Consecutive inert and oxygen atmosphere sintering in the synthesis of LaBa2Cu3Oy with T(R = 0)>90 K

1989 ◽  
Vol 4 (5) ◽  
pp. 1111-1115 ◽  
Author(s):  
M. H. Ghandehari ◽  
S. G. Brass
Keyword(s):  
Crystal Lattice ◽  
Liquid Nitrogen ◽  
Boiling Point ◽  
Inert Atmosphere ◽  
Oxygen Atmosphere ◽  
Processed Material ◽  
Zero Resistance ◽  
Processing Steps

Combinations of inert atmosphere sintering and oxygen atmosphere sintering have previously been reported as necessary for the synthesis of LaBa2Cu3Oy superconductors which achieve zero resistance at temperatures above 90 K. Sintering under oxygen atmosphere only is known to produce La(1+x)Ba(2−x)Cu3Oy, in which La is substituted for Ba in the crystal lattice. The latter substituted compounds achieve zero resistance at temperatures well below the boiling point of liquid nitrogen. In this work, we show that during the initial inert atmosphere sintering step, LaBa2Cu3Oy powder decomposes, in part, into several intermediate compounds. These compounds are then recombined in the subsequent oxygen atmosphere sintering step to form LaBa2Cu3Oy, which achieves zero resistance at temperatures above 90 K. We propose that the net effect of these two processing steps is to inhibit the substitution of La for Ba in the lattice of the fully processed material.

STUDY OF THE DEPENDENCE OF HIGH Tc ON VARIOUS SINTERING TEMPERATURES FOR Bi-Pb-Sr-Ca-Cu-O SUPERCONDUCTORS

1991 ◽  
Vol 05 (24n25) ◽  
pp. 1635-1638
Author(s):  
S.M. M.R. NAQVI ◽  
A.A. QIDWAI ◽  
S.M. ZIA-UL-HAQUE ◽  
FIROZ AHMAD ◽  
S.D.H. RIZVI ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Liquid Nitrogen ◽  
X Ray Diffraction ◽  
High Tc ◽  
X Ray ◽  
Resistivity Measurements ◽  
Zero Resistance

Bi1.7-Pb0.3-Sr2-Ca2-Cu3-Ox superconducting samples were prepared at 855°C, 862 C, 870 C, and 882 C sintering temperatures respectively. All samples were sintered for 120 hours. The samples were then quenched in liquid nitrogen. The electrical resistivity measurements showed that the samples sintered at 870° C had the best Tc. For these samples the Tc onset was around 120 K and the zero resistance was obtained at 108 K. X-ray diffraction studies showed that the samples were multiphased.

Understanding Thermal Drift in Liquid Nitrogen Loads Used for Radiometric Calibration in the Field

2014 ◽  
Vol 31 (3) ◽  
pp. 647-655 ◽  
Author(s):  
Scott N. Paine ◽  
David D. Turner ◽  
Nils Küchler
Keyword(s):  
Liquid Nitrogen ◽  
Boiling Point ◽  
Volume Fraction ◽  
Radiometric Calibration ◽  
Initial Boiling Point ◽  
Nitrogen Loads ◽  
Outdoor Environments ◽  
Infrared Wavelengths ◽  
Simulated Wind ◽  
Liquid Nitrogen Bath

Abstract An absorbing load in a liquid nitrogen bath is commonly used as a radiance standard for calibrating radiometers operating at microwave to infrared wavelengths. It is generally assumed that the physical temperature of the load is stable and equal to the boiling point temperature of pure N2 at the ambient atmospheric pressure. However, this assumption will fail to hold when air movement, as encountered in outdoor environments, allows O2 gas to condense into the bath. Under typical conditions, initial boiling point drift rates of order 25 mK min−1 can occur, and the boiling point of a bath maintained by repeated refilling with pure N2 can eventually shift by approximately 2 K. Laboratory bench tests of a liquid nitrogen bath under simulated wind conditions are presented together with an example of an outdoor radiometer calibration that demonstrates the effect, and the physical processes involved are explained in detail. A key finding is that in windy conditions, changes in O2 volume fraction are related accurately to fractional changes in bath volume due to boiloff, independent of wind speed. This relation can be exploited to ensure that calibration errors due to O2 contamination remain within predictable bounds.

