Superconducting water derivatives of Sr 2 Ca n−1 Cu n O 2+2n-δ ( n  = 2–4) high- T c superconductors

Organic molecule intercalation sites in Sr2CaCu2Oy superconductor

“…The 0 (Sr) 212 crystal was assumed to be stacks of SrO-SrO-CuO 2 -Ca-CuO 2 -SrO-SrO layers along the c-axis, which was a half unit cell with extra two SrO layers attached on the top and the bottom. Cell parameters of a = b = 3.826 Å, c = 12.70 Å 20 were used from X-ray diffraction (XRD) analysis. 1,33,34 Secondly, H 2 O molecules were intercalated into the SrO-SrO layers (2.45 Å) in the 0 (Sr) 212 crystal.…”

“…This assumption may break the symmetry of 0 (Sr) 212 crystal, which has not been observed by XRD. 20 Thus, the present calculations must be improved in the future for obtaining the precise water molecule positions. However, it is meaningful to reproduce the c-parameter elongation upon the water molecule intercalation between SrO layers in a 0 (Sr) 212 crystal to form the derivative phase.…”

“…After the water (and/or organic molecule) intercalation, both 0 (Sr) 223 and 0 (Ba) 223 exhibited enhancement of irre-Honoring Dr. Mrityunjay Singh versibility field (H irr ) and "peak effect" in critical current density (J c ) properties. [17][18][19][20] When the water intercalate, T c for 0 (Ba) 223 was decreased from 127 to 90 K, while 0 (Sr) 223 showed no significant change in T c . 21 From these unique phenomena, 0 (Sr) 223 draws attention of researchers.…”

Enhanced magnetic irreversibility characteristics by expansion of blocking block for Sr2Ca2Cu3O8−δhigh-Tcsuperconductor

“…1 for the schematic illustrations of crystal structures) and by 2.7 Å for the Ba-based phase. In the former case, T c remains constant at 105 K, 16) while in the latter case, the T c of 126 K for the as-HP-synthesized zero phase decreases to 90 K upon water intercalation. 6) In this latter case, on the basis of the results of a comprehensive chemical analysis, it seems that, upon phase transition, not only neutral water molecules but also positively charged protons and=or carbonate species are intercalated such that the average valence of copper and accordingly, the hole concentration change.…”

“…For Ba-based zero phases, phase transformation is extremely fast at room temperature, whereas for Sr-based zero phases, phase transformation occurs with a decent speed only at an elevated temperature (80 °C). 16) In both cases, the water-intercalation reaction is best controlled for the n = 3 phase. Upon water intercalation, the blocking block expands by 3.1 Å for the Sr-based phase (see Fig.…”