Controlled synthesis, growth mechanism and optical properties of FeWO4 hierarchical microstructures
Controlled synthesis, growth mechanism and optical properties of FeWO4 hierarchical microstructures
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DOI：
10.1039/c1ce05416c
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发表时间：
2011-09
期刊：
影响因子：
3.1
通讯作者：
Jian Zhang;Yang Wang;Shikuo Li;Xiufang Wang;F. Huang;A. Xie;Yuhua Shen
中科院分区：
文献类型：
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作者：
Jian Zhang;Yang Wang;Shikuo Li;Xiufang Wang;F. Huang;A. Xie;Yuhua Shen
以乙二胺四乙酸二钠（Na 2 EDTA）和六次甲基四胺（HMT）为原料，采用水热法合成了具有分级纳/微结构的单斜晶系钨酸亚铁（FeWO 4）微晶。HMT扮演还原剂、碱源和晶体生长调节剂的三重角色，而Na 2 EDTA充当螯合剂和结构导向剂。合成多层花状FeWO 4的适宜条件为200 °C，Na 2 EDTA和HMT的浓度分别为0.03 mol L-1和0.025 mol L-1，反应8 h。随着Na 2 EDTA浓度的增加，FeWO 4的形貌由大块的非晶态向多层的六角微晶转变，而随着HMT浓度的增加，FeWO 4的六角结构向六重对称结构转变，对称轴的纵横比逐渐减小。Ostwald熟化和自组装过程被认为是其可能的形成机制。多层FeWO 4微晶的光致发光（PL）强度高于其他FeWO 4结构。磁性测量的六角FeWO 4微晶在低温下表现出一个小的铁磁有序。此外，这项工作可能开辟新的路线，螯合试剂辅助合成具有各种形态的分级结构。
Monoclinic ferrous tungstate (FeWO4) microcrystals with hierarchical nano/microstructures have been selectively synthesized via a facile hydrothermal process in the presence of ethylenediamine tetraacetic acid disodium salt (Na2EDTA) and hexamethylenetetramine (HMT). HMT played triple roles as the reducing agent, alkaline source, and crystal growth modifier, while Na2EDTA served as the chelating reagent and structure-directing agent. The appropriate conditions for synthesis of multilayer flower-like FeWO4 were 200 °C and 8 h with the concentrations of Na2EDTA and HMT at 0.03 mol L−1 and 0.025 mol L−1, respectively. The morphology of FeWO4 showed dramatic changes from a bulky amorphous crystal to multilayer hexangular microcrystals with increasing Na2EDTA concentration, while increasing HMT concentration would transform the hexagonal structure to a sixfold symmetry architecture and the aspect ratio of symmetry axis decreased gradually. Ostwald ripening and the self-assembled process was proposed for the possible formation mechanism. The photoluminescence (PL) intensity of the multilayer FeWO4 microcrystals was higher than that of other FeWO4 structures. Magnetic measurement of hexangular FeWO4 microcrystals showed a small ferromagnetic ordering at low temperature. Furthermore, this work may open novel routes to the chelating reagent-assisted synthesis of hierarchical architectures with various morphologies.