LOW TEMPERATURE RESISTIVITY OF THE TRANSITION ELEMENTS: RUTHENIUM AND OSMIUM

Experimental values are reported for the electrical resistivity of ruthenium and osmium from 2 to 300 °K and for the thermal resistivity from 2 to 140° K. The samples were produced by arc-melting pressed pellets of metallic powder in an inert gas atmosphere. Two osmium samples and one ruthenium sample showed a satisfactorily low residual electrical resistance. By grinding these rods to a regular shape, absolute values of resistivity were obtained and the impurity and thermal components of resistivity derived; at room temperature (295 °K) we deduce that for ideally pure Os, [Formula: see text] and for ideally pure ruthenium [Formula: see text]. The temperature dependence of the resistivity was markedly different for another ruthenium sample but it seems likely that this was not representative of pure h.c.p. ruthenium.

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LOW TEMPERATURE RESISTIVITY OF TRANSITION ELEMENTS: VANADIUM, NIOBIUM, AND HAFNIUM

Canadian Journal of Physics ◽

10.1139/p57-098 ◽

1957 ◽

Vol 35 (8) ◽

pp. 892-900 ◽

Cited By ~ 36

Author(s):

G. K. White ◽

S. B. Woods

Keyword(s):

Thermal Conductivity ◽

Electrical Conductivity ◽

Electrical Resistivity ◽

Electrical Resistance ◽

Thermal Resistivity ◽

Superconducting Transition ◽

Transition Elements ◽

Pure Niobium ◽

Temperature Resistivity ◽

The Ideal

Measurements of the thermal conductivity from 2° to 90 ° K. and electrical conductivity from 2° to 300 ° K. are reported for vanadium, niobium, and hafnium. Although the vanadium and hafnium are not as pure as we might wish, measurements on these metals and on niobium allow a tabulation of the "ideal" electrical resistivity clue to thermal scattering for these elements from 300 ° K. down to about 20 ° K. Ice-point values of the "ideal" electrical resistivity are 18.3 μΩ-cm. for vanadium, 13.5 μΩ-cm. for niobium, and 29.4 μΩ-cm. for hafnium. Values for the "ideal" thermal resistivity of vanadium and niobium are deduced from the experimental results although for vanadium and more particularly for hafnium, higher purity specimens are required before a very reliable study of "ideal" thermal resistivity can be made. For the highly ductile pure niobium, the superconducting transition temperature, as determined from electrical resistance, appears to be close to 9.2 ° K.

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LOW TEMPERATURE RESISTIVITY OF THE TRANSITION ELEMENTS: COBALT, TUNGSTEN, AND RHENIUM

Canadian Journal of Physics ◽

10.1139/p57-070 ◽

1957 ◽

Vol 35 (5) ◽

pp. 656-665 ◽

Cited By ~ 28

Author(s):

G. K. White ◽

S. B. Woods

Keyword(s):

Electrical Resistivity ◽

Low Temperature ◽

Thermal Resistance ◽

High Purity ◽

Thermal Resistivity ◽

Superconducting Transition ◽

Transition Elements ◽

Experimental Values ◽

Thermal Vibrations ◽

Temperature Resistivity

Experimental values are reported for the electrical resistivity from 1.5° to 300° K. and for the thermal resistivity from 2° to 120° K. of high purity cobalt, tungsten, and rhenium. The temperature variation of the components of the electrical and of the thermal resistance due to scattering by thermal vibrations is deduced and the possible evidence for the importance of s–d transitions is discussed briefly. The temperature of the superconducting transition in samples of rhenium is found to be close to 1.70° K., the value reported by Hulm (1954).

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Computational Intelligence Approach for Estimating Superconducting Transition Temperature of Disordered MgB2Superconductors Using Room Temperature Resistivity

Applied Computational Intelligence and Soft Computing ◽

10.1155/2016/1709827 ◽

2016 ◽

Vol 2016 ◽

pp. 1-7 ◽

Cited By ~ 1

Author(s):

Taoreed O. Owolabi ◽

Kabiru O. Akande ◽

Sunday O. Olatunji

Keyword(s):

