Short-term synthesis of poly- and single-crystalline iron monochalcogenides

Poly- and single-crystalline samples of the Fe(Se,Te)$_{1-\delta}$ system have been synthesized for short times by annealing bulk iron in chalcogen vapors and by reacting powdered iron with chalcogen melts. The lattice unit cell parameters and critical temperatures $(T_c)$ of the superconducting transition in the synthesized compounds agree with published data for the materials obtained by long-term synthesis using other methods. For Fe(Se$_{0.2}$Te$_{0.8}$)$_{0.82}$ block crystals, the temperature dependence of the second critical field in the vicinity of $T_c$ is linear with a slope of -4.9 T/K.