter of a = 7.8424(2) Ǻ, unit-cell volume of V = 482.33 Å3, and calculated density of Dcalc = 5.90 g.cm−3. The residual factors converge to Rp = 0.1024 and Rwp = 0.1287. The reference intensity ratio value obtained experimentally is 3.03. Magnetic susceptibility measurements indicate an agreement with the Curie–Weiss law in the temperature range of 385–450 K, and paramagnetic Curie temperature of θp = 379.9 K. Both rare-earth elements and cobalt ions contribute to the paramagnetic moment. The saturation magnetic moment and magnetic hysteresis loop were measured for the Al3CoNd2 compound at various temperatures. Results show that the saturation magnetic moment value decreases with an increase in temperature and the compound becomes a ferromagnet below the Curie temperature Tc.

Paleomagnetic investigation of the Tarhanian deposits of Cop-Takyl section (Kerch peninsula, Crimea)

<p>With the goal to provide the new magnetostratigraphic investigations of the Miocene marine deposits of the Black Sea Basin the forty-four oriented hand blocks of the Cop-Takyl section (45°N, 36°E, Kerch peninsula, Crimea) were collected during summer 2019 field work. The section is composed mainly of clays, has a total thickness of ~ 53 m and covered the Tarhanian stratigraphic interval. Standard paleomagnetic measurements have been performed to establish a new magnetostratigraphic record for the Cop-Takyl section. The composition of the ferromagnetic fraction was examined using dependences of magnetic susceptibility on temperature and saturation magnetic moment on temperature. These thermo magnetic analyzes showed that the low concentration of magnetite is the main carrier of the natural remanent magnetization NRM. Coercivity of remanence Bcr values, determined from backfield demagnetization measurements, range between ~34 and 91 mT. The structure of the magnetite grains is mainly pseudo-single domain. In order to determine true NRM directions, we studied the anisotropy of magnetic susceptibility. The rock sample possesses a planar anisotropy, which is a characteristic of the normal sedimentary rocks. The alternating field demagnetization of the samples (three duplicates from each level) was used for obtaining NRM vector angle elements. Demagnetization results were analyzed using orthogonal plots and stereographic projections. Polarity components were isolated in most samples between 15-60 mT. The values of the declination D and inclination I of the NRM satisfactory agree for all three duplicates from each level. This allows to average angle elements and construct curves of I and D variations over the thickness of the section. New paleomagnetic data of the Cop-Takyl section will used for assessing the effect of astronomical cyclicity on sedimentation processes. This work was supported by Russian Science Foundation, project № 19-77-10075.</p>

Archeomagnetic studies of fired ceramics from Sakhtysh-I and Sakhtysh -II settlements (Ivanovo Region, Russia)

<p>With the goal to obtain new data of geomagnetic field intensity in the Bronze Age in the Eastern Europe the arheomagnetic study of fired ceramic samples from the settlements Sakhtysh-I and Sakhtysh - II were done. The settlements Sakhtysh-I and Sakhtysh -II are placed in Teikovo district of the Ivanovo region of Russia (56<sup>о</sup>48′ N, 40<sup>о</sup>33′ E). Archeological excavations of ancient ceramics were carried out by the Upper Volga Archeological Expedition of the Institute of Archeology RAS. The studied collection of pottery fragments belongs to three cultures: the Fatyanovo, the Fatyanoid (or the Fatyanivo-like) and the Textile ceramics culture.  The composition of the ferromagnetic fraction presented in the studied archaeological samples have been performed by the complex of standards petromagnetic methods. The thermomagnetic analysis (TMA) in dependence of the saturation magnetic moment on temperature and determination of the Curie points were carry out. Thus based on TMA one can conclude that the main carrier of the magnetisation of the samples is relatively resistant to heat maghemite. The size of grains lies in a pseudo single domain area. The determination of the ancient magnetic field intensity was carried out by modified Thellier method.  Based on the carbon-isotope dating the age of pottery fragments corresponds to the ~ 2000-700 years BC, and we can construct a curve of paleointensity variations of the geomagnetic field from the age.  The data obtained for this period can provide new information about variations of the geomagnetic field intensity during the Bronze Age, which will make it possible to specify the character of changes in geomagnetic field. Earlier for the time interval II millennium BC a certain amount of the geomagnetic field intensity data were obtained in the Russian Plain region. Due to the uncertainty of the dating, these data allowed us to evaluate only the general features of geomagnetic  field intensity variations.  Rapid sharp changes in field intensity occurred with an increase in the average level of the field intensity compared with the level in the previous two millennia. This work was supported by the Russian Foundation for Basic Research, project no. 19-55-18006 and the State task of the Schmidt Institute of Physics of the Earth RAS.</p>

