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

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.

Stabilizing superconductivity of ternary metal pentahydride $$\hbox {CaCH}_{{5}}$$ via electronic topological transitions under high pressure from first principles evolutionary algorithm

“…The stable structure of the Pm and Cmcm structures can be considered from a characteristic bonding through a uniform electron gas of the same density. We show here that the electron localization function (ELF) 31 can be used to analyze the stability of high pressure structure as has been demonstrated in several materials 15 , 32 – 37 . First of all, we can observe the electrons distribution in the Pm structure at 50 GPa, which is plotted in the (010) plane (Fig.…”

“…Therefore, studying the Fermi surface plays a critical role for superconductivity 41 , 42 . Regarding the Fermi surface, the characteristics of the Fermi surface have been successfully determined for several materials 15 , 37 , 48 , 49 . Therefore, in this work, the and its Fermi surface are theoretically studied at a pressure of 450 GPa.…”

“…As a possible cause of this, one might think of the quantum effects. This because the quantum effects are important for the structural stabilities of materials with high EPC constants 17 , 37 , 52 such as 17 , 37 , and 52 , it is possible that EPC can destabilize quantum effects. For this particular case, it should be mentioned that the Cmcm structure is a dynamically unstable structure at the high-pressure limit (400 GPa).…”

Semiconducting phase of hafnium dioxide under high pressure: a theoretical studied by quasi-particle GW calculations

“…The possibility of finding an electron in the neighboring space of HfO 2 can be measured by the electron localization function (ELF) [41], as reported in Figure 2, where the structure of HfO 2 is presented as shown in Figure 2 (a). The tendency of ELF in HfO 2 is described by the uniform distribution of electron gas with the same density [31,32,42,43,44,45,46]. For the P4/nmm structure, the calculated ELF reveals a set of chemical bonding at the pressure of 150 GPa.…”

Effect of substitution on the superconducting phase of transition metal dichalcogenide Nb(Se$$_{x}$$S$$_{1-x}$$)$$_{2}$$ van der Waals layered structure

“…We further determined the electron localization function (ELF) and the projected crystal orbital Hamilton populations (pCOHP) method 40 , as previously demonstrated on several materials 33 – 35 , 41 , 42 , of Nb(Se S ) . Here, a uniform electron gas of the same density describes the characteristics of the chemical bonding.…”