[en] This article details the solid-state synthesis of high-temperature superconducting YBa₂Cu₃O_7−x. Tests were carried out on samples formed at different pressures (200, 400, 600 and 800 MPa) before being annealed under pure oxygen. The X-ray diffraction method showed that, regardless of the forming pressure, the samples contain about 97 wt.% of Y-123 phase. SEM images showed a polycrystalline structure of samples of similar grain size and number of pores (intergranular spaces). The values of critical temperatures (T_c0), determined from magnetoresistance measurements, are about 91.5 K for all samples, and the T_c0 temperatures do not depend on sample-forming pressure. Magnetoresistance measurements have shown that samples formed with higher pressures exhibit smaller changes in T_c0 and superconducting transition width ΔT due to the influence of the H_DC magnetic field, than the samples formed with lower pressures. Values of specific resistance determined by the use of van der Pauw method at 300 K is about 2 mΩcm for all samples. The critical temperatures (T cintra) of grains and critical current densities at 77 K were determined from AC magnetic susceptibility measurements, and they are about 91.6 K and 400 A cm⁻², respectively.

[en] The article deals with issues related to light clay and straw bale in modern housing. It presents the characteristics of clay and straw, as building materials. Attention is paid to the possibility of using these raw materials for building walls in single-family houses. In addition, the paper presents a thermal analysis for this type of walls and the resulting conclusions, which allow for the treatment of straw bale and light clay as a viable alternative to commonly used technologies for erecting buildings. According to the PN-EN ISO 6946: 2008 standard, thermal resistance and heat transfer coefficient were calculated for selected vertical partitions. Other natural building technologies have been omitted. (paper)

[en] The aim of the research is to create new high-temperature superconductors (HTS) NdBa₂Cu₃O_7-x, SmBa₂Cu₃O_7-x, EuBa₂Cu₃O_7-x, and Nd_1/3Sm_1/3Eu_1/3Ba₂Cu₃O_7-x based on light rare earth (LRE) metals. The superconducting materials are investigated for microstructural and physicochemical properties. The paper describes the preparation process of substrate powders and the granulation results of the raw material mixtures before the first calcination, as well as after the first and the second calcination. The granulation analysis of the raw materials are performed using a low-angle laser light scattering (LALLS) method. Qualitative and quantitative phase analysis of the superconducting materials after the first and the second calcination and after annealing in oxygen atmosphere have been performed by X-Ray diffraction (XRD) technique. A detailed structural investigations mainly shows the orthorhombic phase with small amounts of BaCuO₂ and CuO compounds detected in all samples. A microstructural analysis of materials are carried out by using Raman spectroscopy and scanning electron microscopy (SEM), respectively. The magnetic properties of the superconducting materials are characterized by AC magnetic susceptibility as a function of temperature. The critical current densities at liquid nitrogen temperatures were also measured. (copyright 2018 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)