Papers by Keyword: Magnetic Susceptibility

Abstract: We have succeeded in synthesizing new arsenic-based filled skutterudite compounds CaFe₄As₁₂ and BaOs₄As₁₂ under high pressure. These compounds have lattice constants of 8.3288 and 8.5809 Å, respectively. The magnetic properties of CaFe₄As₁₂ and BaOs₄As₁₂ have been studied by means of electrical resistivity, magnetic susceptibility and magnetization measurements. The electrical resistivity and magnetic measurements indicate that CaFe₄As₁₂ is a nearly ferromagnetic metal with spin fluctuations of Fe 3d electrons and BaOs₄As₁₂ is a new superconductor with a transition temperature around 3 K.

Abstract: Percolation networks of electrically connected nanographenes are the promising structures for solving the problem of the transfer of their peculiar quantum properties to the macroscopic level. In this work we report the results of investigations, conducted with using a set of complementary physical methods, on the origin, structural motifs and properties of such networks revealed in thermally reduced graphene oxide films. The presence of zero modes, which may be π-electronic states stabilized at the zigzag edges of network elements, has been established.

Abstract: Studies of the properties steels and alloys in the liquid and solidity conditions bear witness that the technical peculiarities of the receipt liquid metal in particular overheating have influence on the its properties and structure. The time-temperature treatment of the liquid metal influence on the structure of the liquid metal. The structure of the liquid metal influence on the character hardening and properties of the solidity samples in the one's turn. It should be noted the fact that place the just regularity take place: than extent of the melt equilibrium before crystallization is higher the solid metal distinguish oneself the better figures of the quality.

Abstract: The athermal ω phase transformation, magnetic susceptibility and deformation behavior of Zr-xNb alloys (x = 10 and 14) for use in medical devices subjected to magnetic resonance imaging (MRI) were investigated using electrical resistivity measurements, transmission electron microscopy observations and compression tests. The alloy with x = 10 exhibited a positive temperature coefficient in the electrical resistivity curve and the presence of an athermal ω phase at room temperature. On the other hand, the alloy with x = 14 showed an anomalous negative temperature coefficient (NTC) in the resistivity curve. Similar NTCs also appear in β-Ti alloys, which is interpreted as the growth of an athermal ω phase and the appearance of lattice modulation. The ω phase and diffuse satellites, which are possibly related to lattice modulation, were confirmed in the Zr-14Nb alloy at room temperature. The volume fraction of the athermal ω phase and the appearance of lattice modulation are related to the operating deformation mode and Young’s modulus. Thus, controlling the ω phase transformation in Zr-Nb alloys is key to developing medical devices that can be used in MRI.

Abstract: The data on atomic and electronic structure and some magnetic properties of graphite domains in activated carbon fibers (ACF) are presented. It has been established that graphite domains have nanometer sizes in all three dimensions, and consist of about three turbostratically stacked nanographenes. Such multilayer nanographene clusters (nanographites) are structural blocks of ACF and they are separated from each other by the micropores and/or sp³-amorphous carbon phase. From the data of magnetic methods of investigations, it follows that the density of states at the Fermi energy in nanographites is significantly larger than the value of that parameter in macroscopic graphite, which testifies the existence of edge π-electron states in them.

Abstract: The magnetic susceptibility dependence on temperature near phase transition point was investigated by theoretical analysis. It is shown that with decreasing of the film thickness the magnetic susceptibility shape curve becomes more rounded finite-size function, centered about the lowered temperature Tc (L). The obtained results are in good agreement with experimental data.

Abstract: Temperature dependence of the low-frequency complex magnetic susceptibility of magnetic colloid with paraffin as a dispersion medium has been studied. When interpreting the obtained results, the specific features of the magnetic moment relaxation of single-domain particles and the possibility of changing of relaxation mechanism from Neel to Brownian have been considered.

Abstract: The temperature dependences of the magnetic susceptibility χ (T) of diluted magnetic semiconductor HgSe:Ni (1·10¹⁸ < N_Ni < 1·10¹⁹) cm^-3 were investigated. It was found that paramagnetic part of the susceptibility which is wholly due to the effect of the impurities in the range of temperature from 1.8 to 200 K is described by the Curie-Weiss law. The analysis of the concentration dependence of the Curie constant C(N_Ni) based on the model of the hybridized electronic states was carried out. The application of this model allowed us to determine the microscopic parameters of the electronic structure of these crystals (the effective spin of the hybridized electronic states at the nickel impurity S_i and the resonance concentration of donor electrons n_0d).

Abstract: The experimental evidence for the existence of chain paramagnetic Curie-type contribution to the temperature dependence of the normal (non-superconducting) state magnetic susceptibility χ (T) was obtained for pure high-Tc superconductors (HTSC) YBa₂Cu₃O_6+δ series with different oxygen contents (0.6 < δ ≤ 1). It was shown that this contribution became clearly evident on curves χ (T) only at the temperature T < 150 K. It increases with the amount of oxygen vacancies increase in Cu1–O4 chains, and also depends on the way of the oxygen vacancies ordering.

Abstract: Magnetic susceptibility is the most commonly used soil magnetic parameters, reflecting the degree of magnetization substance. The investigation of two typical soil sections in Pingyi County, Shandong Province shows that there are some differences on magnetic susceptibility between the cinnamon soil profile and the brown soil profile. The results indicate that: (1) Significant difference of magnetic properties is existed among the cinnamon soil profile and the brown soil profile. The mean χ_lf value of the samples from the cinnamon soil profile is 82.80×10-8m3/kg, distinctly lower than those from the brown soil profile, which have a mean value of 616.72×10-8 m3/kg; (2) This indicates a low proportion of SP in samples from the brown soil profile and a high proportion of SP in samples from the cinnamon soil profile; (3) Magnetic susceptibility features is a new method which can be used for soil preliminary classification.