School of Chemistry and Environmental Studies, Faculty of Applied Sciences, Universiti Teknologi MARA, Shah Alam, Selangor 40450, Malaysia ; Centre for Nanomaterials Research, Institute of Science, Universiti Teknologi MARA, Level 3, Block C, Shah Alam, Selangor 40450, Malaysia.
School of Physics and Materials Studies, Faculty of Applied Sciences, Universiti Teknologi MARA, Shah Alam, Selangor 40450, Malaysia ; Centre for Nanomaterials Research, Institute of Science, Universiti Teknologi MARA, Level 3, Block C, Shah Alam, Selangor 40450, Malaysia.
Nanoscale Res Lett. 2014 Mar 21;9(1):134. doi: 10.1186/1556-276X-9-134. eCollection 2014.
In the preparation of nanostructured materials, it is important to optimize synthesis parameters in order to obtain the desired material. This work investigates the role of complexing agents, oxalic acid and tartaric acid, in the production of MgO nanocrystals. Results from simultaneous thermogravimetric analysis (STA) show that the two different synthesis routes yield precursors with different thermal profiles. It is found that the thermal profiles of the precursors can reveal the effects of crystal growth during thermal annealing. X-ray diffraction confirms that the final products are pure, single phase and of cubic shape. It is also found that complexing agents can affect the rate of crystal growth. The structures of the oxalic acid and tartaric acid as well as the complexation sites play very important roles in the formation of the nanocrystals. The complexing agents influence the rate of growth which affects the final crystallite size of the materials. Surprisingly, it is also found that oxalic acid and tartaric acid act as surfactants inhibiting crystal growth even at a high temperature of 950°C and a long annealing time of 36 h. The crystallite formation routes are proposed to be via linear and branched polymer networks due to the different structures of the complexing agents.
在制备纳米结构材料时，优化合成参数以获得所需的材料非常重要。本工作研究了络合剂草酸和酒石酸在氧化镁纳米晶合成中的作用。同步热分析（STA）的结果表明，两种不同的合成路线得到的前驱体具有不同的热特性。发现前驱体的热特性可以揭示热退火过程中晶体生长的影响。X 射线衍射证实最终产物是纯的、单相的和立方形状的。还发现络合剂可以影响晶体生长速度。草酸和酒石酸的结构以及络合位点在纳米晶体的形成中起着非常重要的作用。络合剂影响生长速度，从而影响材料的最终晶粒尺寸。令人惊讶的是，还发现草酸和酒石酸即使在 950°C 的高温和 36 小时的长退火时间下，也可以作为表面活性剂抑制晶体生长。由于络合剂的结构不同，晶核形成途径被认为是通过线性和支化聚合物网络。
