Nano-SQUIDs with controllable weak links created via current-induced atom migration

Nanoscale ◽  
2018 ◽  
Vol 10 (45) ◽  
pp. 21475-21482 ◽  
Author(s):  
Wout Keijers ◽  
Xavier D. A. Baumans ◽  
Ritika Panghotra ◽  
Joseph Lombardo ◽  
Vyacheslav S. Zharinov ◽  
...  
Keyword(s):  
Weak Link ◽  
Weak Links ◽  
Atom Migration ◽  
Atom Displacement

Weak link modification through current-induced atom displacement in order to tune the SQUID's response.

3-D Characterization of Global and Local Microstructural Effects on Spall Damage in Shock Loaded FCC Metals: Experimental and Modeling

2013 ◽  
Author(s):  
A. Brown ◽  
K. Krishnan ◽  
L. Wayne ◽  
P. Peralta ◽  
S. N. Luo ◽  
...  
Keyword(s):  
Weak Link ◽  
Heat Treatments ◽  
Taylor Factor ◽  
Weak Links ◽  
Spall Damage ◽  
Heat Treated ◽  
Microstructural Effects ◽  
Global And Local ◽  
Low Pressures

Global and local microstructural weak links for spall damage were investigated using 3-D characterization in polycrystalline (PC) and multicrystalline (MC) copper samples, respectively. All samples were shocked via flyer-target plate experiments using a laser drive at low pressures (2–6 GPa). The flyer plates measured approximately 500 μm thick and 8 mm in diameter and the target plates measured approximately 1000 μm thick and 10 mm in diameter. Electron Backscattering Diffraction (EBSD) and optical microscopy were used to determine to presence of voids and relate them to the surrounding microstructure. Statistics on the strength of grain boundaries (GBs) was conducted by analyzing PC samples and collecting the misorientation across GBs with damage present, and it was found that a misorientation range of 25–50° is favorable for damage. Statistics were also taken of copper PC samples that had undergone different heat treatments and it was found that although the 25–50° range is less dominant, it is still favorable for damage nucleation. Removal of initial plastic strain via heat treatments and an increase in Σ3 CSL boundaries, indicative of strong annealing twins, also led to an increased amount of transgranular damage. 3-D X-ray tomography data were used to investigate the shape of the voids present in untreated, as received and heat treated samples. It was found that the as received sample contained a higher amount of “disk”, or, “sheet-like” voids indicative of intergranular damage, whereas the heat treated samples had a higher fraction of spherical shaped voids, indicative of transgranular damage. MC samples were used to study microstructural weak links for spall damage because the overall grain size is much larger than the average void size, making it possible to determine which GBs nucleated damage. Simulations and experimental analysis of damage sites with large volumes indicate that high Taylor factor mismatches with respect to the crystallographic grain GB normal is the primary cause for the nucleation of damage at a GB interface and a low Taylor factor along the shock direction in either grain drives void growth perpendicular to the GB. Cases where experimental results show damage and simulation results show no damage are attributed to the presence of an intrinsic microstructural weak link, such as an incoherent twin boundary.

VOLTAGE-CURRENT CHARACTERISTICS AND MAGNETORESISTANCE OF BiPbSrCaCuO SILVER CLAMP THICK FILM

1992 ◽  
Vol 06 (26) ◽  
pp. 1639-1647 ◽  
Author(s):  
HAN GUCHANG ◽  
WANG YUGUI ◽  
HAN HANMIN ◽  
WANG SHUNXI
Keyword(s):  
Thick Film ◽  
Weak Link ◽  
Weak Links ◽  
Flux Flow ◽  
Type Ii Superconductors ◽  
Flux Lines ◽  
Flux Trapping ◽  
Physical Deposition ◽  
History Effect ◽  
Current Characteristics

Bi(2223) silver clamp thick film with Jc=1.5×104A/cm2 at 77 K and 0 T was fabricated by a physical deposition method. Voltage-current characteristics and magnetoresistance were investigated in detail at low magnetic fields. It can be concluded that the transport Jc limitation of the present samples was still dominated by weak links although their connectivity has been greatly improved in comparison with bulk materials. The weak links may exert an effective pinning on flux lines. When the transport current exceeds the critical current of weak links their resistances change, just as does the flux flow resistance of traditional type-II superconductors. A history effect of the magnetoresistivity below a certain field (about 1.0 kG) was found at various constant measuring currents and can be ascribed to the Jc (H) characteristics and flux trapping both in the weak link network and the grains.