Fe doping-stabilized γ-Ga2O3 thin films with a high room temperature saturation magnetic moment

A thermostable Fe-doped γ-Ga2O3 thin film with a high room temperature saturation magnetic moment of 5.73 μB/Fe has been obtained for the first time.

Structural and Magnetic Studies on Pb4+ Substituted Cobalt Ferrite System

The polycrystalline samples of Co1+xPbxFe2-2xO4 with x = 0.0,0.1,0.2,0.3,0.4, and 0.5 varying in the steps of 0.1 were prepared by using solid state reaction technique. The structural and magnetic properties have been investigated by means of X-ray diffraction, high field magnetization and a. c. susceptibility measurements. The X-ray analysis confirmed the single-phase formation of the samples. The distributions of divalent, trivalent and tetravalent cations among the tetrahedral (A) and octahedral (B) sites have been obtained from the observed and calculated intensity ratios. The X- ray intensity indicates that tetravalent Pb4+ ions occupy both A and B sites replacing iron ions. The added Co2+ ions also occupy at A sites with replacing iron ions for x = 0.0, 0.1 and 0.2 and there after very small amount of Co2+ migrate from A sites to B sites replacing Fe3+ ions for the composition x = 0.3, 0.4, 0.5. The variation of saturation magnetic moment per formula unit at room temperature with Pb4+ content is satisfactorily explained on the basis of Neel’s collinear spin ordering model for all the samples. The Curie temperatures decreases almost linearly with increase of Pb4+ content from x = 0.0 to 0.5.

Effect of Zr Doping on the Magnetic and Phase Transition Properties of VO2 Powder

In this work, V1−xZrxO2 powder (x = 0, 0.01, 0.02, 0.04) was synthesized by two step hydrothermal method. The micro-topography, magnetic and phase transition properties have been investigated using various measurement techniques. All prepared V1−xZrxO2 powder samples exhibit monoclinic structure at room temperature. With the Zr4+ ions doping concentration increased, the shapes of VO2 particles change from spherical to rectangular slice. Besides, the saturation magnetic moment of the samples decrease with the increase of doped Zr4+ ions concentration, while their phase transition temperature increase gradually with Zr ions doping at a rate of around 2 °C/at% on average. We investigated the Zr doping effects on V-V dimers and confirmed the role of V-V dimers in phase transition. We speculate that more V-V dimers form with Zr doping by magnetic measurements, which result in the monoclinic phase of Zr-doped VO2 sample is more stable than rutile phase. Therefore the phase transition temperature is elevated by Zr doping in our experiment. We further consider that the VO2 phase transition should be ascribed to Peierls transition caused by the changing of V-V dimers.

Synthesis, microstructure and magnetic properties of Fe2CoAl nanofibers

In this work, Fe2CoAl Heusler alloy nanofibers were first synthesized via an electrospinning method. It was found that the crystal structure, fiber diameter and magnetic properties of the samples varied with the metal salt concentration in the precursor solution. Magnetic measurement reveals that the obtained Fe2CoAl nanofibers exhibit ferromagnetic with a high Curie temperature and large coercivity. The saturation magnetic moment of the Fe2CoAl nanofibers at 5[Formula: see text]K is estimated to be 4.5–5.1[Formula: see text][Formula: see text]. The Fe2CoAl nanofibers synthesized using the low-cost electrospinning method in our work are magnetically superior and economically feasible for technological applications.

Annealing effects on the magnetic properties of highly-packed vertically-aligned nickel nanotubes

Hysteresis loops showing the decrease of the saturation magnetic moment (left) through a dense array of vertically-aligned Ni nanotubes after their progressive thermal conversion into hybrid ferromagnetic/antiferromagnetic Ni/NiO nanotubes (right).