How Tc can go above 100 K in the YBCO family

Structural Phase of Y358 Superconductor Comparison with Y123

“…Two critical temperatures can be discerned from this plot: T C ≈ 94 K, associated to the Y123 phase, and T C ≈ 105 K, which we associate to the remaining phase, Y358, that is a T mid C (Y358) − T mid C (Y123) = 11 K in T C s difference, which is larger than the resolution of our thermometer. The T C (Y358) ≈ 105 K is in fact in good agreement with [5,6]. Note also that the ρ-T plot indicates an insulating character for the sample in 120-188 K range, whereas in the 95-115 K range a metal-like behavior, with dρ/dT = 0.032 m cm/K, is evident.…”

“…For example, density functional theory (DFT) calculations (based on the structure shown in Fig. 4) have also verified the suggested structure of Y358 compounds [6]. More specifically, these calculations showed that the hole concentration in the chains of Y123, Y247, Y124, and Y358 plays an important role in why Y358 and Y247 feature higher T C than the rest: the improvement in T C has been attributed to lower number of holes in the CuO chains of Y358 and Y247 relative to Y123 and Y124.…”

“…This result is in conflict with that of [5,6]. Since then, two more groups have attempted to characterize Y358 [8,9]; one obtaining lattice parameters similar to Y123 [7,8], while the other group has reported lattice parameters similar to those of [5,6], but with a different symmetry group [9].…”

Electronic structures of PrBa2Cu3O7, Pr2Ba4Cu7O15−y (y = 0, 1), and PrBa2Cu4O8 based on LSDA + U method

“…This comparison seems to be applicable for high-T c cuprates as it can explain the doping dependence of superconducting properties [31,32]. The obtained results show that the muffin-tin holes are reduced by 0.05 e in each site of Pr123 planes with respect to the Y123 system.…”

Fluorine Doping Effect in the New Superconducting Y<sub>3</sub>Ba<sub>5</sub>Cu<sub>8</sub>O<sub>y</sub> Compound

“…Y124 has one CuO double chain and one inequivalent plane. Y247 has one CuO chain, one CuO double chain and two in-equivalent CuO 2 planes [5]. More recently, Aliabadi et al [6] have reported a new superconductor Y 3 Ba 5 Cu 8 O 18 (Y358) of T c above 100 K with the same crystalline structure as that of Y123 but CuO 2 planes are increased to five and CuO chains are increased to three.…”