Effect of Fluorination on the Structure and Superconducting Properties of the Hg-1201 Phase
1998; American Physical Society; Volume: 80; Issue: 2 Linguagem: Inglês
10.1103/physrevlett.80.385
ISSN1092-0145
AutoresArtem M. Abakumov, В. Л. Аксенов, V. A. Alyoshin, Е.В. Антипов, А. М. Балагуров, Daria Mikhailova, S.N. Putilin, Marina G. Rozova,
Tópico(s)Inorganic Fluorides and Related Compounds
ResumoA fluorination of the reduced $\mathrm{HgBa}{}_{2}{\mathrm{CuO}}_{4+\ensuremath{\delta}}(\mathrm{Hg}\ensuremath{-}1201)$ with ${T}_{c}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}61\mathrm{K}$ resulted first in an increase in ${T}_{c}$ up to 97 K and then in a decrease and even a suppression of superconductivity due to overdoping. Neutron powder refinements performed on fluorinated $\mathrm{HgBa}{}_{2}{\mathrm{CuO}}_{4}\mathrm{F}{}_{\ensuremath{\delta}}$ showed twice the amount of extra fluorine in comparison with those for the oxygenated $\mathrm{Hg}\ensuremath{-}1201$ phases with close ${T}_{c}$. This supports the ionic model of doping in $\mathrm{Hg}\ensuremath{-}1201$: two holes per oxygen and one hole per fluorine. The apical distances in $\mathrm{Hg}\ensuremath{-}1201$ depend on the number of dopant atoms rather than on their charge. The exchange of extra oxygen for a double amount of fluorine shortens the apical $\mathrm{Cu}\ensuremath{-}\mathrm{O}$ distances, while the in-plane distances and ${T}_{c}$ do not vary.
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