SCHEDULED MAINTENANCE
Fluorination of the Ruddlesden–Popper type cuprates, Ln2–xA1+xCu2O6–y (Ln=La, Nd; A=Ca, Sr)
Abstract
The low-temperature (200–350 °C) fluorination of the Ruddlesden–Popper type cuprates, Ln2–xA1+xCu2O6–y(Ln=La, Nd; A=Ca, Sr) using F2 gas, CuF2 , and NH4F is reported. The incorporation of large levels of fluoride ions is observed for each of these fluorinating agents. The general characteristics of each method are discussed, and it is shown that for this system, fluorination mainly occurs by insertion of fluorine for reaction with F2 , substitution of fluorine for oxygen for NH4F, and a mixture of the two processes for CuF2 . For A=Sr, it is assumed that fluorine inserts mainly between the two CuO2 layers, since large expansions of the unit cell along the c direction are observed. No evidence for bulk superconductivity has so far been observed after fluorination.
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