Transition Temperature ◽

Superconducting Transition Temperature ◽

Room Temperature ◽

Optimization Technique ◽

Support Vector ◽

Measuring Instruments ◽

Room Temperature Resistivity ◽

Superconducting Transition ◽

Experimental Values ◽

Temperature Resistivity

Doping and fabrication conditions bring about disorder in MgB2superconductor and further influence its room temperature resistivity as well as its superconducting transition temperature (TC). Existence of a model that directly estimatesTCof any doped MgB2superconductor from the room temperature resistivity would have immense significance since room temperature resistivity is easily measured using conventional resistivity measuring instrument and the experimental measurement ofTCwastes valuable resources and is confined to low temperature regime. This work develops a model, superconducting transition temperature estimator (STTE), that directly estimatesTCof disordered MgB2superconductors using room temperature resistivity as input to the model. STTE was developed through training and testing support vector regression (SVR) with ten experimental values of room temperature resistivity and their correspondingTCusing the best performance parameters obtained through test-set cross validation optimization technique. The developed STTE was used to estimateTCof different disordered MgB2superconductors and the obtained results show excellent agreement with the reported experimental data. STTE can therefore be incorporated into resistivity measuring instruments for quick and direct estimation ofTCof disordered MgB2superconductors with high degree of accuracy.

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Влияние атомов замещения и внедрения на магнитные свойства соединения Sm-=SUB=-2-=/SUB=-Fe-=SUB=-17-=/SUB=-

Письма в журнал технической физики ◽

10.21883/pjtf.2021.12.51058.18731 ◽

2021 ◽

Vol 47 (12) ◽

pp. 6

Author(s):

С.В. Веселова ◽

И.С. Терёшина ◽

В.Н. Вербецкий ◽

К.В. Захаров ◽

В.Б. Тверской ◽

...

Keyword(s):

Crystal Structure ◽

Curie Temperature ◽

Saturation Magnetization ◽

Room Temperature ◽

Magnetic Hysteresis ◽

Inert Gas ◽

Magnetic Characteristics ◽

Induction Melting ◽

Gas Atmosphere ◽

Hysteresis Properties

(Sm1-xRx)2Fe17 (R = Ho, Er) alloys with х = 0.1, 0.2 and 0.4 were prepared by induction melting under inert gas atmosphere. The structure and magnetic hysteresis properties of both the initial compositions and hydrides based on them are investigated. It was found that (Sm1-xRx)2Fe17Нy hydrides like the parent compounds have a rhombohedral Th2Zn17-type of crystal structure (sp.gr. R m). Hydrogenation results in a significant increase in the Curie temperature and saturation magnetization at room temperature. Compositions with potentially high magnetic characteristics have been determined.

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Electrical resistance of a carbon nanotube bundle

Journal of Materials Research ◽

10.1557/jmr.1994.0927 ◽

1994 ◽

Vol 9 (4) ◽

pp. 927-932 ◽

Cited By ~ 127

Author(s):

L. Langer ◽

L. Stockman ◽

J. P. Heremans ◽

V. Bayot ◽

C. H. Olk ◽

...

Keyword(s):

Magnetic Field ◽

Carbon Nanotube ◽

Electrical Resistance ◽

Room Temperature ◽

Dimensional Structure ◽

One Dimensional ◽

Similar Band ◽

Nanotube Bundle ◽

Temperature Resistivity ◽

Crystalline Graphite

The first direct electrical resistance measurements performed on a single carbon nanotube bundle from room temperature down to 0.3 K and in magnetic fields up to 14 T are reported. From the temperature dependence of the resistance above 2 K, it is shown that some nanotubes exhibit a semimetallic behavior akin to rolled graphene sheets with a similar band structure, except that the band overlap, Δ ≈ 3.7 meV, is about 10 times smaller than for crystalline graphite. In contrast to graphite which shows a constant low-temperature resistivity, the nanotubes exhibit a striking increase of the resistance followed by a broad maximum at very low temperatures. A magnetic field applied perpendicular to the sample axis decreases the resistance. Above 1 K, this behavior is consistent with the formation of Landau levels. At lower temperatures, the resistance shows an unexpected drop at a critical temperature which increases linearly with magnetic field. These striking features could be related to the unique quasi-one-dimensional structure of the carbon nanotubes.

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β-Amino functionalization of cinnamic Weinreb amides in ionic liquid

Beilstein Journal of Organic Chemistry ◽

10.3762/bjoc.12.231 ◽

2016 ◽

Vol 12 ◽

pp. 2372-2377 ◽

Cited By ~ 1

Author(s):

Yi-Ning Wang ◽

Guo-Xiang Sun ◽

Gang Qi

Keyword(s):

Ionic Liquid ◽

Room Temperature ◽

Metal Catalysts ◽

Inert Gas ◽

One Pot ◽

Weinreb Amides ◽

One Pot Synthesis ◽

Gas Atmosphere ◽

Amino Functionalization ◽

Reaction Media

2-Ns-Protected β-amino Weinreb amides were synthesized by aminochlorination of α,β-unsaturated Weinreb amides in an ionic liquid, 1-n-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([BMIM][NTf2]). Processed without the use of metal catalysts or the need of an inert gas atmosphere, the presented process can be readily performed as a one-pot synthesis at room temperature. Moreover, the preparation has the distinct advantages of the use of 2-NsNCl2 as an inexpensive and stable nitrogen/halogen source and the ionic liquid as a recyclable reaction media. Nine examples were examined, and modest to good isolated chemical yields (40–83%) were obtained.

