Increased homogenous clusters in superconducting paths with diffusion of optimum Ni impurities into Bi-2223 crystal

This study deals with variations of electrical and superconducting features of Bi-2223 superconducting materials exposed to Ni impurity diffusion at different annealing temperatures (650 degrees CT850 degrees C) by temperature-dependent resistivity measurements. It is found that the characteristic properties improve with annealing temperature up to 700 degrees C as a result of enhancement in the truly-metallic characteristics, interaction quality, formation of Cooper-pairs and overlapping of Cu-3d and O-2p wave functions. Similarly, the optimum annealing temperature of 700 degrees C diminishes the omnipresent flaws and structural defects. Additionally, we design a strong theory (Percolation) to discuss the role of nickel impurities on fundamental aspects of material science and physical quantities as regards stabilization of superconductivity in the homogeneous regions and formation of superconducting clusters in the paths for the first time. Further, we develop an empirical relationship between the structural problems and transition temperatures to obtain a superconductor exhibiting the highest electrical and superconducting features.https://doi.org/10.1007/s10854-018-9919-

Role of trivalent Bi/Tm partial substitution on active operable slip systems in Bi-2212 crystal structure

This study delves into three main subjects: (I) A strong definition on the variation of fundamental key mechanical design performance and general mechanical characteristic features founded on the formation of active operable slip systems and elimination of structural problems in the Tm substituted Bi-site Bi2.1-xTmxSr2.0Ca1.1Cu2.0Oy (0.00 ? x ? 0.30) ceramic materials; (II) Preference of propagation of cracks and dislocation movements (III) An examination of differentiation in the load-independent microhardness parameters in the saturation limit regions with the Bi/Tm partial replacement. It is found that all the mechanical performance (mechanical strength, stiffness, durability and resistant towards to the failure by fatigue) properties considerably improve with the increment in the Bi/Tm substitution level up to x = 0.07 due to the augmentation in the new active operable slip systems and crystallinity quality of Bi2.1Sr2.0Ca1.1Cu2.0Oy (Bi-2212) system. Accordingly, in case of the optimum Bi/Tm substitution the propagation of dislocation and crack movements is more and more easily controlled in the Bi-2212 ceramic system. However, the excess Tm concentrations in the ceramic system make the stress-induced phase transformation remarkably activate as a consequence of the degradation in the crack orientation and geometry. Hence, any deformation at even lower applied test loads is much more permanent and non-recoverable due to the enhancement of unconstrained dislocation motions and especially entanglement of cracks and dislocations. This fact is also confirmed from the reduction of typical indentation size effect (ISE) behavior in the event of excess Tm concentration. To conclude, the optimum Bi/Tm partial replacement in the Bi-2212 crystal structure is successful to improve the economic lives of Bi-2212 inorganic ceramics in the new, novel, innovative, feasible and potential design areas for the universe economy. © 2020 Elsevier Lt

Effect of vanadium addition on fundamental electrical quantities of Bi-2223 crystal structure and semi-empirical model on structural disorders-defects

Ulgen, Asaf Tolga/0000-0002-7112-5607; Erdem, Umit/0000-0002-0480-8176WOS:000548260800001The primary contribution of the present study is to determine the effect of vanadium addition on the fundamental aspects of characteristic crystalline and electrical quantities for the Bi1.8Sr2.0Ca2.2Cu3.0VxOy (0.00 <= x <= 0.30) crystal system using the powder X-ray diffraction (XRD), temperature-dependent electrical resistivities and semi-empirical approaches founded on the structural disorders-defects. The de electrical resistivity results show that every electrical quantity is found to degrade regularly with the increment in the addition level as a consequence of the induced permanent structural disorders-defects, intergranular grain boundary coupling interaction problems and non-superconducting barrier regions in the bulk Bi-2223 superconducting system. The vanadium addition brings also about the characteristic transition from over-doped state to under-doped state due to the suppression in the overlapping of Cu-3d and O-2p wave functions. The XRD results indicate that the vanadium addition leads to shift the characteristic peaks towards the larger/lower angles in terms of the peak positions in the reference data, enlarge the diffraction peak widths (line broadening of X-ray diffraction), appear or disappear new peaks, increase/decrease the average grain size, lattice cell parameters and superconducting phase fractions founded on the diffraction intensities. Based on the evidences, the presence of vanadium particles in the bulk Bi-2223 superconducting phase damages crucially the fundamental characteristic features. Moreover, it is found that characteristic two-stage (bulk genuine, T-c(mid) and coherence, T-co) transition temperatures decrease systematically with the addition level. On this basis, the presence of vanadium impurity in the system leads to degrade the stabilization of superconductivity in the small homogeneous clusters in the paths and especially effective electron-phonon coupling (bipolaron in the polarizable lattices) probabilities due to the reduction of hole trap energy per Cu ions in the valence band of system. Additionally, the results display that the vanadium particles affect negatively on both the dirty limit characteristic feature and gap coefficient of Bi-2223 ceramic compound as a result of the decrement in the minimum required energy for breaking up the cooper-pairs in the system. At the same time, the electrical resistivity curves enable us to develop a sensitive semi-empirical approach to find the possible highest onset critical transition temperature for the ideal crystallinity. The model founded on the crystallinity quality displays that the possible highest onset transition temperature is about 116.037 K +/- 1.25587 K with R-adj(2) = 0.948

