Study of the electrical and thermal conductivity of compounds and solid solutions resulting from the study of the triple system (BaCl2-CuSO4-Na2CO3): دراسة الناقلية الكهربائية والحرارية للمركبات والمحاليل الصلبة الناتجة عن دراسة الجملة الثلاثية (BaCl2-CuSO4-Na2CO3)

In this research, the electrical and thermal conductivity of the compounds BaCl2-CuSO4-Na2CO3 - Ba6Na8C4Cl12O12 - Ba6Cu4S4Cl12O16 - Cu6Na8S6C4O36 and the solid solutions resulting from the interaction of these compounds with each other, using the thermal conductivity measuring device (ITP-M64) and electrical conductivity measurement device (the four paths) were studied. The results are different between superconducting materials and medium conductive materials (semiconductors).

Study on the Relationship between Uniaxial Strain and Critical Transition Temperature of MgB2 Based on First-principles

It has been shown that the critical transition temperature (Tc) of MgB2 superconducting materials decreases with the increase of hydrostatic pressure, but this is a comprehensive Tc change after multiaxial strain, and the influence of strain on Tc is not clearly understood. In this paper, based on the McMillan superconducting calculation formula and the first-principles density functional theory, the Tc change of MgB2 under uniaxial strain and the properties of MgB2 such as energy band, Fermi surface, differential charge density and phonon dispersion spectrum under uniaxial strain are studied, and the relationship between uniaxial strain and these properties is analyzed. The calculated Tc of MgB2 at zero strain is 38.35 K, which is in good agreement with the experimental value of 39 K. When the a-axis strain is 1%, the Tc value can be increased to 49.7 K, and there is a further improvement trend. When the a-axis compression strain is -1%, Tc decreases to 31.52 K. When the c-axis tensioncompression strain is applied, the change of Tc value is small. Further analysis shows that the influence of a-axis strain on the differential charge density, electronic band structure, phonon dispersion and other properties of MgB2 is significantly greater than that of c-axis strain, and the influence of these properties on Tc is discussed. The work in this paper has certain theoretical and guiding significance for the preparation of MgB2 with higher Tc and the study of the effect of uniaxial strain on Tc of superconducting materials.

Method for critical current angular dependencies analysis of superconducting tapes

Various applications of superconducting materials require accounting of the critical current anisotropy relative to magnetic field direction - I c7(θ). However, today there is no sufficiently comprehensive model that takes into account the anisotropy, therefore the angular dependences are usually not analysed, but only described using various mathematical formulas. As a result, the fitting parameters have no physical meaning and it is difficult to correlate the picture with the features of the microstructure. In this paper, we propose a method for analysing the critical current angular dependences based on the anisotropic pinning model. The applicability of this model for conventional superconducting Nb-Ti tapes with one peak in the I c7(θ) dependence is shown. The possibility of extending this model to analyse the angular dependences of HTS materials is discussed.

Special Issue: Advances in Computational Electromagnetics

Recent advances in computational electromagnetics (CEMs) have made the full characterization of complex magnetic materials possible, such as superconducting materials, composite or nanomaterials, rare-earth free permanent magnets, etc [...]

Using Electromagnetic Properties to Identify and Design Superconducting Materials

Superconductors have a wide array of applications, such as medical imaging, supercomputing, and electric power transmission, but superconducting materials only operate at very cold temperatures. Thus, the quest to engineer room temperature superconductors is currently a hot topic of research. To accomplish this mission, it is important to have a complete understanding of the material properties that are being used to create these superconductors. Understanding the atomic and electromagnetic properties of the prospective materials will provide tremendous insight into the best choice for the materials. Therefore, a theoretical model that incorporates electromagnetic field theory and quantum mechanics principles is utilized to explain the electrical and magnetic characteristics of superconductors. This model can be used to describe the electrical resistance response and why it vanishes at the material’s critical temperature. The model can also explain the behavior of magnetic fields and why some superconducting materials completely exclude magnetic fields while other superconductors partially exclude these fields. Thus, this theoretical analysis produces a model that describes the behavior of both type I and type II superconductors. Since there are subtle differences between superconductors and perfect conductors, this model also accounts for this distinction and explains why superconductors behave differently than perfect conductors. Therefore, this theory addresses the major properties associated with superconducting materials and thus will aid researchers in the pursuit of designing room temperature superconductors.

Transmission coefficients of superconducting particles

Objectives. There is no general theory of superconductivity capable of fully describing this phenomenon, which imposes its own difficulties in the search for new superconducting materials, as well as in the study of their properties. In particular, the electrodynamics of a superconducting system is unexplored. With the aim of a possible further description of the electrodynamics of superconductors, the temperature dependences of the energy parameters of a Cooper pair in the potential field of Abrikosov vortex were analyzed.Methods. The basis for the obtained results of the work was the consideration of the transmission coefficient for a superconducting particle in the approximation of the Wentzel– Kramers–Brillouin method, as well as the relationship between the critical temperature and the London penetration depth and the coherence length based on the model of plasmon destruction of the superconducting state.Results. The dependences of the lifetime of a particle in a potential well, penetration depth, frequency of impacts of a particle against a potential barrier, blurring of the energy level, transmission coefficient, and potential and kinetic energy of a particle on temperature were obtained. The characteristic values of these parameters were obtained at absolute zero for various cuprate, organic, and other superconducting materials. The dependences of the critical electric potential on temperature, as well as the London penetration depth, coherence length, and electric potential on the transmission coefficient at different temperatures were obtained. The form of the dependences qualitatively corresponds to the experimental data.Conclusions. The results obtained can be used to construct a general theory of superconductivity, describe the electrodynamics of a superconducting state, and develop new superconductors with higher critical currents.