Scholarlink

<p>Crystal phases in the system MgCl<sub>2</sub>–OC(NH<sub>2</sub>)<sub>2</sub>–H<sub>2</sub>O have been studied and discussed. The conditions for obtaining MgCl<sub>2</sub>·OC(NH<sub>2</sub>)<sub>2</sub>·4H<sub>2</sub>O, MgCl<sub>2</sub>·4OC(NH<sub>2</sub>)<sub>2</sub>·2H<sub>2</sub>O, MgCl<sub>2</sub>·6OC(NH<sub>2</sub>)<sub>2</sub> and MgCl<sub>2</sub>·10OC(NH<sub>2</sub>)<sub>2</sub> have been specified. The crystal structures of MgCl<sub>2</sub>·OC(NH<sub>2</sub>)<sub>2</sub>·4H<sub>2</sub>O and MgCl<sub>2</sub>·6OC(NH<sub>2</sub>)<sub>2</sub> have been solved for the first time. The thermal behavior of the four studied phases has been investigated in the temperature range from room temperature to 600&#xa0;°C applying simultaneous thermal and mass-spectroscopy analyses. In-situ time-resolved powder diffraction analysis in the temperature range from 25 to 230&#xa0;°C has been used in order to clarify the structural transformations upon heating. Research has revealed that the most stable compound upon heating is MgCl<sub>2</sub>·6OC(NH<sub>2</sub>)<sub>2</sub>. For all the studied samples, the decomposition of the urea component has been observed to start closely after the melting. The decomposition processes are more complex for the H<sub>2</sub>O-containing phases, where the water molecules releasing occurs in stages. Magnesium analog of bis-biuret-zinc-chloride have been detected among the intermediate phases obtained during the decomposition of the studied compounds.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Crystal phases in the system MgCl2–OC(NH2)2–H2O: thermal stability and decomposition

  • 期刊论文

  • 出版模式：

    开放获取

  • 发表日期：

    2025年11月12日

查看全文
  • Nadia Petrova,
  • Vladislav Kostov-Kytin,
  • Krasimir Kossev,
  • Rosica Nikolova

摘要

Crystal phases in the system MgCl2–OC(NH2)2–H2O have been studied and discussed. The conditions for obtaining MgCl2·OC(NH2)2·4H2O, MgCl2·4OC(NH2)2·2H2O, MgCl2·6OC(NH2)2 and MgCl2·10OC(NH2)2 have been specified. The crystal structures of MgCl2·OC(NH2)2·4H2O and MgCl2·6OC(NH2)2 have been solved for the first time. The thermal behavior of the four studied phases has been investigated in the temperature range from room temperature to 600 °C applying simultaneous thermal and mass-spectroscopy analyses. In-situ time-resolved powder diffraction analysis in the temperature range from 25 to 230 °C has been used in order to clarify the structural transformations upon heating. Research has revealed that the most stable compound upon heating is MgCl2·6OC(NH2)2. For all the studied samples, the decomposition of the urea component has been observed to start closely after the melting. The decomposition processes are more complex for the H2O-containing phases, where the water molecules releasing occurs in stages. Magnesium analog of bis-biuret-zinc-chloride have been detected among the intermediate phases obtained during the decomposition of the studied compounds.