Study on Morphology of Electrospun SiOC Fibers

2015 ◽  
Vol 1123 ◽  
pp. 223-226
Author(s):  
Jan Setiawan ◽  
Slamet Pribadi ◽  
Pranjono ◽  
Suhardjo Poertadji ◽  
Sigit
Keyword(s):  
Applied Voltage ◽  
Thermal Process ◽  
Inert Atmosphere ◽  
Solvent Evaporation ◽  
Silicon Oxycarbide ◽  
Oxygen Atmosphere ◽  
Curing Process

Polycarbosilane (PCS) solution was used to form PCS fibers by electrospinning and curing them by thermal process. The cured PCS fibers were then pyrolized under inert atmosphere to obtain silicon oxycarbide (SiOC) fibers. The PCS solution contained 1.2 g/mL PCS with 30% N, N-dimethylformamide (DMF)/70% toluene. The needle inner diameters used for spinning were 0.5 and 0.3 mm and variation for the applied voltage were 10, 12 and 14 kV. The electrospun PCS fibers were cured at 200°C in oxygen atmosphere for 1 hour and then pyrolyzed at 1000°C in inert atmosphere for 1 hour. Nonwoven SiOC fibers diameter ranging between 3 to 8 µm were analyzed by SEM and EDS. The oxygen embodied on the surface of cured PCS fibers arising during the curing process resulted in the SiOC fibers with larger diameters. Rapid solvent evaporation during the pyrolysis caused the SiOC fibers to have ribbon-shapes.

Effect of Thermal Treatment under Oxygen Atmosphere on the Superconducting Properties of RuSr2GdCu2O8

2006 ◽  
Vol 530-531 ◽  
pp. 550-556 ◽  
Author(s):  
Juliana Maria de Albuquerque Gimenez ◽  
Carlos Roberto Grandini ◽  
M.S. Góes ◽  
A.R. Jurelo ◽  
R. Dobrzanski
Keyword(s):  
Previous Treatment ◽  
Inert Atmosphere ◽  
Oxygen Atmosphere ◽  
Oxygen Flow ◽  
Thermal Treatments ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
Mechanical Spectroscopy ◽  
Preparation Conditions ◽  
Flow Through

The discovery of the spatial uniform coexistence of superconductivity and ferromagnetism in rutheno-cuprates, RuSr2GdCu2O8 (Ru-1212), has spurred an extraordinary development in the study of the competition between magnetism and superconductivity. However, several points of their preparation process and characterization that determine their superconductive behavior are still obscure. The improvement of sample preparation conditions involves some thermal treatments in inert atmosphere. The first treatment results in the immediate formation of Sr2GdRuO6. Using the CuO composition as a precursor, we produced Ru-1212. To turn it metallic and superconductor, besides the previous treatment, a final sinterization is carried out in oxygen flow for several days. Three Ru-1212 samples were produced by varying the last sinterization time (two, four, and six days under oxygen flow). Through measurements of x-ray diffraction, scanning electron microscopy, differential thermal analysis, magnetic susceptibility and mechanical spectroscopy, it was studied the influence of the treatments under oxygen atmosphere on the structural and superconducting properties of the material.

scholarly journals Reactions of MoCl5 and MoO2Cl2 with 4-Phenylimidazole-2-Thiol and 2-Thiazoline-2-Thiol

2020 ◽  
Vol 36 (6) ◽  
pp. 1096-1102
Author(s):  
Deepika Rani ◽  
Gursharan Singh ◽  
Seema Sharma
Keyword(s):  
Liquid Nitrogen ◽  
1H Nmr ◽  
Elemental Analysis ◽  
Room Temperature ◽  
Inert Atmosphere ◽  
Molar Ratios ◽  
Vacuum Line

Reactions of MoCl5/MoO2Cl2 with 4-phenylimidazole-2-thiol/2-thiazoline-2-thiol in CH3CNsolvent in 1:1/1:2 molar ratios have been carried out at room temperature. Products obtained MoCl3(C9H7N2S)(CH3CN), [1];MoCl2(C9H7N2S)(CH3CN), [2]; Mo2OCl4(C9H8N2S)2, [3] and Mo4O2Cl12(C9H7N2S)4, [4]; MoO2Cl3(C3H5NS2)2, [5] and Mo2O4Cl3(C3H5NS2)2, [6] have been analyzed and characterizedby elemental analysis, FTIR, 1H NMR and LC-MS techniques. Compounds being moisture and air sensitive, these have been prepared in inert atmosphere using vacuum line and liquid nitrogen cooled traps. Fragments obtained in LC-MS spectra support the formulae derived.

