Investigations on self-organization and nucleation of meta-stable bismuth oxide polymorphs

到目前为止，在SPP 1415内进行的实验是基于实验和理论相结合的方法，并首次深入了解了氧化铋团簇的成核、稳定性和形成机制。铋氧簇合物是合成亚稳态铋氧化物晶型的起始原料。关于氧化铋晶型的形成和潜在机制的研究将在未来一段时间内得到扩展。使用能够稳定团簇的添加剂，以及反应条件的变化，可以获得控制氧化铋团簇生长的参数，从而控制氧化铋晶型的形成。离子迁移率质谱仪和电喷雾质谱仪将提供有关溶液成核过程和添加剂影响的现场信息。此外，还将进行DOSY-核磁共振、光散射实验，特别是原位同步辐射和X射线衍射谱实验。将确定从溶液结晶的第一步，并将研究生长机制。关于团簇生长和成核过程的实验将通过分子动力学模拟进行补充研究，以便更深入地了解分子尺度上的基本过程。不同大小的铋氧化物团簇的形成以及最终导致铋氧化物的缩合过程将被模拟。闪光灯退火和非平衡条件下铋氧化物团簇的等离子体处理可能提供获得新型亚稳态铋氧化物的途径。此外，稳定的β-Bi2O3纳米颗粒的高反应性将被用于制备亚稳定的同金属和异金属铋氧化物，例如通过机械力化学合成。

The experiments carried out so far within SPP 1415 are based on a combined experimental and theoretical approach and gave a first insight into the nucleation, stability and mechanism of formation for bismuth oxido clusters. The bismuth oxido clusters serve as starting materials for the synthesis of crystalline motifs of metastable bismuth oxides. The studies in terms of formation of bismuth oxide polymorphs and the underlying mechanisms will be extended in the forthcoming period. The use of additives, which are capable of cluster stabilization, and the variation of reaction conditions will give access to parameters that control the growth of bismuth oxido clusters and thus the formation of bismuth oxide polymorphs. Ion mobility mass spectrometry and ESI mass spectrometry will provide in situ information about the process of nucleation in solution and about the influence of additives. In addition DOSY-NMR, light scattering experiments and especially in situ synchrotron scattering and PXRD experiments will be carried out. The first steps of crystallization from solution will be identified and the growth mechanisms will be studied. The experiments regarding cluster growth and the process of nucleation will be complementary studied by molecular dynamics simulations in order to get deeper insight into the fundamental processes on a molecular scale. The formation of bismuth oxido clusters of various size as well as condensation processes leading finally to bismuth oxide will be modeled. Flash lamp annealing and plasma processing of bismuth oxido clusters under non-equilibrium conditions might offer access to novel metastable bismuth oxides. Additionally, the high reactivity of stabilized β-Bi2O3 nanoparticles will be used to prepare metastable homo- and heterometallic bismuth oxides, e.g. by mechanochemical synthesis.