Juelsholt Mikkel, Aalling-Frederiksen Olivia, Lindahl Christiansen Troels, Kjær Emil T S, Lefeld Niels, Kirsch Andrea, Jensen Kirsten M Ø
Department of Chemistry, University of Copenhagen, Universitetsparken 5, Copenhagen 2100, Denmark.
Institute of Inorganic Chemistry and Crystallography, University of Bremen, Leobener Strasse/NW2, D-28359 Bremen, Germany.
Inorg Chem. 2023 Sep 18;62(37):14949-14958. doi: 10.1021/acs.inorgchem.3c01659. Epub 2023 Sep 1.
Understanding material nucleation processes is crucial for the development of synthesis pathways for tailormade materials. However, we currently have little knowledge of the influence of the precursor solution structure on the formation pathway of materials. We here use total scattering to show how the precursor solution structure influences which crystal structure is formed during the hydrothermal synthesis of tungsten oxides. We investigate the synthesis of tungsten oxide from the two polyoxometalate salts, ammonium metatungstate, and ammonium paratungstate. In both cases, a hexagonal ammonium tungsten bronze (NH)WO is formed as the final product. If the precursor solution contains metatungstate clusters, this phase forms directly in the hydrothermal synthesis. However, if the paratungstate B cluster is present at the time of crystallization, a metastable intermediate phase in the form of a pyrochlore-type tungsten oxide, WO·0.5HO, initially forms. The pyrochlore structure then undergoes a phase transformation into the tungsten bronze phase. Our studies thus experimentally show that the precursor cluster structure present at the moment of crystallization directly influences the formed crystalline phase and suggests that the precursor structure just prior to crystallization can be used as a tool for targeting specific crystalline phases of interest.
了解材料成核过程对于开发定制材料的合成途径至关重要。然而，目前我们对前驱体溶液结构对材料形成途径的影响知之甚少。我们在此利用全散射来展示前驱体溶液结构如何影响氧化钨水热合成过程中形成的晶体结构。我们研究了由两种多金属氧酸盐盐，即偏钨酸铵和仲钨酸铵合成氧化钨的过程。在这两种情况下，最终产物均为六方铵钨青铜（NH）WO。如果前驱体溶液含有偏钨酸根簇，该相在水热合成中直接形成。然而，如果在结晶时存在仲钨酸B簇，则最初会形成一种以烧绿石型氧化钨WO·0.5HO形式存在的亚稳中间相。然后，烧绿石结构会经历相转变成为钨青铜相。我们的研究因此通过实验表明，结晶时存在的前驱体簇结构直接影响所形成的晶相，并表明结晶前的前驱体结构可作为靶向特定感兴趣晶相的工具。
