scholarly journals Attraction and repulsion forces in melt-textured and sintered YBCO-superconductors: a comparative study

2020 ◽  
pp. 44-50
Author(s):  
Diego Andrés Arias-Arana ◽  
Juan Diego Rojas-Zambrano ◽  
Álvaro Mariño-Camargo
Keyword(s):  
Low Cost ◽  
Sintered Sample ◽  
Interaction Force ◽  
Solid State Reaction Method ◽  
Zero Field ◽  
Bulk Superconductors ◽  
Ybco Superconductors ◽  
Growth Method ◽  
Magnetic Flux Pinning ◽  
Field Cooling

In this paper, we measure the attraction (suspension) and repulsion (levitation) forces produced by the interaction between a permanent magnet and different bulk superconductors. The measurements of the interaction force HTS-PM were carried out with a relatively simple technique developed by us, which is reproducible, reliable and low cost. The obtained results were analyzed with the Bean’s critical-state model assuming a uniform magnetic field applied to the superconductor. Two superconducting samples of YBa2Cu3O7-δ (YBCO) prepared by solid-state reaction method and by the melt-textured growth method (MTG) were used. Both samples presented a different hysteresis behaviour in the field cooling (FC) and zero field cooling (ZFC) regimes. Levitation and suspension phenomena were observed in the MTG sample; however, the sintered sample (S) with Oxygen deficiencies (δ > 0.15) displayed a slight levitation force but did not show a suspension force, the latter one attributed to a more efficient magnetic flux pinning. Additionally, the critical current density of both samples was determined from the maximum gap of the force (ΔF) in the FC regime. The obtained values were between 43.00 A/cm2 and 2,758 A/cm2 for the sintered and MTG samples, respectively. These values show a remarkable difference between sintered and MTG samples like that observed from magnetization measurements, which indicate that attraction and repulsion force measurements could provide a rapid and reliable characterization method of polycrystalline superconducting samples.  

scholarly journals LEVITATION AND SUSPENSION FORCES MEASUREMENT SYSTEM FOR HIGH TC SUPERCONDUCTORS

MOMENTO ◽  
2020 ◽  
pp. 55-66 ◽  
Author(s):  
Juan D. Rojas ◽  
Diego A. Arias ◽  
Alvaro Mariño
Keyword(s):  
Levitation Force ◽  
Low Cost ◽  
Hysteresis Loops ◽  
Solid State Reaction Method ◽  
Zero Field ◽  
High Tc Superconductors ◽  
Interaction Forces ◽  
High Tc ◽  
Large Hysteresis ◽  
Growth Method

The interaction forces, attraction (suspension) and repulsion (levitation) between a permanent magnet and diferent bulk Yttrium-based superconductors were carried out with an automatic system developed in our group, which is reproducible, reliable and low cost. Two superconducting samples of YBa2Cu3O7-δ (YBCO) prepared by solid-state reaction method (S) and by the melt-textured growth method (MTG) were used. Both samples were characterized by XRD technique and presented the characteristic peaks and intensity relations of the YBCO-123 superconducting phase. Oxygen deficiencies δ > 0,15 and δ < 0,10 for the S and MTG samples respectively, were observed. Both samples displayed diferent hysteresis behavior in the Force (F) vs. Distance (z) measurements when they were field cooled (FC) and zero field cooled (ZFC). This behavior agrees with hysteresis loops observed in magnetization measurements. Both levitation and suspension phenomena were observed in the MTG sample with large hysteresis loops of the force. On the contrary, the S sample with small hysteresis loops did not show a suspension force, only displayed a slight levitation force.

INFLUENCE OF WAITING TIME ON THE LEVITATION FORCE BETWEEN A PERMANENT MAGNET AND A SUPERCONDUCTOR

2008 ◽  
Vol 22 (07) ◽  
pp. 499-506 ◽  
Author(s):  
XING-YI ZHANG ◽  
YOU-HE ZHOU ◽  
JUN ZHOU
Keyword(s):  
Permanent Magnet ◽  
Liquid Nitrogen ◽  
Waiting Time ◽  
Levitation Force ◽  
Liquid Nitrogen Temperature ◽  
Zero Field ◽  
Bulk Superconductors ◽  
Growth Method ◽  
Ndfeb Permanent Magnet ◽  
Ybacuo Bulk

This paper describes the experimental results of the levitation force of single-grained YBaCuO bulk superconductors preparing by the top-seeded melt-growth method with different waiting time tw below an NdFeB permanent magnet. It was found that waiting time has large effects on the zero-field-cooled (ZFC) and field-cooled (FC) levitation force, and the levitation force shows aging characteristics at the liquid nitrogen temperature.

