Author:
Masi A.,Alvani C.,Angrisani Armenio A.,Augieri A.,Celentano G.,De Marzi G.,Fiamozzi Zignani C.,Fabbri F.,La Barbera A.,Padella F.,Rizzo F.,Silva E.,Vannozzi A.
Abstract
Abstract
In this paper, the effect of post synthesis annealing treatments on a Fe(Se,Te) polycrystalline material is evaluated and discussed. The samples have been obtained via melting route. The material has been subjected to a high-temperature annealing treatment, carried out for 45 h at 680 °C. The role of the cooling step was investigated comparing samples obtained after a controlled cooling or after quenching in liquid nitrogen. From a morpho-structural point of view, the annealing treatment improves homogeneity, with respect to pristine samples, and influences secondary phase precipitate morphology. Regarding superconducting properties, a key role of the cooling procedure is assessed: controlled cooling leads in fact to a significant improvement of high field behaviour with respect to the melted material, while quenched samples are characterized by a worsening of the superconducting properties. Despite the overall worsening, however, the quenched samples show evidence of the presence of superconducting phases characterized by a remarkably high critical temperature (Tc
> 18 K), observed for these materials only in films or under pressure.
Subject
General Physics and Astronomy