Papers by Keyword: Magnetic Susceptibility

Abstract: Chinese loess-paleosol sequence has archived the most detailed terrestrial records of past climatic and environmental changes. In this study, we concentrate on Zhuli loess section in northern Shandong, by sedimentary and magnetic and optically stimulated luminescence (OSL) methods. Based on the OSL ages, the basal age of the Zhuli section is 60ka extrapolated by sedimentation rates. Grain-size curves indicate that environment-sensitive size fractions of Zhuli section are 39.81-44.67μm and 79.43-89.12μm respectively, by analyzing grain-size class vs. standard deviation values method. The low-frequency magnetic susceptibility has a good correlation with the high-frequency magnetic susceptibility, and the grain size has a good correlation with the magnetic susceptibility.

Abstract: PbFeBO₄ and PbMnBO₄ single crystals were synthesized. The X-ray, magnetic, dielectric, Mössbauer, and resonance investigations of the crystals were fulfilled. It is established that single-crystal PbFeBO₄ is an antiferromagnet with a Néel temperature T_N =114 K, while PbMnBO₄ is a ferromagnet with a Curie temperature T_C = 31 K. Both single-crystal compounds have a strong anisotropy of the magnetic and dielectric properties.

Abstract: The effect of cobalt deficiency in a single crystal of double layered cobaltite GdBaCo_1.86O_5.32 on the magnetic properties was investigated. We have found that in the region 210 - 400 K the sample has the ferrimagnetic state with the Neel temperature (T_N ~ 400 K) which is above the Curie temperature (T_C ~ 262 K). In the paramagnetic region T = 410 - 650 K the effective magnetic moment is μ_eff = 8.78 μ_B, that points out the intermediate spin state (IS) of Co³⁺ ions.

Abstract: The structure and magnetic properties of multi-walled carbon nanotubes produced by catalytic pyrolysis of methane have been investigated by means of mutually complementary physical methods. The average sizes and number of carbon layers forming nanotubes, smearing of the density of states near the Fermi level, degeneracy temperature of gas of extrinsic current carriers, concentrations of localized spins and extrinsic two-dimensional current carriers have been determined. The conclusion has been drawn that ferromagnetic nanoparticles are present in the inner regions of nanotubes, including their tubular cavities. The difference in electronic structure near the Fermi level for carbon nanotubes and ordered graphite has been revealed. The possible reason is that the electronic states near zigzag-type sites of ends as well as edges of linear structural defects in nanotubes make greater contribution to the spectrum than that from similar sites of graphite.

Abstract: The HTS-42 (High Temperature Solder) properties in the liquid state have been studied. The optimal operating conditions for the solder melt time-temperature treatment, used for producing amorphous ribbons having the specified service properties, are recommended based on the analysis of the anomalies properties and temperature polytherms shape. The subsequent thermal treatment of soldered joints is not shown appropriate for soldering homogeneous melts not hardened by age (precipitation) hardening. The strength of such products can be improved by increasing the contact joint area. The HTS-42 solder amorphous ribbons enable, as compared to the powder semi-finished product, reducing its consumption by 2-3 times, improving the carrying capacity of soldered constructions by 20-40 %, which makes the soldering practice resource saving and significantly improves the product reliability.

Abstract: Magnetic Susceptibility values of garden soil, agriculture ecosystem park soil and soil in urban-rural ecological transition zone in Xuchang city are smaller than 100×10^-8 m³/kg, and the frequency magnetic susceptibility values are more than 3%, such is different from soils influenced by industrial. That above three kinds of soils with slight pollution are effected by different land uses show soil magnetic Susceptibility is a powerful indicator of soil pollution. The result of soil magnetic Susceptibility is higher shows that he pollution threats exist in agriculture ecosystem parks in villages and towns around the city.

Abstract: Along with the fast development of high-technology fields in China, especially in aviation and aerospace, in order to meet the fast and accurate detection requirements of various magnetic material properties, to solve artificial measurement error and low efficiency on the current manual measuring way, a kind of automatic magnetic balance system was developed. The mechanism design, measurement & control system design and the main technical indicators were also described. The application results show that the automatic magnetic balance system can work stable and reliable, and the test capacity of the system is effectively expanded because of higher precision, higher measuring efficiency and more convenient operation, so the system can satisfy the testing requirements in the process such as scientific research, manufacture, teaching and etc.

Abstract: Magnetic susceptibility characteristics as well as the relationships between magnetic susceptibility and As, Hg, Cu, Pb, Cd, Cr were investigated in the typical contaminated areas of southern Jiangsu Province.It was found that the correlations between magnetic susceptibility and Cu, Pb were relatively significant, while the correlations between magnetic susceptibility and Cd, As were weak. Heavy metals in soils from industrial wastewater discharge were associated with the magnetic susceptibility, which showed better correlation than other pollution sources.The primary component analysis showed heavy metals in soils from Nanjiao area were mainly the dust from metallic factory , Source of heavy metals in the soils of Ehu area showed the close relationship with the industrial wastewater source in this area.Characteristics of heavy metals in Dingshu area were associated with the source of the mixed wastewater.It is apparent that the different sources will lead to the changes of the correlation between heavy metals and magnetic susceptibility. Generally,the relationship between heavy metal and susceptibility is good in the soils irrigated with industrial wastewater, and metals from the mixed wastewater show a relatively poor correlation with the magnetic susceptibility.

Abstract: The changes of magnetic property of several iron bearing sulfide minerals after strong beam current electron irradiation are examined. Data shows that the magnetic susceptibility of arsenopyrite and chalcopyrite increases markedly compared to that of pyrite and marmatite. The magnetic susceptibility of arsenopyrite exceeds the lowest ferromagnetic limit 3000 cm³/g, while the susceptibility changes of other minerals are relatively slow. The irradiation dose is the dominate parameter determining the magnetic susceptibility change. Electron beam irradiation might be a potential method to enlarge the magnetic property distinction between the minerals for their magnetic separation.

Abstract: Polycrystalline sample of the reduced barium titanate Ba₄Ti₁₂O₂₇ was prepared by solid state reaction in Ar atmosphere. The magnetic susceptibility was nearly temperature independent in the range of 75-300 K, suggesting the Van Vleck Paramagnetism. The temperature dependence of the electric conductivity does not obey any Arrhenius type behavior.