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首页> 外文期刊>Chemistry: A European journal >Micro- to macroscopic observations of MnAlPO-5 nanocrystal growth in ionic-liquid media
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Micro- to macroscopic observations of MnAlPO-5 nanocrystal growth in ionic-liquid media

机译：离子液体介质中MnAlPO-5纳米晶体生长的微观到宏观观察

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摘要

Micro- and macroscopic studies of nucleation and growth processes of MnAlPO-5 nanosized crystals under ionothermal synthesis conditions are reported herein. The samples treated at 150°C were extracted from the reaction mixture at various stages of crystallization, and characterized by XRD; SEM; thermogravimetric analysis (TGA); ~(31)P and ~(27)Al solid-state magic angle spinning (MAS) NMR, Raman, UV/Vis, and X-ray fluorescence spectroscopy (XRF). The starting raw materials (alumina, manganese, and phosphorous) were dissolved completely in the ionic liquid and transformed into an amorphous solid after 5h of ionothermal treatment. This amorphous solid then undergoes structural changes over the following 525h, which result in an intermediate phase that consists of octahedral Al species linked to the manganese and phosphate species. The first MnAlPO-5 nuclei on the surface of the intermediate can be observed after 50h ionoheating. These nuclei further grow, as the surface of the intermediate is in full contact with the ionic liquid, to give crystalline MnAlPO-5 nanoparticles with a mean diameter of 80nm. The crystals become fully detached from the intermediate and are then liberated as discrete particles after 90h heating. The transformation process from amorphous to intermediate and then to the crystalline MnAlPO-5 nanoparticles shows that nucleation starts at the solidliquid interface and continues through surface-to-core reversed-growth until the entire amorphous solid is transformed into discrete nanocrystals.
机译：本文报道了在电热合成条件下MnAlPO-5纳米晶体的成核和生长过程的微观和宏观研究。在结晶的各个阶段从反应混合物中提取在150°C处理的样品，并通过XRD进行表征;扫描电镜热重分析（TGA）; 〜（31）P和〜（27）Al固态幻角旋转（MAS）NMR，拉曼光谱，UV / Vis和X射线荧光光谱（XRF）。将原料（氧化铝，锰和磷）完全溶解在离子液体中，并在电离处理5小时后转变为无定形固体。然后，该无定形固体在随后的525h内发生结构变化，从而导致中间相，该中间相由与锰和磷酸盐物种相连的八面体Al物种组成。在电加热50小时后，可以观察到中间体表面上的第一个MnAlPO-5核。当中间物的表面与离子液体完全接触时，这些核进一步生长，从而得到平均直径为80nm的结晶MnAlPO-5纳米颗粒。晶体从中间体中完全脱离，然后在加热90h后释放为离散颗粒。从非晶态转变为中间态，然后再转变为结晶MnAlPO-5纳米粒子的过程表明，成核始于固液界面，并通过表面至核心的反向生长继续进行，直到整个非晶态固体转变为离散的纳米晶体。

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