Li2xBC3: Prediction of a second MgB2-class high-temperature superconductor

Yundi Quan; Warren E. Pickett

doi:10.1103/PhysRevB.102.144504

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Li2xBC3: Prediction of a second MgB2-class high-temperature superconductor

Yundi Quan, Warren E. Pickett

DOI 10.1103/PhysRevB.102.144504 · Physical Review B

T1

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Abstract

Recent synthesis of Li2xBC3, pseudoisostructural to MgB2, has been reported, with control of doping level by concentration x of Li. Density-functional calculations based on the virtual crystal approximation confirm metalization over a wide range of Li concentration but predict regions of structural instability. The electron-phonon coupling strength and superconducting critical temperature Tc around x=0.5 is found to be comparable to that in MgB2, but of different character, accounting for the unexpected result that a stronger bond-stretch mode and a higher B–C Eg mode frequency results in little increase in Tc. The B–C honeycomb layer contributes strong σ-bonding (px,py) cylinders similar to MgB2,while the corresponding C–C states lie well below the Fermi level and are dead” for coupling. However, the π-bonding (pz) states on the B–C/C–C layer provide a large Fermi-level density of states and weak coupling that moderates the coupling strength and thereby Tc.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Li2xBC3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	40	Pressure not reported	unknown
LiBC3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	40	Pressure not reported	unknown
MgB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	40	Pressure not reported	unknown
Li1-xBC Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	75	Pressure not reported	unknown
Li2B3C Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	37	Pressure not reported	unknown
Li4B5C3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	17	Pressure not reported	unknown
Li3B4C2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	40	Pressure not reported	unknown
LiB2C2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	40	Pressure not reported	unknown