Fracture analysis of a central crack in a long cylindrical superconductor with exponential model

2018 ◽  
Vol 32 (14) ◽  
pp. 1850145 ◽  
Author(s):  
Yu Feng Zhao ◽  
Chi Xu
Keyword(s):  
Fracture Behavior ◽  
High Temperature Superconductors ◽  
Crack Problem ◽  
Exponential Model ◽  
Zero Field ◽  
The Finite Element Method ◽  
Central Crack ◽  
Bulk Superconductors ◽  
Different Characteristics ◽  
Field Cooling

The fracture behavior of a long cylindrical superconductor is investigated by modeling a central crack that is induced by electromagnetic force. Based on the exponential model, the stress intensity factors (SIFs) with the dimensionless parameter p and the length of the crack a/R for the zero-field cooling (ZFC) and field-cooling (FC) processes are numerically simulated using the finite element method (FEM) and assuming a persistent current flow. As the applied field [Formula: see text] decreases, the dependence of p and a/R on the SIFs in the ZFC process is exactly opposite to that observed in the FC process. Numerical results indicate that the exponential model exhibits different characteristics for the trend of the SIFs from the results obtained using the Bean and Kim models. This implies that the crack length and the trapped field have significant effects on the fracture behavior of bulk superconductors. The obtained results are useful for understanding the critical-state model of high-temperature superconductors in crack problem.

scholarly journals Bio-Separated and Gate-Free 2D MoS2 Biosensor Array for Ultrasensitive Detection of BRCA1

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 545
Author(s):  
Yi Zhang ◽  
Wei Jiang ◽  
Dezhi Feng ◽  
Chenguang Wang ◽  
Yi Xu ◽  
...  
Keyword(s):  
High Performance ◽  
Low Cost ◽  
Chemical Vapor ◽  
Signal Interference ◽  
Ultrasensitive Detection ◽  
Chemical Vapor Deposition Growth ◽  
Biosensor Array ◽  
Growth Method ◽  
Biological Modification ◽  
Biological Solutions

2D molybdenum disulfide (MoS2)-based thin film transistors are widely used in biosensing, and many efforts have been made to improve the detection limit and linear range. However, in addition to the complexity of device technology and biological modification, the compatibility of the physical device with biological solutions and device reusability have rarely been considered. Herein, we designed and synthesized an array of MoS2 by employing a simple-patterned chemical vapor deposition growth method and meanwhile exploited a one-step biomodification in a sensing pad based on DNA tetrahedron probes to form a bio-separated sensing part. This solves the signal interference, solution erosion, and instability of semiconductor-based biosensors after contacting biological solutions, and also allows physical devices to be reused. Furthermore, the gate-free detection structure that we first proposed for DNA (BRCA1) detection demonstrates ultrasensitive detection over a broad range of 1 fM to 1 μM with a good linear response of R2 = 0.98. Our findings provide a practical solution for high-performance, low-cost, biocompatible, reusable, and bio-separated biosensor platforms.

scholarly journals Research of Fluorescent Properties of a New Type of Phosphor with Mn2+-Doped Ca2SiO4

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2788
Author(s):  
Xiaozhou Fan ◽  
Wenqi Zhang ◽  
Fangcheng Lü ◽  
Yueyi Sui ◽  
Jiaxue Wang ◽  
...  
Keyword(s):  
Electromagnetic Interference ◽  
Green Emission ◽  
Response Speed ◽  
Sintered Sample ◽  
Solid State Reaction Method ◽  
Average Lifetime ◽  
Diffraction Spectrum ◽  
Fluorescent Properties ◽  
Fluorescent Material ◽  
New Type