Effect of homovalent Bi/Ga substitution on propagations of flaws, dislocations and crack in Bi-2212 superconducting ceramics: Evaluation of new operable slip systems with substitution

This study defines a strong methodology between the mechanical performance behaviors and formation possible operable slip systems in the crystal structure of Bi-2212 superconducting phase with trivalent Bi/G substitution with the aid of Vickers hardness tests exerted at various indentation load intervals 0.245 N-2.940 N. It is found that the mechanical performance behaviors improve regularly with the increment in the trivalent Bi Ga partial substitution level up to the value of x = 0.05 due to the formation of new operable slip system. Namely, the optimum gallium (Ga) impurities serve as the strain fields and associated forces for the interaction of dislocations within the different orientations with each other to impose the surface residual compressive stresses orienting favorably the superconducting grains. Thus, the propagation of dislocations, flaws and cracks divert in the crystal structure. On this basis, the presence of optimum Ga impurity in the Bi-2212 crystal syster strengthens the mechanical strength, critical stress, resistance to the plastic deformation, stiffness and durabilit nature. Moreover, the experimental results advance in-depth understanding of fundamental links between th porosity and Young's moduli of elasticity founded on the impurity level and applied test loads. It is observed that in case of the optimum level of x = 0.05 the propagation of flaws, dislocations and cracks proceed along the transgranular regions instead of the intergranular regions as a consequence of improvement in the durabl tetragonal phase. On the other hand, the excess Ga content level in the polycrystalline Bi-2212 system results i the augmentation in the stress raisers, crack surface energy and crack-initiating flaws, activating the stress-induced phase transformation

A novel research on the subject of the load-independent microhardness performances of Sr/Ti partial displacement in Bi-2212 ceramics

Ulgen, Asaf Tolga/0000-0002-7112-5607WOS:000587111900001This work is interested in the critical changes in the load-independent microhardness performance parameters with the partial substitution of Sr2+ inclusions for the Ti4+ impurities in the Bi-2212 inorganic solids with the help of the theoretical approximations as regards Meyer's law (ML), proportional sample resistance (PSR), modified proportional sample resistance (MPSR), elastic/plastic deformation (EPD), Hays-Kendall (HK) and indentation-induced cracking (IIC) models found on the experimental microhardness tests applied to a variety of test loads between 0.245 and 2.940 N for the first time. Moreover, Ti-substituted Bi-2212 bulk ceramics (Bi2.1Sr2.0-xTixCa1.1Cu2.0Oy) are prepared within mole-to-mole ratios of x = 0.000, 0.010, 0.030, 0.050, 0.070, 0.100 by the standard solid-state reaction method in the atmospheric pressure conditions. It is provided that Ti partial substitution in the superconducting system descends unsmilingly the mechanical durability, stability, strength, toughness, critical stress, stiffness and flexural strengths of Bi-2212 superconducting solids studied owing to the increment of crystal structural problems. Moreover, it is obtained that the degradation in the crystal structural leads to diminish the typical ISE characteristic of Bi-2212 superconducting ceramic compounds. At the same time, the results show that all the models (especially IIC approach) can serve as the suitable descriptors for the determination of the variation in the load-independent mechanical performances of the Bi-2212 superconducting materials

Evaluation of key mechanical design properties and mechanical characteristic features of advanced Bi-2212 ceramic materials with homovalent Bi/Ga partial replacement: Combination of experimental and theoretical approaches

