Ammonothermal synthesis of binary and multinary nitrides, amides and imides of Ga, Al, Si and Ge

在过去的几年里，主族氮化物成为众多研究的焦点。尤其是III族(Al，Ga，In)和IV族(Si，Ge)元素的化合物表现出有趣的材料性质。因此，典型的合成是基于分子前体的热解、在相当高的温度下的固相反应或使用盐或金属作为助熔剂。这些路线通常只能访问这些三元或多元化合物的微米级单晶。在这里，氨单热反应可能是一个有吸引力的替代方案。长期以来，溶剂热合成在生长单晶方面的巨大潜力，例如石英的水热处理，是众所周知的。一种类似的技术可以用于使用超临界氨合成氮化物，超临界氨既可以作为溶剂，也可以作为氮源。除了Forschergruppe AmmonFOR1600氨热处理之外，氨热处理只有很小的应用，尽管学术背景已经在德国产生了几十年。这一子项目的范围是重新建立氨热合成，重点是新型多元氮化物的合成和晶体生长，包括元素Al、Ga、Mg、Li、Si或Ge。到目前为止，合成过程中得到的氮化物，也包括碱和碱土或稀土金属以及中间体，将进行结构表征。了解反应机理和中间体的表征有助于有针对性地合成新型氮化物化合物。此外，阐明这些氮化物的结构、研究材料性质和了解结构-性质关系也是至关重要的。在第一个资助期内，有可能优化合成条件和评价适当的多元模型化合物。研究表明，纤锌矿结构或相关超结构(如LiSbN3或CaAISiN3)中结晶的氮化物似乎是很有前途的候选模型。

During the last couple of years, main group nitrides got in the focus of numerous investigations . Especially compounds of group III (Al, Ga, In) and group IV (Si, Ge) elements show interesting material properties . Typical syntheses are hereby based on pyrolysis of molecular precursors, solid-state reactions at rather high temperatures or the use of salts or metals acting as fluxing agents. These routes usually enable access only to single crystals inµm scale of these ternary or multinary compounds . Here, ammonothermal reactions could be an attractive alternative. The huge potential of solvothermal syntheses for growing !arge single crystals, for example hydrothermal processing of quartz, is well known for a long time. A similar technique can be used for the synthesis of nitrides employing supercritical ammonia, which can act as solvent as well as nitrogen source. Beyond the Forschergruppe AmmonoFOR1600 ammonothermal processing finds only minor application, although the academic background has been generated in Germany decades ago . The scope of this subproject is to reestablish ammonothermal synthesis, focusing on synthesis and crystal growth of novel multinary nitrides including the elements Al, Ga, Mg, Li, Si or Ge. Hitherto, nitrides, also including alkaline and alkaline earth or rare earth metals as well as intermediates, obtained during synthesis will be structurally characterized. Understanding reaction mechanisms and characterization of intermediates should help to enable a targeted synthesis of novel nitride compounds . Furthermore, it is essential to elucidate the structures of these nitrides, investigate material properties and understand structure-property­ relationships. Within the first funding period it was possible to optimize synthesis conditions and to evaluate appropriate multinary model compounds. lnvestigations showed that nitrides crystallizing in wurtzite type of structure or related superstructures (e.g. LiSbN3 or CaAISiN3)seem to be very promising model candidates.