Probing Molten Salt Flux Reactions Using Time-Resolved in Situ High-Temperature Powder X-ray Diffraction: A New Synthesis Route to the Mixed-Valence NaTi2O4
Probing Molten Salt Flux Reactions Using Time-Resolved in Situ High-Temperature Powder X-ray Diffraction: A New Synthesis Route to the Mixed-Valence NaTi2O4
复制标题
使用时间分辨原位高温粉末 X 射线衍射探测熔盐通量反应：混合价 NaTi2O4 的新合成路线
DOI：
10.1021/cm034770w
复制
发表时间：
2004
影响因子：
8.6
通讯作者：
D. O′Hare
中科院分区：
文献类型：
--
作者：
Margret J. Geselbracht;L. Noailles;and Lien T. Ngo;Jessica H. Pikul;R. Walton;E. S. Cowell;and Franck Millange;D. O′Hare
一种合成混合价态钛酸钠NaTi₂O₄的新型熔盐合成路线已被发现。在770°C下，将Na₈Ti₅O₁₄与金属钛粉在摩尔比为3:1的NaCl:KCl混合物中反应，生成了NaTi₂O₄晶体。使用熔盐助熔剂使该化合物的合成温度降低了400°C以上。采用时间分辨原位高温X射线粉末衍射来探究反应的动力学和机理。能量色散X射线衍射（EDXRD）数据显示反应迅速；在770°C下，30分钟时该相开始形成，并且在2小时内产物基本完全形成。在反应过程中，熔盐助熔剂中始终存在结晶固体，这表明该机理很可能涉及由熔盐助熔剂介导的在固体颗粒表面发生的反应。通过EDXRD和淬火研究确定的可能的关键中间产物是Ti₃O、Na₂Ti₆O₁₃和Na₀.₅₄TiO₂。这种新的熔盐合成……
A new molten salt synthesis route to the mixed-valence sodium titanate NaTi2O4 has been discovered. Reduction of Na8Ti5O14 by Ti metal powder in a 3:1 molar mixture of NaCl:KCl at 770 °C produced crystals of NaTi2O4. Use of the molten salt flux lowered the synthesis temperature of this compound by over 400 °C. Time-resolved in situ high-temperature X-ray powder diffraction was used to probe the kinetics and mechanism of the reaction. Energy-dispersive X-ray diffraction (EDXRD) data revealed that the reaction is rapid; the phase begins to form in 30 min at 770 °C, and product formation is essentially complete within 2 h. Crystalline solids are present in the molten salt flux at all times during the course of the reaction, indicating that the mechanism most likely involves reactions occurring at the surfaces of the solid particles, mediated by the molten salt flux. Possible key intermediates identified through EDXRD and quenching studies are Ti3O, Na2Ti6O13, and Na0.54TiO2. This new molten salt synthesis ro...