This study models the variations in the key mechanical design properties and mechanical characteristic features of Ga substituted Bi-site Bi-2212 ceramics prepared within the different molar ratios of x = 0.000, 0.005, 0.010, 0.030, 0.050, 0.100 and 0.300 with the assistant of available theoretical approaches; namely, Meyer's law, proportional sample resistance, elastic/plastic deformation, modified proportional sample resistance model, Hays Kendall and indentation-induced cracking methods for the first time. The mechanical modeling parameters are gathered from the microhardness (Vickers) experimental tests performed at various applied loads interval 0.245 N-2.940 N. The results provide that the key mechanical design features improve systematically with the augmentation of trivalent Bi/Ga partial replacement level up to x = 0.05 due to the rapid decrement in the main structural problems; namely, the grain orientations, lattice strains, distortions, dislocations, grain boundary interaction/coupling problems, crack-initiating and crack-producing omnipresent flaws in the advanced Bi-2212 ceramic system. Accordingly, the optimum Ga inclusions strengthens the mechanical durability towards the applied stress due to the increased stabilization in the durable tetragonal phase. After the critical substitution amount of x = 0.05, the mechanism turns reversely, and the general mechanical characteristic features including the stiffness, mechanical durability and strength degrade remarkably. Additionally, the mechanical modeling results demonstrate that the Bi/Ga impurity leads to vary positively the quality of standard indentation size effect (ISE) feature until x = 0.05, beyond which the excess Ga additives damage seriously ISE feature of Bi-2212 inorganic compounds. Besides, the indentation-induced cracking (IIC) model is noticed as the best method to describe the true microhardness parameters of Bi/Ga substituted Bi-2212 compounds for the mechanical characterization.https://doi.org/10.1016/j.ceramint.2019.07.09

Important defeats on pinning of 2D pancake vortices in highly anisotropic Bi-2212 superconducting matrix with homovalent Bi/La substitution

Yildirim, Gurcan/0000-0002-5177-3703; saritekin, namik kemal/0000-0002-0759-0598WOS: 000350388800019This comprehensive study aims to investigate the change of the flux pinning mechanism, electrical and superconducting properties of the inorganic solid Bi-2212 materials with the La inclusions inserted in the crystal structure by means of magnetotransport measurements exerted in the applied magnetic field range of 0-7 T. Crucial characteristics as regards critical transition temperatures (T-c(onset) and T-c(offset)), room temperature resistivities (rho(300K)), residual resistivities (rho(0)), residual resistivity ratios (RRR), irreversibility fields (mu H-0(irr)), upper critical fields (mu H-0(c2)), thermodynamic critical fields (mu H-0(c)), activation energies (U-0), penetration depths (lambda) and coherence lengths (xi) are evaluated from the experimental magnetoresistivity curves and available theoretical approaches. All the properties obtained above confirm the considerable degradation in the pinning of 2D pancake vortices with the increment of the La individuals randomly distributed in the Bi-2212 superconducting system. Thus, the improved recoupling linelike nature among the consecutively stacked layers leads to decoupling of the adjacent layers and suppression of the interlayer Josephson coupling length as a result of the enhancement in the thermal fluctuations of flattened pancake vortices. The long and short of it is that the La impurities undermine the elasticity of the vortex lattice. For example, the T-c(offset) and T-c(onset) values are found to be about 84.5 K and 85.7 K for the best (pure) sample while the material exposed to the La content level of x = 0.2 obtains the values of 82.2 K and 15.1 K, respectively at zero applied magnetic field. In the case of the applied magnetic field of 7 T, the T-c(offset) value reduces considerably towards the lower temperature values of 72.6 K for the former compound. However, the values belonging to the worst sample (La4) cannot be determined at higher external magnetic field value such as 1 T due to the hybridization of La-3/states with the Cu3d-O2p states in the Cu-O-2 layers (dissipation). This is attributed to the existence of the pair-breaking mechanism in Bi-site La substituted Bi-2212 systems. Moreover, the flux pinning energy values calculated from thermally activated flux flow (TAFF) model decrease dramatically with the enhancement of both the La content level and external magnetic fields. Numerically, the activation energy value is calculated to be about 5173 K (1077 K) for the pure sample at the field value of 0 T (7 T) whereas the values pertaining to the compound substituted by the La concentration level of x = 0.15 are found to be in a range of 1196-281 K. The lack of the experimental evidences does not enable us to find the energy values belonging to the La4 sample at higher applied field. As for the critical field parameters (mu H-0(c1), mu H-0(c), mu H-0(irr), mu H-0(c2) and mu H-0(c3)) and the extracted values (lambda, xi and kappa), the changes in the parameters given also verify the degradation of the flux pinning ability (random distribution of the artificial pinning centers) with the La concentration as a result of the Cooper pair-breaking mechanism. To sum up, the La impurities are unfavorable for the potential applications of these materials in the commercial sector at high temperatures and magnetic fields. (C) 2015 Elsevier B.V. All rights reserved.Abant Izzet Baysal University Scientific Research Project Coordination UnitAbant Izzet Baysal University [2013.09.03.655]This study is partially supported by Abant Izzet Baysal University Scientific Research Project Coordination Unit (Project No: 2013.09.03.655)