Research on Machine Tool Components Contribution Calculation and the Weak Link Identification of the Whole Machine

2011 ◽  
Vol 52-54 ◽  
pp. 1496-1502
Author(s):  
Hong Lin Zhao ◽  
Qing Fu Wang ◽  
Wei Hua Li ◽  
Guang Peng Zhang ◽  
Zhi Heng Wu ◽  
...  
Keyword(s):  
Weak Link ◽  
General Structure ◽  
Weak Links ◽  
Work Piece ◽  
Space Vector ◽  
Finite Element Software ◽  
Weakest Link ◽  
Vertical Milling ◽  
Vertical Milling Machine ◽  
Key Nodes

After modeling and calculating of whole machine, the static and dynamic characteristics are obtained, since it is difficult not only to judge out machine components’ influence on machining precision intuitively , but also to identify the weak link of the whole machine. Therefore, through extracting key nodes coordinates of machine components and deformation information of finite element software calculated, we brought forward a space vector transfer algorithm, calculated the contribution of components for tools and work piece system and expressed impact of machine components on tool and work piece system by histogram. By this means ,we can judge out the whole machine’s weak links intuitively. Take XK713B Vertical Milling Machine as the case research object, extract key nodes and their deformation information of general structure such as lathe bed , column, headstock, sliding table, workbench etc. By using space vector transfer algorithm, the result shows that the largest contribution to tool system and workbench system is column, which is the weakest link in the whole machine and its vibration type is swing. According to this, further optimize design of column can be proceed.

Transport Measurements on Superconducting YBa2Cu3O7-δ Thin Film Lines

1989 ◽  
Vol 169 ◽  
Author(s):  
B. H. Moeckly ◽  
D. K. Lathrop ◽  
G. F. Redinbo ◽  
S. E. Russek ◽  
R. A. Buhrman
Keyword(s):  
Magnetic Field ◽  
Thin Film ◽  
Critical Current ◽  
Weak Link ◽  
High Sensitivity ◽  
Weak Links ◽  
Microwave Response ◽  
Field Response ◽  
Current Densities ◽  
Iv Curves

AbstractCritical current densities, magnetic field response, and microwave response have been measured for laser ablated YBa2Cu3O7-δ thin film lines on MgO and SrTiO3 substrates. Films on SrTiO3 have critical current densities > 1 x 106 A/cm2 at 77K and show uniform transport properties in lines of all sizes. Films on MgO have critical current densities which range between 102 and 106 A/cm2 at 77K and show considerable variation from device to device on the same chip. Narrow lines on MgO with low critical current densities show Josephson weak link structure which includes RSJ-like IV curves, microwave induced constant voltage steps, and a high sensitivity to magnetic field. The presence of the Josephson weak links is correlated with small amounts of misaligned grains in films on MgO.

(001) grain boundaries in Ag-clad Bi2Sr2Ca1Cu2O8+y (BSCCO) tapes

1991 ◽  
Vol 49 ◽  
pp. 1088-1089
Author(s):  
Y. Feng
Keyword(s):  
Grain Boundaries ◽  
Cuprate Superconductors ◽  
Weak Link ◽  
Weak Field ◽  
Weak Links ◽  
Great Promise ◽  
Core Thickness ◽  
Current Densities ◽  
Powder In Tube ◽  
Very High