Fluorescent optical fiber temperature sensors have attracted extensive attention due to their strong anti-electromagnetic interference ability, good high-voltage insulation performance, and fast response speed. The fluorescent material of the sensor probe directly determines the temperature measurement effect. In this paper, a new type of fluorescent material with a Mn2+-doped Ca2SiO4 phosphor (CSO:Mn2+) is synthesized via the solid-state reaction method at 1450 °C. The X-ray diffraction spectrum shows that the sintered sample has a pure phase structure, although the diffraction peaks show a slight shift when dopants are added. The temperature dependence of the fluorescence intensity and lifetime in the range from 290 to 450 K is explored with the help of a fluorescence spectrometer. Green emission bands peaking at 475 and 550 nm from Mn2+ are observed in the fluorescence spectra, and the intensity of emitted light decreases as the temperature rises. The average lifetime of CSO:Mn2+ is 17 ms, which is much higher than the commonly used fluorescent materials on the market. The fluorescence lifetime decreases with increasing temperature and shows a good linear relationship within a certain temperature range. The research results are of great significance to the development of a new generation of fluorescence sensors.

Surface Effects on the Magnetic Behavior of Nanocrystalline Nickel Ferrites: The Effect of Surface Roughness and Dilution

2005 ◽  
Vol 877 ◽  
Author(s):  
H. Nathani ◽  
R.D.K. Misra ◽  
W.F. Egelhoff
Keyword(s):  
Surface Roughness ◽  
Nickel Ferrite ◽  
Magnetic Measurements ◽  
Magnetic Behavior ◽  
Magnetic Data ◽  
Zero Field ◽  
Nanocrystalline Nickel ◽  
Polyethylene Matrix ◽  
Dilution Effects ◽  
Field Cooling

AbstractThe paper describes the surface roughness and dilution effects on the magnetic behavior of nanocrystalline nickel ferrites studied by SQUID magnetometer. Two different kinds of measurements were performed: (a) zero-field cooling (ZFC) and field cooling (FC) magnetization versus temperature and (b) magnetization as a function of the applied field. The analysis of magnetic measurements indicate that while the superparamagnetic behavior is retained by nanocrystalline ferrites of different surface roughness (0.8-1.8 nm) at 300K, the hysteresis loop at 2K becomes non-squared and the coercivity increases with increase in surface roughness. This behavior is discussed in terms of broken bonds and degree of surface spin disorder. In diluted dispersion systems containing 10-40% nickel ferrite in a polyethylene matrix, the interparticle attractions continue to be dominant even when the concentration of nickel ferrite is 10 wt.% in the diluted system. The general magnetic behavior of diluted dispersion system is similar to the undiluted system; however, coercivity, remanence, and saturation magnetization are altered. These changes in the magnetic data are ascribed to magnetization interactions that encourage flux closure configuration.

scholarly journals Síntesis del superconductor YBa2Cu3O7- δ mediante sinterización por descarga luminiscente anormal

2017 ◽  
Vol 41 (158) ◽  
pp. 36
Author(s):  
Erika Yazmin Soto-Gómez ◽  
Armando Sarmiento-Santos ◽  
Carlos Arturo Parra-Vargas
Keyword(s):  
Zero Field ◽  
Zero Field Cooling ◽  
Field Cooling

En este trabajo se reporta la síntesis del superconductor YBa2Cu3O7-δ mediante el método no convencional de sinterización por plasma en el rango de descarga luminiscente anormal (DLA). Las muestras se sometieron a diferentes temperaturas y tiempos de sinterización. Como referencia se usó una muestra superconductora obtenida por el método convencional (horno resistivo). La caracterización estructural de estas muestras se hizo por difracción de rayos X y refinamiento con el método de Rietveld. El comportamiento superconductor se determinó mediante el análisis de las curvas de magnetización en función de la temperatura según los procedimientos experimentales de enfriado en campo magnético cero (zero field cooling, ZFC) y enfriado con campo magnético aplicado (field cooling, FC). Las muestras sinterizadas por DLA presentaron características estructurales (ortorrómbica Pmmm) y superconductoras con una temperatura crítica de Tc~ 92 K, similares a las obtenidas por el método convencional, pero con una significativa reducción en las temperaturas y tiempos, bajo un ambiente adecuado de presión en el proceso de sinterización. © 2017. Acad. Colomb. Cienc. Ex. Fis. Nat.

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