Synthesis of Ca2-xSrxCuO2F2 (0 ≤ x ≤ 2) with the T΄-structure through fluorination of Ca2-xSrxCuO3 with poly(vinylidene fluoride)/poly(tetrafluoroethylene)

Abstract

In this paper, the synthesis of the series, Ca2-xSrxCuO2F2 (0 ≤ x ≤ 2), is reported by the fluorination of Ca2-xSrxCuO3 starting materials with poly(vinylidene fluoride)/poly(tetrafluoroethene). The structural refinements showed that all samples adopt the T΄-structure, in contrast to the previous observation of the T -structure for Sr2CuO2F2+δ, when the phase is synthesised using F2 gas. The difference can be related to the lack of interstitial fluoride ions (δ =0) in the samples synthesised via fluorination with the polymers, and hence highlights that the T- structure is only formed if there is partial oxidation of Cu through incorporation of interstitial fluoride ions (δ>0), as is the case when F2 gas is employed.