EVALUATION OF EFFECTIVE OPERATORS FOR CONFIGURATION INTERACTION

Les corrections aux intégrales de Slater calculées par la méthode Hartree-Fock, dues aux interactions de configuration électrostatiques, ont été calculées pour la configuration 4 f2 du Pr IV, en utilisant la théorie des perturbations et des méthodes graphiques. Le paramètre α de Trees, ainsi que les paramètres β et γ ont été calculés également. Au second ordre, les interactions avec 27 configurations liées et 8 excitations monoélectroniques vers le continuum donnent α = - 4,24, β = 103,85, γ = - 200,30 Ceci est à comparer avec les valeurs empiriques : F2 = 72 549, F4 = 53 874, F6 = 35 973, α = 24, β = -586 et γ = 728.Corrections to the Hartree-Fock Slater integrals due to electrostatic configuration interaction are calculated for the 4 f2 configuration of Pr IV using perturbation theory and graphical methods. The Trees parameter α and the additional parameters β and γ are also calculated. To second order the interaction with 27 bound configurations and 8 single particle excitations to the continuum give F2 = 88 963,14, F4 = 61 000.08, F6 = 33 353,80. This may be compared with empirical values F2 = 72 549, F4 = 53 874, F6 = 35 973, α = 24, β = 586, γ = 728

Dispersion of magnetic susceptibility in a suspension of flexible ferromagnetic rods

The properties of suspensions of magnetosomes extracted from magnetotactic bacteria are investigated. By using dynamic light scattering and measuring the dispersion of magnetic susceptibility it is shown that sonicated samples with broken magnetosome chains have qualitatively different behavior in comparison with native samples. This is explained by the presence of flexible chains of magnetosomes in non-sonicated samples which have the qualitative features of magnetic susceptibility predicted by the model of flexible magnetic rods

Electrical and dielectrical properties of composites based on (Ag1–xCux)7GeS5I mixed crystals

Polymer composites were prepared from (Ag 1–x Cu x ) 7 GeS 5 I mixed crystals grown using Bridgman–Stockbarger method. The impedance measurements were performed at room temperature in the frequency range 10 –3 –2·10 6 Hz. The frequency dependences of electrical conductivity and dielectric permittivity for composites based on (Ag 1–x Cu x ) 7 GeS 5 I mixed crystals were obtained. The Nyquist plots for (Ag 1–x Cu x ) 7 GeS 5 I-based composite has been analyzed. The influence of cation Ag→Cu substitution on electrical conductivity of composites based on (Ag 1–x Cu x ) 7 GeS 5 I mixed crystals has been studied

Small Angle X-ray Scattering Study of Magnetic Nanofluid Exposed to an Electric Field

We report on the investigation of a transformer oil-based magnetic nanofluid exposed to an electric field by means of synchrotron small angle X-ray scattering. Two types of small angle X-ray scattering experiments were carried out. In the first one, the electric field up to 6 kV / cm was generated in the nanofluid between two immersed electrodes. The other experiment focused on the nanofluid in an external electric field up to 10 kV / cm, when the electrodes were not in a direct electrical contact with the nanofluid. In the available range (0.02–4.5 nm$^{−1}$) of scattering vector $q$, the non-contact mode has no effect on the scattering intensity. The contact mode yielded noticeable low-$q$ intensity variations. In comparison to small angle neutron scattering, the small angle X-rayscattering study did not prove the proportional increase in the low $q$ scattering intensity with increasing electric field, but rather stochastic variations. The observed intensity variations reflect the local structural nanofluid changes caused by the induced electrohydrodynamics. The electrical conductivity and relaxation processes are pointed out as favorable conditions for electrohydrodynamics in the magnetic nanofluid

Magnetic Hysteresis Loops Revisited: Step Closer to Understand the Role of Exterior Angles

The characterization of nanocomposite samples which contain Cu, Fe-species, prepared by the sol-gel method, was established by Nikolić et al., in a previous article (Nikolić et al. in Journal of Solid State Physics 513:1, 2021). In this study, the magnetic behavior of nanocomposite samples was examined. The basic parameters of the room- and low-temperature magnetic hysteresis loops are discussed. To better describe the shape of magnetic hysteresis loop, the authors proposed to consider additional parameters - measures of the exterior angles of the hysteresis curve. Behavior of hysteresis parameters and exterior angles, caused by annealing treatment, was investigated by measuring hysteresis loops at two measured temperatures: 298K, and 5K. Correlation between changes in the behavior of hysteresis parameters and exterior angles was discussed. An attempt has been made to attribute physical meaning to chosen measured angles, which would allow a better understanding of the magnetic hysteresis curve. © 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature