Low-temperature increase of resistive critical fields in certain superconductors: A simple fluctuation approach

1995 ◽  
Vol 51 (9) ◽  
pp. 6179-6182 ◽  
Author(s):  
J. R. Cooper ◽  
J. W. Loram ◽  
J. M. Wade
Keyword(s):  
Low Temperature ◽  
Temperature Increase ◽  
Critical Fields

How Measurements of Rate Coefficients at Low Temperature Increase the Predictivity of Photochemical Models of Titan’s Atmosphere†

2009 ◽  
Vol 113 (42) ◽  
pp. 11227-11237 ◽  
Author(s):  
E. Hébrard ◽  
M. Dobrijevic ◽  
P. Pernot ◽  
N. Carrasco ◽  
A. Bergeat ◽  
...  
Keyword(s):  
Low Temperature ◽  
Temperature Increase ◽  
Rate Coefficients ◽  
Photochemical Models

Anisotropic Upper Critical Field of Single Crystal RNi2B2C (R = Y, Lu)

1998 ◽  
Vol 12 (29n31) ◽  
pp. 3264-3266 ◽  
Author(s):  
A. C. Du Mar ◽  
K. D. D. Rathnayaka ◽  
D. G. Naugle ◽  
P. C. Canfield
Keyword(s):  
Low Temperature ◽  
Single Crystal ◽  
Critical Field ◽  
Upper Critical Field ◽  
Critical Fields ◽  
Linear Behavior ◽  
Upward Curvature

Measurements of the anisotropic upper critical field curves have been extended for YNi 2B2C and LuNi2B2C (T c = 15.6 K and 16.1 K, respectively). Measurements of R(T, H) were taken along the crystallographic directions of <100> and <110>. The resulting critical fields show an upward curvature near T c and a linear behavior at low temperature, which continues to below 2 K with little, if any, sign of saturation.

Influence of lime (CaO) on low temperature leaching of some types of bauxite from Guinea

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Marie Constance Béavogui ◽  
Irina Viktorovna Loginova ◽  
Ahmed Amara Konaté ◽  
Sékou Amadou Condé
Keyword(s):  
Chemical Composition ◽  
Low Temperature ◽  
Temperature Increase ◽  
Temperature Treatment ◽  
Bayer Process ◽  
Leaching Rate ◽  
Low Temperature Treatment ◽  
Leaching Efficiency

Abstract In Bayer process, low temperature treatment of bauxite generally applicable to gibbsite in the presence of a significant amount of boehmite (>3%), requires a temperature increase and the addition of an additive to improve the leaching conditions. This research is based on improvement of low temperature leaching conditions 108 °C and the addition of lime during the attack of some types of bauxite in Guinea. TRUhat is Low Mono Grade Bauxite (LMG), Standard Metal Grade (SMG) and Fria Bauxite (BF). The results of this study confirm an improvement in the extraction yields. Additionally, it shows an increase in yields of two points when the lime dosage is low, and between 0.5 and 3% of the bauxite weight. Based on the mineralogical and chemical composition findings, minerals contain of SMG bauxites are difficult to decompose while BF bauxites are easy to process. Sougueta limestone was used for testing. After calcination, we obtained CaO added at a rate of: 0.3; 0.5; 1; 3 and 6% of the bauxite weight to finally obtain the highest leaching efficiency compared to the leaching efficiency of bauxite without addition. The best leaching rate obtained for LMG, SMG and BF are respectively: 89.01, 87.15 and 89.74% for additions of 1, 0.5 and 3% CaO respectively.

Advances in Bi-Based High-Tc Superconducting Tapes and Wires

MRS Bulletin ◽  
2001 ◽  
Vol 26 (2) ◽  
pp. 121-125 ◽  
Author(s):  
Hitoshi Kitaguchi ◽  
Hiroaki Kumakura
Keyword(s):  
Low Temperature ◽  
High Field ◽  
Superconducting Magnet ◽  
Oxide Superconductors ◽  
Critical Fields ◽  
High Tc ◽  
Practical Applications ◽  
High Transition ◽  
Promising Application ◽  
Upper Critical Fields

Since the discovery of high-Tc superconductors (HTSs), especially the Bi-based oxide superconductors (Bi-HTSs) in 1989, much effort has been concentrated on the fabrication of Bi-HTS wires and tapes. Bi-HTSs are interesting materials from the viewpoint of practical applications. One of the interesting applications of Bi-HTSs is the cryogen-free conduction-cooled magnet. Besides having a high transition tem- perature (Tc), Bi-HTSs have high upper critical fields (Bc2) or high irreversibility fields (Birr) at temperatures below ∼30 K. Because ∼30 K can be efficiently main- tained by a cryocooler, a Bi-HTS magnet cooled with a cryocooler has great potential in many technological applications. Another promising application of Bi-HTSs is the high-field magnet. When the temperature is reduced to ∼5 K, Bi-HTSs show a much higher Bc2 or Birr than do conventional metallic superconductors (low-temperature superconductors, LTSs) such as Nb3Sn. This indicates that Bi-HTSs also have great potential for use in a high- field superconducting magnet if the magnet is operated at low temperature.