Recently, Ag-clad tapes of Bi-cuprate superconductors have shown great promise for application as conductors in very high magnetic fields at temperature 4-20 K. High critical current densities (Jc) with weak field dependence indicate that the powder-in-tube process can drastically reduce the effect of grain boundary weak links at 4-20 K. It is thus of great interest to study the grain boundaries in the Ag-clad BSCCO tapes to understand their effect on the Jc.BSCCO Ag-clad wires with 2:2:1:2 starting composition were drawn and rolled to rectangular tapes (0.1 x 3 mm) with BSCCO core thickness of 45μm. The sample was heated at 920°C for 15 minutes, cooled to 840°C at 10°C/h, then annealed at 840°C for 70 h. The measured Jc values exceed 2x104 A/cm2 (5T, 4.2K) and do not exhibit obvious weak link behaviour. In order to investigate the (001) grain boundaries, samples were made by bonding several tapes together along their broad face. Thin longitudinal slices were cut and then ion milled at 4.5 kV in liquid nitrogen. TEM was carried out by using a JEOL 200CX-II at 200 kV.

Microstructure of thin YBa2Cu3O7−δ films

1990 ◽  
Vol 48 (4) ◽  
pp. 8-9
Author(s):  
M. Grant Norton ◽  
C. Barry Carter
Keyword(s):  
Thin Films ◽  
Film Growth ◽  
Weak Link ◽  
Critical Currents ◽  
Weak Links ◽  
High Tc ◽  
Fundamental Interest ◽  
Early Stages ◽  
Transmission Electron ◽  
Patterned Films

The microstructure of superconducting thin-films often strongly influences their electrical properties. The actual microstructure of the film will be dependent on the nucleation and early stages of film growth, although the substrate will also be expected to exert an influence during the early stages of growth by the establishment of epitaxy. The highest critical currents have been obtained with films grown on SrTiO3, however MgO is of fundamental interest because patterned films on MgO have been shown to possess Josephson weak-link structure. The presence of the Josephson weak-links has been correlated with the occurrence of misaligned grains in films grown on MgO. Ultra-thin films of high-Tc superconductors are of interest for understanding the properties of these materials and may also be of use in technical applications.The microstructure of ultra-thin YBa2Cu3O7−δ films prepared by pulsed-laser ablation onto (001)- oriented MgO has been studied using transmission electron microscopy (TEM) and selected-area diffraction (SAD).

New technology and the chain of safety

2016 ◽  
Vol 30 (1) ◽  
pp. 4-9
Author(s):  
Rob Martell ◽  
Jason T. Macartney ◽  
Danielle Portnik
Keyword(s):  
Patient Safety ◽  
Airline Industry ◽  
Medical Technology ◽  
Weak Link ◽  
Improve Patient Safety ◽  
New Technology ◽  
Healthcare Setting ◽  
Weak Links ◽  
Frontline Staff ◽  
Improve Patient

Healthcare is currently experiencing an exponential growth in medical technology but it has not kept pace with similar industries such as the airline industry. New technology has the potential to improve patient safety, but if the introduction of new technology into the healthcare setting is not coordinated in a thoughtful, proactive manner, there may be weak links in the chain of safety that may expose risks for patients. We describe three concepts that represent this chain of safety. We suggest that these are shared among all leadership and frontline staff and that these concepts require their full attention and investment in order to keep the chain of safety intact and avoid a single weak link in implementing new technology.

Effect of the Weak Links on the Surface Resistance of YBa2Cu3Ox Bulk Material

1992 ◽  
Vol 275 ◽  
Author(s):  
J. Wosik ◽  
L. M. Xie ◽  
J. Halbritter ◽  
R. Chau ◽  
A. Samaan ◽  
...  
Keyword(s):  
Surface Resistance ◽  
Weak Link ◽  
Bulk Material ◽  
Weak Links ◽  
Wave Surface ◽  
Critical Fields ◽  
High Quality ◽  
Dc Magnetic Field ◽  
Replacement Method ◽  
Field Temperature

ABSTRACTDc magnetic field, temperature, and magnetic history dependencies of the millimeter-wave surface resistance have been measured in high quality grain-aligned and in polycrystalline YBa2Cu3Ox bulk material. The measurements were carried at 75 GHz using the endplate of the cavity replacement method. The data is interpreted in terms of the presence of intra- and inter-grain types of weak links. The values of characteristic critical fields of the bulk and the weak link junctions are determined and discussed.

