1,721,557 research outputs found
Incorporation of metal oxide nanocrystals in high temperature YBa2Cu3O7-x superconductors
No full textDigitally printed superconducting coatings and patterns
No full textThe most suitable way to implement superconducting materials in large scale applications is as wires. To overcome the brittle nature of ceramic high-temperature superconductors and to increase the overall performance of the wire, a coated conductor design was developed. In this thesis, we focus on the development of ink-jet processing as a new technique for chemical solution deposition of Y(Gd)Ba2Cu3O7-δ [Y(Gd)BCO] coatings and patterns. For this, cheap and fluorine-free metal salts are used as starting products, which were dissolved in water. The research is mainly focused on the precursor’s chemical stability and printability. The addition of complexing agents is necessary to increase the total metal concentration. Still, an optimisation of the pH value is obligatory for a long shelf life of the precursor solution. A 0.185 mol L-1 YBCO ink with a viscosity of 4.77 mPa s and a surface tension of 67.9 mN m-1 was finally obtained. The printability of the solution is predicted using the ratio: Oh-1= Re/We1/2. With a value of 7.37, the ink’s properties fall within the printing value: 1< Oh-1 <10. After tuning the driving waveform, proper ink-jetting behaviour was visualised using a strobe assisted camera. The optimised deposition parameters resulted in a 350 nm thick YBCO coating, grown on SrTiO3, showing preferential c-axis orientation. This layer exhibits a critical current of 0.67 MA cm-2 at 77 K in self-field. After changing the deposition parameter, high-resolution patterns could be deposited on several substrates. The shape and dimensions of printed YBCO tracks were determined using optical microscopy and noncontact profilometry, showing 100 to 500 nm thick and 40 to 220 µm wide YBCO tracks
Superconducting YBa2Cu3O7-δ nanocomposite films using preformed metal oxide nanocrystals
Full text linkPeople's concern about global warming and the rapid growth of the world population has prompted scientists to develop renewable electrical energy and to find new technologies with a minimum of carbon dioxide emissions. High-temperature superconducting technologies have the potential to transport electricity without resistance. However, the implementation of these high-temperature superconductors in power applications is constrained due to the presence and movement of vortices in the presence of a medium to high magnetic field.
In this research, we focused on the improvement of the superconducting YBa2Cu3O7-δ (YBCO) properties by immobilizing the vortices via the incorporation of preformed metal oxide nanocrystals as artificial pinning centers in the YBCO matrix. The chemical solution deposition approach was introduced to synthesize the high-quality superconducting nanocomposite thin films starting from nano-suspensions for the implementation of the YBCO coated conductors throughout the energy market
Synthesis and microstructural analysis of La2Zr2O7 buffer layers for coated conductors
No full textAfter the discovery of superconductivity, in 1911, a vast amount of superconducting materials has been discovered and produced. Due to its broad range of applications, YBa2Cu3O7-x (YBCO) is one of the most versatile and attractive superconductors.
This thesis has focused on the exploration of superconducting cables using YBCO, by making use of the coated conductor design. A coated conductor consists of a flexible, metallic tape (NiW), coated with a minimum of buffer layers (La2Zr2O7 or CeO2) and a superconducting film (YBCO). This research explores the use of La2Zr2O7 buffer layers, deposited by a novel and environmentally friendly method. The performance of these buffer layers was tested in complete coated conductor setup. Microstructural analysis of the layers by transmission electron microscopic analysis enables a more in-depth understanding of the properties and growth model of the layers
Aqueous chemical solution deposition of La2Zr2O7 and La-, Ce- substituted buffer layers for coated conductors
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Sol-gel chemistry of Y1Ba2Cu3O7-x and CeO2 systems for high-temperature superconducting thin films
No full textMore than twenty years ago in a series of amazing discoveries, it was found that a large family of ceramic cuprate materials exhibited superconductivity at temperatures above the boiling point of liquid nitrogen. Imaginations were energized by the thought of applications for zero-resistance conductors cooled with a relatively inexpensive and readily available cryogen. Compared with other cuprates, YBa2Cu3O7-x (YBCO) seems to be the most promising material because of the current carrying ability in a magnetic field and a high current density self-field. This thesis describes the synthesis using water-based precursors of the superconducting phase YBCO both in bulk and in the capacity of a thin layer. In addition, the preparation of a CeO2 layer via a water-based sol-gel method is also discussed. The thesis has focused mainly on the influence of complexing agents and pH on the precursor and the homogeneity of the precursor gels. The concentration of different possible species in solution was first modeled using the existing numerical algorithms. On the other hand, an experimental verification of the calculated theoretical situation was pursued by potentiometric titration. A second part of the thesis provides insights into the characterization of the gels and the formed oxide phases, such as chemical composition, morphology and preferred orientation. The aqueous precursor formulations, consisting of inexpensive and environmentally-friendly starting materials, studied in this thesis can be a viable alternative to the TriFluoroAcetic acid (TFA) precursors or physical deposition methods nowadays used in fabrication of coated conductors
Ceramic layers of buffers for high Tc superconductors starting from aqueous sol-gel precursors
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