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Silicon Carbide Die Attach Scheme for 500°C Operation

MRS Proceedings ◽

10.1557/proc-622-t8.10.1 ◽

2000 ◽

Vol 622 ◽

Cited By ~ 11

Author(s):

Liang-Yu Chen ◽

Gary W. Hunter ◽

Philip G. Neudeck

Keyword(s):

Silicon Carbide ◽

High Temperature ◽

Electrical Resistance ◽

Room Temperature ◽

Semiconductor Devices ◽

Single Crystal Silicon ◽

Film Material ◽

Crystal Silicon ◽

Pure Alumina ◽

Die Attach

ABSTRACTSingle crystal silicon carbide (SiC) has such excellent physical, chemical, and electronic properties that SiC based semiconductor electronics can operate at temperatures in excess of 600°C well beyond the high temperature limit for Si based semiconductor devices. SiC semiconductor devices have been demonstrated to be operable at temperatures as high as 600°C, but only in a probe-station environment partially because suitable packaging technology for high temperature (500°C and beyond) devices is still in development. One of the core technologies necessary for high temperature electronic packaging is semiconductor die-attach with low and stable electrical resistance. This paper discusses a low resistance die-attach method and the results of testing carried out at both room temperature and 500°C in air. A 1 mm2 SiC Schottky diode die was attached to aluminum nitride (AlN) and 96% pure alumina ceramic substrates using precious metal based thick-film material. The attached test die using this scheme survived both electronically and mechanically performance and stability tests at 500°C in oxidizing environment of air for 550 hours. The upper limit of electrical resistance of the die-attach interface estimated by forward I-V curves of an attached diode before and during heat treatment indicated stable and low attach-resistance at both room-temperature and 500°C over the entire 550 hours test period. The future durability tests are also discussed.

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Piezoresistivity and Electrical Resistance Relaxation of Polyisoprene Nanostructured Carbon Allotrope Hybrid Composites

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1117.52 ◽

2015 ◽

Vol 1117 ◽

pp. 52-55

Author(s):

Artis Linarts ◽

Maris Knite

Keyword(s):

Electrical Resistance ◽

Room Temperature ◽

Constant Pressure ◽

Hybrid Composites ◽

Conductive Filler ◽

Force Sensor ◽

Filler Concentration ◽

Nanostructured Carbon ◽

Carbon Allotrope ◽

Resistance Relaxation

Polymer conductive filler composites are believed to be promising materials for flexible force sensor manufacture. Polyisoprene various carbon allotrope hybrid composites were made and their piezoresistive properties depending on the two type’s filler concentration and their ratio have been determined. Electrical resistance relaxations of hybrid composites at constant pressure in room temperature were determined as well. Experimental data of resistance relaxation was analyzed and fitted similarly to stress relaxation of polymers at constant pressure.

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Influence of Modulation Wavelength Induced Order on the Physical Properties of Nb/Rare Earth Superlattices

MRS Proceedings ◽

10.1557/proc-37-523 ◽

1984 ◽

Vol 37 ◽

Author(s):

L. H. Greene ◽

W. L. Feldmann ◽

J. M. Rowell ◽

B. Batlogg ◽

R. Hull ◽

...

Keyword(s):

Rare Earth ◽

Room Temperature ◽

Room Temperature Resistivity ◽

Residual Resistance ◽

Sapphire Substrates ◽

Transmission Electron ◽

Sputter Deposited ◽

Residual Resistance Ratio ◽

Temperature Resistivity ◽

Modulation Wavelength

AbstractWe report the observation of a higher degree of preferred crystalline orientation in Nb/rare earth superlattices for modulation wavelengths in the range of 200 Å to 500 Å than that exhibited by single component films. All films and multilayers are sputter deposited onto room temperature sapphire substrates. Electronic transport measurements also show that the residual resistance ratio is higher and the room temperature resistivity is lower than for multilayers of either greater or lower periodicities. Transmission electron micrographs (TEM) showing excellent layering, grain size comparable to the layer thickness, and evidence of some degree of epitaxy are presented.

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