KOH和温度对水热合成α-FeOOH纳米线的影响

Effects of KOH and temperature on hydrothermal synthesis of α-FeOOH nanowire

以硝酸铁为原料、KOH为矿化剂,用水热反应合成了α-FeOOH纳米线粉体,利用X-射线衍射仪(XRD)、透射电子显微镜(TEM)、选区衍射(SAED)对产物的物相和微观形貌进行了表征,研究了矿化剂KOH的浓度和水热反应温度对物相形成和微观形貌的影响.结果表明,当KOH的浓度为0.1 mol/L,反应温度为100℃,反应时间为6 h时,所得样品为正交相的α-FeOOH纳米线;随着KOH的浓度的增加,α-FeOOH的结晶性逐渐下降,产物中有少量的六方相α-Fe2O3晶体出现;当KOH的浓度达到2.0 mol/L时,产物为无定形相;在较低温度(40℃)下,KOH的浓度对产物的结晶性没有影响,产物均为无定形相;在高温(200℃)下,水热过程中产生的α-FeOOH纳米线会快速转化为六方相的α-Fe2O3晶体,并且KOH的浓度的提高会增加α-Fe2O3晶体的尺寸.

By using Fe（NO3）3·9H2O as the starting materials, caustic potash as the mineralizer,α-FeOOH nanowires were prepared by hydrothermal method. The phase and micro-morphology of the products were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM） and selected area electron diffraction （SAED）. The effects of mineralizer concentration and reaction temperature on the phase formation and morphology were investigated. Results indicated that α-FeOOH nanowires with orthorhombic structure could be successfully synthesized via hydrothermal processing with 0.1 mol/L KOH at 100 ℃ for 6 h. With the increase of mineralizer concentration, α-FeOOH phase decreases and hexagonal α-Fe2O3 phase appears. When mineralizer concentration is 2.0 mol/L, no crystal phase is obtained. There is no effect of mineralizer concentration on the crystal structure of products at low temperature （40℃）, for only amorphous phase is obtained under various concentration. At high temperature （200℃）, α-FeOOH phase can be converted into hexagonal α-Fe2O3 phase rapidly and the size of α-Fe2O3 becomes larger with the increase of mineralizer concentration.