Effect of Sr substitution on irreversibility line, lattice dynamics and formation of Hg,Pb-1223 superconductors

Structural and Superconducting Properties of Hg0.75Re0.25Ba2−xSrxCa2Cu3O8+δ Superconductors Grown by Sol–Gel and Sealed Quartz Tube Synthesis

“…This variation may be attributed to the change of the Re}O , Hg}O , and Cu}O bonds induced by the strontium substitution, in the same way as shown in the Pb-doped Hg-1223 system (31). To obtain an approximate estimation of the bond length change, we use an approach similar to that applied to Y-123 and (Hg,Pb)-1223 both partially substituted by Sr (31,32). This model assumes the following relationship between bond lengths and phonon frequency, mainly due to the compression of the Cu}O bond in both cases, and that Hg}O and Re}O behave more rigidly.…”

“…It is reasonable to expect that the main decrease of the c-axis corresponds to the contraction of the blocking block as has been shown by the data taken in Re-doped samples, including complete Sr substitution (15) and Sr-free samples (22). One then expects to have some frequency variations in the Raman modes that are associated with the bonds related to this block layer (31). The frequency variation with strontium content of the modes related to the Hg}O }Cu and Re}O }Cu bonds is shown in Fig.…”

“…This model assumes the following relationship between bond lengths and phonon frequency, mainly due to the compression of the Cu}O bond in both cases, and that Hg}O and Re}O behave more rigidly. The rigidity of the O }Hg}O bond is coincident with the (Hg,Pb)-1(Sr)223 system (31). Moreover, the contraction of the Hg}Cu bond due to the application of high external pressure goes in the same way (23).…”

“…We see that both modes increase in frequency with increasing Sr content. This variation may be attributed to the change of the Re}O , Hg}O , and Cu}O bonds induced by the strontium substitution, in the same way as shown in the Pb-doped Hg-1223 system (31). To obtain an approximate estimation of the bond length change, we use an approach similar to that applied to Y-123 and (Hg,Pb)-1223 both partially substituted by Sr (31,32).…”

Effect of Sr-for-Ba isovalent substitution on the local structure, hole distribution and magnetic irreversibility of Cu(Ba,Sr)2YbCu2O6.95(2)

“…It induces a contraction in BB, and might therefore be expected to improve the H irr characteristics. Quite importantly, for the Hg-based HTSCs replacing the larger Ba with the smaller Sr was proven to be an effective way to enhance the H irr values [9,[17][18][19] [20]. In fact, the first observation of the decrease in the critical current (J c ) characteristics in Cu-1212 with Sr substitution is from 1991 by Parent and Moreau [21].…”