锌铬尖晶石水热合成及形成机理研究

Formation Mechanism of Hydrothermally Synthesized ZnCr_2O_4 Crystallites

采用水热法制备了纳米ZnCr2O4晶粒。采用X-射线衍射(XRD)、透射电子显微镜(TEM)和红外光谱仪(IR)研究了晶粒的物相演化规律。结果表明,在180℃温度下可制备2 nm的ZnCr2O4晶粒。ZnCr2O4晶粒的形成遵循溶解-结晶机制,铬的三聚体和含有羟基的四配位锌的聚集体形成与Al13结构相同的ZnCr12,这些ZnCr12晶核经过进一步缩聚反应形成ZnCr2O4晶粒。

The nano-sized ZnCr204 crystallites were synthesized by hydrothermal method. The phase evolutions were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM） and infrared spectrum（IR）. The results indicate that the ZnCr2O4 crystallites with 2nm were hydrothermally prepared at 180 ℃. Growth of ZnCr204 by dissolution-crystallization process may be interpreted as taking place from the Cr-trimer. Four Cr-trimers and one zinc complex with not less than one OH ligand olated to form ZnCr12, isostructural species Al13-1ike species, which can be viewed as being a sub-unit of the ZnCr2O4 crystal structure. Further condensation of ZnCr12 nucleus forms the ZnCr2O4 crystallites.