The amorphization of complex silicates by ion-beam irradiation

1992 ◽  
Vol 7 (11) ◽  
pp. 3080-3102 ◽  
Author(s):  
Ray K. Eby ◽  
Rodney C. Ewing ◽  
Robert C. Birtcher
Keyword(s):  
Melting Point ◽  
Regression Models ◽  
Ion Irradiation ◽  
Weak Link ◽  
Ion Beam ◽  
Covalent Bond ◽  
Weak Links ◽  
Bond Ionicity ◽  
Data Set ◽  
Atomic Packing

Twenty-five silicates were irradiated at ambient temperature conditions with 1.5 MeV Kr+. Critical doses of amorphization were monitored in situ with transmission electron microscopy. The doses required for amorphization are compared with the structures, bond-types, compositions, and physical properties of the silicates using simple correlation methods and more complex multivariate statistical analysis. These analyses were made in order to determine which properties most affect the critical amorphization dose. Simple two-variable correlations indicate that melting point, efficiency of atomic packing, the dimensionality of SiO4 polymerization (DOSP), and bond ionicity have a relationship with critical amorphization dose. However, these relationships are evident only in selected portions of the data set; that is, for silicate phases with a common structure type. A clearer relationship between the silicate properties and critical amorphization dose was determined for the entire data set with multiple linear regression. Several regression models are proposed which describe the variation in amorphization dose. All regression models contain the following properties: (i) melting point; (ii) a structural variable (DOSP, elastic modulus, and/or atomic packing); and (iii) the proportion of Si–O bonding (instead of bond ionicity). The regression models are equivalent, because they represent combinations of similar properties. Notably, density and atomic mass are not controlling properties for the critical amorphization dose. Melting and amorphization by ion irradiation are apparently related processes. Neither melting point nor critical amorphization dose can be predicted by considering only the structure, composition, or bonding of a particular phase. The Si–O bond is the most covalent bond in silicates, and is the “weak link” in the structure with respect to amorphization. Thus, DOSP is also an important property, as the topology of these “weak links” influences a structure's ability to accumulate amorphous regions. The efficiency of atomic packing is related to the process of defect self-recombination during amorphization. The bulk modulus and shear modulus are important variables within the regression models because of their direct relationship to atomic packing.

Microtexture Mapping of Elecrtron Backscattered Diffraction in (Bi,Pb)2Sr2Ca2Cu3O10 Superconductor Tapes

2000 ◽  
Vol 659 ◽  
Author(s):  
Sean Li ◽  
Thiam Teck Tan
Keyword(s):  
Critical Current Density ◽  
Grain Boundaries ◽  
Critical Current ◽  
Current Density ◽  
Crystallographic Orientation ◽  
Weak Link ◽  
Large Angle ◽  
Orientation Distribution ◽  
Weak Links ◽  
Electron Backscattered Diffraction

ABSTRACTGrain boundaries is believed to act as weak-links limiting the critical current density (Jc) of bulk high-Tcsuperconductors. The weak-link problem can be greatly reduced by elimination or minimization of the large-angle grain boundaries. It has been reported that the Jc distribution in the transverse cross-section of (Bi,Pb)2Sr2Ca2Cu3O10+x (Bi2223) superconductor tapes follows a parabolic relationship, with the lowest currents occurring at the center of the tapes. The Jc distribution is proposed to be strongly dependent on the local crystallographic orientation distribution of the Bi2223 oxides. However, the local three dimensional crystallographic orientation distribution of Bi2223 crystals in (Bi,Pb)2Sr2Ca2Cu3O10+×superconductor tapes has not been experimentally determined yet. In this work, Electron Backscattered Diffraction technique was employed to map the crystallographic orientation of the crystals in Bi2223 superconductor tapes. From this, the misorientation of grain boundaries and also their distribution are obtained. Through crystallographic orientation mapping, the relationship of the crystallographic orientation distribution, the boundary misorientation distribution and the fabrication parameters may be understood. This can be used to optimize the fabrication processes thus increasing the critical current density in Bi2223 superconductor tapes.

Sign in / Sign up

Export Citation Format

Share Document