High-pressure study on Mo-stabilized Sr-based 123 compounds YSr2Cu2.8Mo0.2Oy and TbSr2Cu2.7Mo0.3Oy

Oxidation induced superconductivity and Mo/Cu charge equilibrium in Mo0.3Cu0.7Sr2ErCu2Oy

“…Site occupancy refinement for the AP sample indicates that the chemical substitution of the Mo ions for the Cu ions occurs in both Cu sites (Cu1 and Cu2). We have determined that the majority of the Mo (0.25(1), ∼83% of the total Mo content) substitution in this AP sample occurs for the copper in the chain sites (Cu1), which is in a good agreement with previous works [21,25]. No trace of Mo substitution at the Cu2 site is observed in the RT XRD/NPD joint refinement for the OA sample (Mo occupancy becomes negative when Mo is allowed to share the Cu2 site).…”

“…Recently, our work on Mo x Cu 1−x Sr 2 YCu 2 O y has revealed that full replacement of Mo for Cu in the chain site is not possible at ambient pressure [22]. SC (T C = 30 K) and magnetic ordering (T N = 5.4 K) has been found in Mo 0.3 Cu 0.7 Sr 2 TbCu 2 O y material [23][24][25]. Mo 0.3 Cu 0.7 Sr 2 TmCu 2 O y material shows an interesting spin glass to superconducting phase transformation following an oxidation reaction [26].…”

Synthesis and characterization of new cuprates

“…Hence, lead may exist mainly in the form of Pb 2+ in our samples and the larger a and c parameters may result from the larger proportion of Pb 2+ in the rock salt layer. A previous study on YSr 2 Cu 3−x Mo x O y indicated that Mo is doped into the Cu(I) sites [14]. Note that the 1212 phase can be derived from the 123 phase by substituting a rock salt layer for the Cu-O chain, we suggest that Mo mainly substitutes Pb 4+ and coexists with Pb 2+ in the rock salt layer.…”