Infiltration-reaction process for fabricating YBa2Cu3O7−δ superconductor

Optimizing the wavelength ($\gamma$) of the Halbach array permanent magnet guideway (PMG) in superconducting maglev systems can improve levitation performance without consuming additional materials. The value of $\gamma$ impacts the external field intensity $\boldsymbol{H}_{\mathrm{e}}$ and gradient $\nabla \boldsymbol{H}_{\mathrm{e}}$ generated by the PMG. The total amount of magnetic field energy is fixed, and the $\gamma$ essentially regulates the distribution of this energy. Reducing $\gamma$ concentrates more magnetic field on the PMG surface, resulting in larger force and stiffness when the levitation height approaches zero. To validate this conclusion, experiments, approximate calculations and numerical simulations have been in all employed. However, excessive reducing $\gamma$ at higher heights is not ideal as it tends to distribute most of the field energy below the desired height. The approximate method in this paper indicates that the levitation force is positively correlated with $(\frac{\boldsymbol{H}_{\mathrm{e}}^{2}}{2H_{\mathrm{p}}}-\boldsymbol{H}_{\mathrm{e}})\nabla \boldsymbol{H}_{\mathrm{e}}$. Therefore, the objective is to determine the optimal $\gamma$ that maximizes this index. Optimal values for $\gamma$ at different heights have been identified, offering guidance for PMG design. Additionally, applying these findings to two existing PMGs results in 18\% and 8.6\% augmentation in levitation force respectively. Furthermore, a fully optimized PMG design has the potential to achieve a levitation force of nearly 10 kN/m, while keeping the cross-sectional areas of the PMG and SC restricted to 4450 mm$^2$ and 2500 mm$^2$, respectively.

Section: Effect Of Wavelength At Near Zero Heightmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Enhancing levitation force of superconductors through wavelength optimization in Halbach permanent magnet arrays

Liu,

Si,

et al. 2024

“…However, there is another drawback of the MTMG approach: the uncontrolled shrinkage of the original pellet [5]. Due to these problems, another approach was introduced as early as 1991 [6][7][8][9][10]; the so-called infiltration growth (IG) technique. Here, a Y-211 precursor pellet is formed which is then used as a base material together with a liquid source and a seed crystal.…”

Section: Introductionmentioning

confidence: 99%

Secondary phase particles in bulk, infiltration-growth processed YBCO investigated by transmission Kikuchi diffraction and TEM

Koblischka-Veneva¹,

Koblischka²,

Schmauch³

et al. 2020

We present results of the first application of the transmission Kikuchi diffraction (TKD) technique to bulk, infiltration growth (IG)-processed YBa 2 Cu 3 O 7−δ (YBCO) superconductors with embedded Y 2 BaCuO 5 (Y-211) nanoparticles. By means of focused ion-beam (FIB) milling, TEM slices were prepared from mechanically polished surfaces of bulk, IG-processed YBCO samples. The required optical transparency was reached by additional polishing the resulting surfaces using the FIB and Ar-ion milling. For TKD, the sample was mounted on a homebuilt sample holder in the SEM, which provides the required inclination for TKD. The improved spatial resolution of TKD enabled the investigation of the small Y-211 particles (diameter of about 60-210 nm) embedded in the superconducting YBCO matrix. The fabricated TEM slices further enable the application of transmission electron microscopy to the same sample sections. These tiny Y-211 particles embedded within the YBCO matrix are, together with their strain fields, directly responsible for the high irreversibility fields due to the effective flux pinning of the IG-processed samples.

“…Polycrystalline samples are thus expected and were obtained. Different set-ups can be used [13,[26][27][28], We have studied two of these. In the first case, 211-particles and flux precursors are fully mixed together and uniaxially pressed to form the green body ( figure 3(a)).…”

Section: Methodsmentioning

confidence: 99%

“…Dy-123 can also be used as a flux precursor [26]. In this case, the maximum processing temperature must be above the peritectic temperature of the Dy-123 phase and the as-obtained flux will contain some dissolved dysprosium ions.…”

Section: Infiltration and Growth Processmentioning

confidence: 99%

Investigation of DyBa₂Cu₃O_7−d superconducting domains grown by the infiltration technique starting with small size Dy-211 particles

Mathieu

Koutzarova

Rulmont

et al. 2004

An infiltration and growth process is here used as an alternative to the classical top-seeded melt-textured growth process for the production of Dy-123 single-domains with finely dispersed small size Dy-211 particles. The starting materials are the 211-particles and a barium and copper rich liquid phase precursor. The infiltration and growth process allows for controlling both the spatial and size distribution of the 211-particles in the final superconducting 123-single-domain. The main parameters (set-ups, maximum processing temperature with respect to the peritectic temperature, nature of reactant, porosity of the 211 -preform) of the infiltration and growth process are discussed. Moreover, different processes of chimie douce are shown in order to produce Dy-211 particles with controlled shape and size, particles that can be used as precursors for the infiltration and growth process.