RESUMO
The effect of chemical and hydrostatic pressure has been studied systematically in a selected system belonging to the 1111 family of iron pnictide high-temperature superconductors. The results show a surprising similarity between the trend of critical temperature vs hydrostatic pressure for isoelectronic samples with different rare earths (RE) on the RE site and samples of the SmFeAsO(1-x)F(x) series with different doping levels. These results open new questions about the underlying mechanism for superconductivity in iron pnictides.
RESUMO
In this Article, we provided the complete phase diagram of NdFeAsO(1-x)F(x) solid solution as a function of electron doping thanks to the careful determination of F- and O-content and phase content. We gave direct evidence of the source of F-depletion in the superconducting main phase, that is, the formation of oxyfluoride spurious phase. The approach reported in this work clearly showed that to give reliable results on these complex new superconducting materials, a rigorous control of the chemical composition of the considered phases has to be carried out.
RESUMO
In this paper we show the relevant role of F-content control in pnictide oxide superconductors by providing a direct evidence of F-loss in samples prepared by means of routine synthetic methods.
RESUMO
In this communication we report the unexpected effect of ruthenium doping in sodium lightly doped manganites. This effect seems to be in contrast with the usual model applied to describe the effect of this magnetic ion into the manganite structure. We propose a possible compensation mechanism which seems also able to describe other peculiar features encountered in these materials.
