Beschreibung:
We prepared a series of Fe 1-x Cr x Se 1-y Te y polycrystalline bulks with solid state reaction method and measured the surface morphology, structure and superconducting properties of the samples. The results indicate that the optimal superconducting transition temperature T c of the as-grown samples is up to 16.03 K when the nominal stoichiometry is Fe 0.9 Cr 0.1 Se 0.7 Te 0.3 . The effects of Cr substitution in crystal structure, transition temperature and other characterization are discussed. In addition, we explored heat treatment to as-grown samples, finding that annealing contributes to improving superconducting properties while re-sintering doesn’t. T c of Fe 0.94 Cr 0.06 Se 0.5 Te 0.5 is raised from 15.54 K to 16.23 K after annealing. Results show that Cr doesn’t incorporate into the crystal structure, which means Cr introduces chemical pressure to Fe(Se,Te) crystal via difference of atomic size between Cr atom and Fe atom