Effect of fluorine on the critical current density of thallium based highT c superconductors

Hole doping in high temperature superconductors using the XANES technique

“…It is known that the interstitial oxygen site O(3) in the Hg-O plane of Hg-1223 is almost vacant [25][26][27]; therefore addition of fluorine will fill this empty oxygen vacancy and hence increases the number of holes in the CuO 2 planes in the originally under-doped compound. Due to the high ionic and electronegative nature of F − , it will show less hybridization with mercury and thus each fluorine ion will donate nearly one hole to the CuO 2 planes [21,22,25,26]. This is unlike what happens in the case of fluorine addition to Tl-1223 with similar structure [1].…”

“…This made us believe that there is still a possibility of further improving the superconducting properties, which could be attempted by anion substitution. Therefore, and because we have achieved considerable improvements in the superconducting properties and phase formation of Tl-1223 through fluorine substitution [1,[21][22][23][24], we have attempted to optimize the properties of Hg-1223 by introducing fluorine into the structure for both the Pb-doped (HgPb-1223 and the Re-doped HgRe-1223). In this work we will restrict our discussions to the HgPb-1223 system.…”

“…In this work we will restrict our discussions to the HgPb-1223 system. Although Tl-1223 and HgPb-1223 phases have similar structures, there is a major difference that affects the hole distribution in the CuO 2 planes and hence the electronic structure of both compounds [21][22][23][24][25]. This difference is in the O site of Tl-O and the corresponding Hg-O planes where it is fully occupied and partially filled in Tl-1223 and Hg-1223, respectively.…”

“…Therefore, fluorine was introduced in the Cu-O planes in the case of Tl-1223 but it was expected to fill the partially filled site in the Hg-O planes in Hg-223. This led to increasing the hole concentration of the originally under-doped Hg-1223, and to decreasing it in the over-doped Tl-1223 [21][22][23][24][25][26].…”

Analysis of the fluoride effect on the phase-selective growth of TlBa2Ca2Cu3O9−x thin films: Phase evolution and microstructure development

“…Watanabe 16 reported slight enhancement of bulk BPSCCO-2223 J c upon addition of BiF 3 . 21 Hamdan and collaborators investigated (Tl/Bi)(Ba/Sr) 2 Ca 2 Cu 3 O x F y (TBSBCCO) bulk samples and noted enhancement of T c and J c with respect to fluoride doping level, 22 formation of pinning centers, and further J c enhancement by exposing the samples to ␥-irradiation 23 and fluoride incorporation into the HTS lattice. 18 One group reported that fluorination significantly increases the T c of some HBCCO samples.…”