Structure–property correlations in phase-pure B-doped Q-carbon high-temperature superconductor with a record Tc = 55 K

Nanoscale ◽  
2019 ◽  
Vol 11 (18) ◽  
pp. 9141-9154 ◽  
Author(s):  
Anagh Bhaumik ◽  
Jagdish Narayan

The discovery of record BCS Tc = 55 K superconductivity in phase-pure B-doped Q-carbon will provide the pathway to achieve room-temperature superconductivity.

1992 ◽  
Vol 7 (9) ◽  
pp. 2492-2494 ◽  
Author(s):  
Donald T. Morelli

The thermal conductivities of LaAlO3 and NdAlO3 have been measured for the first time between 10 and 300 K. These substrates can be classified as intermediate thermal conductors. The measured room temperature values of 9 W m−1 K−1 for LaAlO3 and 7.5 W m−1 K−1 for NdAlO3 are close to those predicted from the crystal structure of these materials, despite the fact that the crystals are twinned.


SPIN ◽  
2017 ◽  
Vol 07 (02) ◽  
pp. 1750006 ◽  
Author(s):  
Dennis M. Newns ◽  
Glenn J. Martyna ◽  
Chang C. Tsuei

Superconducting transition temperatures of 164 K in cuprate high temperature superconductors (HTS) and recently 200 K in H3S under high pressure encourage us to believe that room temperature superconductivity (RTS) might be possible. In considering paths to RTS, we contrast conventional (BCS) SC, such as probably manifested by H3S, with the unconventional superconductivity (SC) in the cuprate HTS family. Turning to SC models, we show that in the presence of one or more van Hove singularities (vHs) near the Fermi level, SC mediated by classical phonons ([Formula: see text]phonon frequency) can occur. The phonon frequency in the standard [Formula: see text] formula is replaced by an electronic cutoff, enabling a much higher [Formula: see text] independent of phonon frequency. The resulting [Formula: see text] and isotope shift plot versus doping strongly resembles that seen experimentally in HTS. A more detailed theory of HTS, which involves mediation by classical phonons, satisfactorily reproduces the chief anomalous features characteristic of these materials. We propose that, while a path to RTS through an H3S-like scenario via strongly-coupled ultra-high frequency phonons is attractive, features perhaps unavailable at ordinary pressures, a route involving SC mediated by classical phonons which can be low frequency may be found.


2004 ◽  
Vol 17 (5) ◽  
pp. S324-S327 ◽  
Author(s):  
M I Faley ◽  
K Pratt ◽  
R Reineman ◽  
D Schurig ◽  
S Gott ◽  
...  

2009 ◽  
Vol 23 (04) ◽  
pp. 597-613 ◽  
Author(s):  
VALERY M. IOFFE

The basic idea is that we try to find some materials in which bosonic ions with sufficiently small effective mass are used as charge carriers instead of Cooper's pairs in order to provide high temperature ionic superconductivity. Ionic crystals LiCl , LiF , LiBr and LiI were considered with lithium isotope Li 6. Calculations show that Bose condensation temperature for lithium ions in these crystals is of the order of 10-34–10-43 K. If, however, the crystal is compressed so that the wave functions of neighboring lithium ions are sufficiently overlapped, then Bose-condensation temperature of Li 6-ions can be increased significantly. Our estimates show that by compressing the crystals by 20–22% in all three directions, one can raise the Bose-condensation temperature in all crystals considered to above room temperature. To realize materials with room temperature superconductivity in practice, the use of molecular beam epitaxy is proposed for the formation of heterostructures from thin and thick layers of thoughtfully chosen composition.


2013 ◽  
Vol 58 (3) ◽  
pp. 673-676
Author(s):  
D. Guney

Abstract High temperature MgO-ZrO2 insulation coatings were grown on long-length Stainless-Steel (SS) tapes by reel-to-reel sol-gel method for applications of High Temperature Superconductor/Low Temperature Superconductor (HTS/LTS) coils and magnets. The residual stresses were investigated analytically at various temperature ranges, 580°C to 25°C (room temperature) and -196°C (liquid helium temperature), and 630°C to 25°C and -196°C for different thicknesses to be 13, 12, and 7 μm. The maximum stress values were obtained to be 1.92 GPa in tension for SS substrate with the 13 μm coating and -2.42 GPa in compression for the 7 μm MgO-ZrO2 coating in the temperature range between 630°C and liquid helium temperature. The surface morphologies and microstructure of sample were also characterized using a scanning electron microscope (SEM). SEM observations revealed that MgO-ZrO2 coatings have a mosaic like crack structure.


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