High-temperature superconductivity in SrB3C3 and BaB3C3 predicted f

Prediction of novel boron–carbon based clathrates

“…After the substitution of Ba for Sr, the T c values can be increased from 40 to 43 K due to phonon softening. 21 Besides these bivalent guest atoms, clathrate trapped trivalent La 3+ and Sc 3+ ions are also evaluated as stable compounds. 22,23 La 3+ [B 3 C 3 ] 3− is a semiconductor with an indirect band gap of near 1.3 eV.…”

High- Tc superconductivity in doped boron-carbon clathrates

“…Based on a full scan of the periodic table, we find that only five elements (Ca, Sr, Y, Ba, and La) form stable X B 3 C 3 compounds at ambient or moderate pressure. Two of them (La, Sr) have already been experimentally synthesized [23,31,33]. While the superconducting T c of ternary X B 3 C 3 compounds are comparable to those of MgB 2 , the best conventional superconductor known so far, ordered alloys XY B 6 C 6 containing mono-and divalent elements are, instead, expected to yield a substantial improvement, reaching T c 's as high as 77 K. KCaB 6 C 6 and NaSrB 6 C 6 , where a high T c coexists with a relatively moderate stabilization pressure (20 and 18 GPa), represent very promising combinations of elements among all sameand inter-row combinations considered here.…”

“…While the empty B-C cage is dynamically and thermodynamically unstable at ambient pressure, a few X B 3 C 3 compounds can be stabilized under pressure and exhibit a variety of attractive physical properties, such as superhardness (La) and ferroelectricity (Sc) [23,30,31]. Among them SrB 3 C 3 , which forms in diamond anvil cells at high pressure (57 GPa) but survives close to room pressure, has been theoretically predicted to superconduct below 40 K [32,33], a T c close to the current record for ambient-pressure conventional superconductivity, held by magnesium diboride (MgB 2 ) [13]. Given the extreme versatility of cagelike structures observed in superhydrides, we expect that a suitable choice of the guest atom is likely to attain even higher T c .…”

High-T$_c$ Superconductivity in doped boron-carbon clathrates

“…Two of them (La, Sr) have already been experimentally synthesized. 23,31,32 While the superconducting T c of ternary XB 3 C 3 compounds are comparable to those of MgB 2 , the best conventional superconductor known so far, ordered alloys XY B 6 C 6 containing mono-and divalent elements are, instead, expected to yield a substantial improvement, reaching T c 's as high as 77 K. KCaB 6 C 6 , where a high T c ; cohexists with a relatively moderate stabilization pressure (18 GPa), represents the most promising combination of elements among those considered here. A careful tuning of dopants and compositions may further increase T c and/or reduce stabilization pressure.…”

“…The empty B-C cage is dynamically and thermodynamically unstable at ambient pressure; however, a few XB 3 C 3 compounds can be stabilized under pressure and exhibit a variety of attractive physical properties, such as superhardness (La) and ferroelectricity (Sc). 23,[30][31][32] Figure 1. Crystal structure of XB3C3.…”