Low-Temperature Transport Properties of Graphene and Multilayer Graphene on 6H-SiC

2013 ◽  
Vol 740-742 ◽  
pp. 137-140 ◽  
Author(s):  
Alexander A. Lebedev ◽  
Nina V. Agrinskaya ◽  
Viacheslav A. Berezovets ◽  
Veniamin I. Kozub ◽  
Sergey P. Lebedev ◽  
...  
Keyword(s):  
Low Temperature ◽  
Transport Properties ◽  
Temperature Increase ◽  
Weak Localization ◽  
Multilayer Graphene ◽  
Temperature Resistance ◽  
Shubnikov De Haas Oscillations ◽  
Low Temperature Resistance ◽  
Observed Behavior

Transport properties of multigraphene layers on 6H-SiC substrates was studied. It was found that the curves of magnetoresistance and Shubnikov- de Haas oscillations shown the features, typical for single-layred graphene. The low temperature resistance demonstrated an increase with temperature increase, which also corresponds to a behavior typical for single-layered graphene (antilocalization). However at higher temperatures the resistance decreased with an increase of temperature, which corresponds to a weak localization. We believe that the observed behavior can be explained by a parallel combination of contributions to the conductivity of single-layered graphene and of multigraphene.

Exsolution and inversion in pigeonite from the Whin Sill, Northern England

1978 ◽  
Vol 36 (1) ◽  
pp. 474-475
Author(s):  
P.P.K. Smith
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Homogeneous Nucleation ◽  
Silicate Mineral ◽  
Antiphase Boundaries ◽  
Two Phase ◽  
Primitive Form ◽  
The Core ◽  
Nucleation Mechanisms ◽  
And Inversion

Grains of pigeonite, a calcium-poor silicate mineral of the pyroxene group, from the Whin Sill dolerite have been ion-thinned and examined by TEM. The pigeonite is strongly zoned chemically from the composition Wo8En64FS28 in the core to Wo13En34FS53 at the rim. Two phase transformations have occurred during the cooling of this pigeonite:- exsolution of augite, a more calcic pyroxene, and inversion of the pigeonite from the high- temperature C face-centred form to the low-temperature primitive form, with the formation of antiphase boundaries (APB's). Different sequences of these exsolution and inversion reactions, together with different nucleation mechanisms of the augite, have created three distinct microstructures depending on the position in the grain.In the core of the grains small platelets of augite about 0.02μm thick have farmed parallel to the (001) plane (Fig. 1). These are thought to have exsolved by homogeneous nucleation. Subsequently the inversion of the pigeonite has led to the creation of APB's.

Low temperature x-ray microanalysis of frozen-hydrated tobacco leaves

1984 ◽  
Vol 42 ◽  
pp. 284-285
Author(s):  
S. Edith Taylor ◽  
Patrick Echlin ◽  
May McKoon ◽  
Thomas L. Hayes
Keyword(s):  
Low Temperature ◽  
Lemna Minor ◽  
Root Tips ◽  
Tobacco Leaves ◽  
X Ray ◽  
Whole Cells ◽  
Carbon Coated ◽  
The Right ◽  
Beam Currents ◽  
The University

Low temperature x-ray microanalysis (LTXM) of solid biological materials has been documented for Lemna minor L. root tips. This discussion will be limited to a demonstration of LTXM for measuring relative elemental distributions of P,S,Cl and K species within whole cells of tobacco leaves.Mature Wisconsin-38 tobacco was grown in the greenhouse at the University of California, Berkeley and picked daily from the mid-stalk position (leaf #9). The tissue was excised from the right of the mid rib and rapidly frozen in liquid nitrogen slush. It was then placed into an Amray biochamber and maintained at 103K. Fracture faces of the tissue were prepared and carbon-coated in the biochamber. The prepared sample was transferred from the biochamber to the Amray 1000A SEM equipped with a cold stage to maintain low temperatures at 103K. Analyses were performed using a tungsten source with accelerating voltages of 17.5 to 20 KV and beam currents from 1-2nA.

Bulk standards for low-temperature biological x-ray microanalysis

1984 ◽  
Vol 42 ◽  
pp. 282-283
Author(s):  
P. Echlin ◽  
M. McKoon ◽  
E.S. Taylor ◽  
C.E. Thomas ◽  
K.L. Maloney ◽  
...  
Keyword(s):  
Phase Separation ◽  
Low Temperature ◽  
Analytical Method ◽  
Salt Solutions ◽  
Absolute Concentration ◽  
Cooling Process ◽  
X Ray ◽  
The Absolute ◽  
Analytical Procedures ◽  
Electrical Conductors

Although sections of frozen salt solutions have been used as standards for x-ray microanalysis, such solutions are less useful when analysed in the bulk form. They are poor thermal and electrical conductors and severe phase separation occurs during the cooling process. Following a suggestion by Whitecross et al we have made up a series of salt solutions containing a small amount of graphite to improve the sample conductivity. In addition, we have incorporated a polymer to ensure the formation of microcrystalline ice and a consequent homogenity of salt dispersion within the frozen matrix. The mixtures have been used to standardize the analytical procedures applied to frozen hydrated bulk specimens based on the peak/background analytical method and to measure the absolute concentration of elements in developing roots.

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