A detailed research for determination of Bi/Ga partial substitution effect in Bi-2212 superconducting matrix on crucial characteristic features

This multidisciplinary study paves way to investigate the crucial of fundamental characteristic properties including the bulk density, electrical, superconducting, flux pinning mechanism, crystal structure quality and strength quality of interaction between the superconducting grains in the Bi(2.1)Sr(2.0)Ca(1.1)Cu(2.0)Oy (Bi-2212) superconducting materials with the partial replacement of gallium foreign impurity by bismuth nanoparticles in the crystal structure. Characterizations of polycrystalline ceramic materials prepared by standard ceramic route in the atmospheric air are performed by means of conventional experimental measurement methods such as powder X-ray diffraction, Archimedes water displacement, dc electrical resistivity versus temperature and critical current density examinations. All the bulk Bi-site Ga partial replaced materials exhibit the Bi-2212 superconducting phase within the different fraction levels (%73.1 -94.8), moderate self-field critical current densities 54-96 A/cm(2) and wide-ranging offset and onset critical transition temperature range of 45.65 K-84.52 K and 70.06 K-85.00 K. As for the experimental findings of bulk density and related degrees of granularity (porosity) parameters, the bulk density parameter is found to be between 5.76 g/cm(3) and 6.12 g/cm(3) when the corresponding residual porosity value is also obtained to be in a range of 8.57 % -2.86%. Moreover, the mobile hole carrier concentrations in the short-range-ordered antiferromagnetic Cu-O-2 layers are found to be in the range from 0.085 until 0.152. Additionally, the role of Ga/Bi partial substitution in the crystal lattice on the normal state resistivity, residual resistivity, residual resistivity ratio, vibrational mode intensities, texturing, superconducting volume fractions, mobile hole carrier concentrations, average crystallite sizes, Lotgering indices and cell parameters are discussed in details. All the experimental results and theoretical approaches show that the characteristic properties tend to improve regularly with the increment in the Ga foreign impurity level until x = 0.05 due to the increment in the crystal structure quality and interaction between the superconducting grains. After the critical Ga/Bi substitution level of x = 0.05, every feature degrades considerably. (C) 2018 Elsevier B.V. All rights reserved

Improvement of Mechanical Characteristics and Performances with Ni Diffusion Mechanism Throughout Bi-2223 Superconducting Matrix

This study is interested in the role of diffusion annealing temperature (650-850 degrees C) on the mechanical characteristics and performance of pure and Ni diffused Bi-2223 superconducting materials by means of standard compression tests and Vickers hardness measurements at performed different applied loads in the range of 0.245-2.940N and theoretical calculations. Based on the experimental findings, the mechanical performances improve with increasing annealing temperature up to 700 degrees C beyond which they degrade drastically due to the increased artificial disorders, cracks and irregular grain orientation distribution. In other words, the penetration of excess Ni inclusions accelerates both the dislocation movement and especially the cracks and voids propagation as a result of the decrement in the Griffith critical crack length. Further, it is to be mentioned here that all the sample exhibit typical indentation size effect (ISE) behavior. In this respect, both the plastic (irreversible) and elastic (reversible) deformations have dominant role on the superconducting structures as a result of the enhancement in the elastic recovery. At the same time elastic modulus, yield strength and fracture toughness parameters are theoretically extracted from the microhardness values. Moreover, the elastic modulus parameters are compared with the experimental values. It is found that the differentiation between the comparison results enhances hastily with the increment in the applied indentation test loads due to the existence of the increased permanent disorders, lattice defects and strains in the stacked layers. Namely, the error level increases away from the actual crystal structure. Additionally, the microhardness values are theoretically analyzed for the change of the mechanical behaviors with the aid of Meyer's law, elastic/plastic deformation and Hays-Kendall approaches for the first time