scholarly journals Reactions of MoCl5 and MoO2Cl2 with 4-Phenylimidazole-2-thiol and 2-Thiazoline-2-thiol

2020 ◽  
Vol 36 (6) ◽  
pp. 1096-1102
Author(s):  
Deepika Rani
Keyword(s):  
Liquid Nitrogen ◽  
1H Nmr ◽  
Elemental Analysis ◽  
Room Temperature ◽  
Inert Atmosphere ◽  
Molar Ratios ◽  
Vacuum Line

Reactions of MoCl5/MoO2Cl2 with 4-phenylimidazole-2-thiol/2-thiazoline-2-thiol in CH3CN solvent in 1:1/1:2 molar ratios have been carried out at room temperature. Products obtained MoCl3(C9H7N2S)(CH3CN),[1]; MoCl2(C9H7N2S)(CH3CN), [2]; Mo2OCl4(C9H8N2S)2, [3] and Mo4O2Cl12(C9H7N2S)4, [4]; MoO2Cl3(C3H5NS2)2, [5] and Mo2O4Cl3(C3H5NS2)2, [6] have been analyzed and characterized by elemental analysis, FTIR, 1H NMR and LC-MS techniques. Compounds being moisture and air sensitive, these have been prepared in inert atmosphere using vacuum line and liquid nitrogen cooled traps. Fragments obtained in LC-MS spectra support the formulae derived.

scholarly journals Microstructure Evolution of Mg-2Y-0.6Nd-0.6Zr Alloy Rolled at Room and Liquid Nitrogen Temperature

2021 ◽  
Author(s):  
Yun Tan ◽  
Wei Li ◽  
Aiwen Li ◽  
Xiaofang Shi
Keyword(s):  
Liquid Nitrogen ◽  
Microstructure Evolution ◽  
Room Temperature ◽  
Extrusion Direction ◽  
Liquid Nitrogen Temperature ◽  
Processed Material ◽  
Cold Rolled ◽  
Room Temperature Rolling ◽  
Lower Temperature ◽  
Low Temperature Rolling

Abstract The microstructure evolution, texture, mechanical behavior and twin deformation of the ECAPed Mg-2Y-0.6Nd-0.6Zr alloy at liquid nitrogen temperature were investigated by rolling samples. The ECAP processed material appeared the texture of 45 ° to the extrusion direction and its yield strength reached 93.6 MPa. The results showed that cryorolling encourages twinning in Mg-2Y-0.6Nd-0.6Zr alloy, enhancing the tensile strength and texture. Activation of {10-12} twinning during rolling was found to be more pronounced in the cryorolled samples than in the cold rolled samples owing to a lower temperature. As a result, the cryorolled samples had more twins than and cold rolled ones, the proportion of twin areas of room temperature rolling and ultra-low temperature rolling were: 2.445% and 4.234%.

scholarly journals Quantification of the effect of texture on the magnetization behavior

2018 ◽  
Vol 69 (6) ◽  
pp. 458-460
Author(s):  
Jürgen Schneider ◽  
Armin Franke ◽  
Anett Stöcker ◽  
Rudolf Kawalla
Keyword(s):  
Distribution Function ◽  
Orientation Distribution Function ◽  
Orientation Distribution ◽  
Texture Parameter ◽  
Electrical Steels ◽  
Processed Material ◽  
Euler Space ◽  
Processing Steps ◽  
Magnetization Behavior ◽  
Magnetization Behaviour

Abstract For electrical steels there is a need to describe the intensity of the present texture components in the finally processed material as well as after the various processing steps. Preferable texture components like the cube fibre texture will improve the magnetization behaviour. Furthermore, there is interplay between the various processing steps at fabrication on the resulting final texture in the fully processed material. A texture parameter A can be derived from the orientation distribution function (ODF) for arbitrary texture, which describes the texture for each texture components. Taking into account this fact, we used a so-called A-map. The A-map gives the value of A for each point in the Euler space for two fixed values (constants). This A-map may be used to estimate immediately the effect of a different resulting image of texture due to variation of the technology of fabrication of the material. Any increase of the intensity of texture within the area of the ODF, where the A-values are smaller than a certain value, results in improved magnetization behaviour. Within the paper some examples are given.

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