scholarly journals Route to high-$$T_{c}$$ superconductivity of $$\hbox {BC}_{{7}}$$ via strong bonding of boron–carbon compound at high pressure

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Prutthipong Tsuppayakorn-aek ◽  
Xiaoyong Yang ◽  
Prayoonsak Pluengphon ◽  
Wei Luo ◽  
Rajeev Ahuja ◽  
...  

Abstract We have analyzed the compositions of boron–carbon system, in which the $$\hbox {BC}_{{7}}$$ BC 7 compound is identified as structural stability at high pressure. The first-principles calculation is used to identify the phase diagram, electronic structure, and superconductivity of $$\hbox {BC}_{{7}}$$ BC 7 . Our results have demonstrated that the $$\hbox {BC}_{{7}}$$ BC 7 is thermodynamically stable in the diamond-like $$P{\bar{4}}m2$$ P 4 ¯ m 2 structure at a pressure above 244 GPa, and under temperature also. Feature of chemical bonds between B and C atoms is presented using the electron localization function. The strong chemical bonds in diamond-like $$P{\bar{4}}m2$$ P 4 ¯ m 2 structure are covalent bonds, and it exhibits the s–p hybridization under the pressure compression. The Fermi surface shape displays the large sheet, indicating that the diamond-like $$P{\bar{4}}m2$$ P 4 ¯ m 2 phase can achieve a high superconducting transition temperature ($$\hbox {T}_{{c}}$$ T c ). The outstanding property of $$\hbox {BC}_{{7}}$$ BC 7 at 250 GPa has manifested very high-$$\hbox {T}_{{c}}$$ T c of superconductivity as 164 K, indicating that the carbon-rich system can induce the high-$$\hbox {T}_{{c}}$$ T c value as well.

2002 ◽  
Vol 58 (3) ◽  
pp. 457-462 ◽  
Author(s):  
F. Liebau ◽  
H. Küppers

To compare densities of inorganic high-pressure phases their molal volumes or specific gravities are usually employed, whereas for zeolites and other microporous materials the so-called framework density, FD, is applied. The definition of FD, which refers only to phases with three-dimensional tetrahedron frameworks, is extended to a `generalized framework density' d f, which is independent of the dimensionality of the framework and the coordination number(s) of the framework cations. In this paper the anion packing density, d ap, is introduced as a new quantity which is not only applicable to any inorganic phase but, in contrast to FD and d f, also allows quantitative comparisons to be made for crystalline inorganic phases of any kind. The anion packing density can readily be calculated if the volume and content of the unit cell and the radii of the anions of a phase are known. From d ap values calculated for high-pressure silica polymorphs studied under very high pressure, it is concluded that Shannon–Prewitt effective ionic radii do not sufficiently take into account the compressibility of the anions.


During the researches upon high-pressure explosions of carbonic oxide-air, hydrogen-air, etc., mixtures, which have been described in the previous papers of this series, a mass of data has been accumulated relating to the influence of density and temperature upon the internal energy of gases and the dissociation of steam and carbon dioxide. Some time ago, at Prof. Bone’s request, the author undertook a systematic survey of the data in question, and the present paper summarises some of the principal results thereof, which it is hoped will throw light upon problems interesting alike to chemists, physicists and internal-combustion engineers. The explosion method affords the only means known at present of determining the internal energies of gases at very high temperatures, and it has been used for this purpose for upwards of 50 years. Although by no means without difficulties, arising from uncertainties of some of the assumptions upon which it is based, yet, for want of a better, its results have been generally accepted as being at least provisionally valuable. Amongst the more recent investigations which have attracted attention in this connection should be mentioned those of Pier, Bjerrum, Siegel and Fenning, all of whom worked at low or medium pressures.


2010 ◽  
Vol 670 ◽  
pp. 21-27 ◽  
Author(s):  
Tatiana Prikhna ◽  
Wolfgang Gawalek ◽  
Yaroslav Savchuk ◽  
Athanasios G. Mamalis ◽  
Vasiliy Tkach ◽  
...  

The critical current density, jc, of high-pressure synthesized MgB2-based balk materials correlates with the amount and distribution of higher borides (MgB12) and Mg-B-O inclusions, which in tern correlates with the synthesis temperature and presence of additions (Ti, Ta, SiC). High-pressure-synthesized materials with near MgB12 composition of matrix exhibited superconducting transition temperature, Tc, of about 37 K, rather high jc (5∙105 and 103 A/cm2 in 0 T and 3.5 T, respectively, at 20 K) and doubled matrix microhardness: 25±1.1 GPa at 4.9 N –load as compared to materials with MgB2).


2012 ◽  
Vol 377 ◽  
pp. 012055 ◽  
Author(s):  
Y Mori ◽  
S Yokota ◽  
F Ono
Keyword(s):  

2021 ◽  
pp. 1-8
Author(s):  
Catherine A. M. Dillier ◽  
Erica D. Petersen ◽  
Thomas Sammet ◽  
Eric L. Petersen

Author(s):  
Rinke J. Wijngaarden ◽  
J. J. Scholtz ◽  
E. N. van Eenige ◽  
R. Griessen

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