Study of the dissolution behavior of selenium and tellurium in different solvents - a novel route to Se, Te tubular bulk single crystals

The characteristics of selenium in various solvents under solvothermal conditions were investigated in detail and the different dissolution behavior of selenium in the solvents identified. A brown homogeneous solution was obtained in ethylenediamine. This solution is metastable and is a suitable selenium feedstock for the preparation of selenides at room temperature. A nucleophilic mechanism is proposed for the formation of metal selenides. Millimeter-scale selenium crystals were obtained in the other solvents, i.e. ethanol, pyridine, benzene, toluene, and carbon tetrachloride (CCl4). XRD and ED patterns indicate that the crystals grew in orientation. SEM images show that these crystals have a tubular hexagonal prism morphology with tubular sizes of ca. 1-1.5 mm in length, 15 mm in diameter and 5 mm in thickness. We also prepared micro-tubular tellurium crystals in ethylenediamine. The growth mechanism of the tubular crystals is discussed.