Solid-phase synthesis of chromium, cobalt and iron monoselenides with post-homogenization annealing for obtaining high-purity precursors for doped optical crystals
摘要
The creation of modern mid-infrared lasers requires the development of new advanced materials, including binary crystals AIIBVI, doped with transition metal ions (Cr2+, Co2+, Fe2+, and others). We developed a solid-phase method for obtaining high-purity monoselenides of chromium, iron, cobalt by the interaction of the metal with selenium in evacuated quartz ampoules. The obtained samples can be used for melt growth of optical crystals with isovalent doping. It is shown that the interaction of stoichiometric amounts of selenium with metals at temperatures of 800–900 °C is accompanied by the formation of a number of other selenides of non-stoichiometric composition. Thus, obtaining monoselenides requires additional homogenizing annealing at 900–950 °C for 120–240 h (5–10 days). Using X-ray structure analysis and infra-red spectroscopy, it was proven that after the annealing, the synthesized monoselenide compounds have a high degree of purity and are suitable for growing optical and laser chalcogenide crystals.