微波水热法制备ZnO纳米晶

Preparation of ZnO Nanocrystallites by Microwave Hydrothermal Process

采用微波水热(microwave hydrothermal,M-H)法在MDS-6型温压双控微波水热反应仪中成功地制备出平均晶粒尺寸为30 nm且呈现棒状形貌的ZnO纳米晶。并在一定的水热温度和反应时间下系统研究了微波水热反应过程中[Zn2+]离子浓度、反应釜填充比、反应物浓度比[Zn2+]/[OH-]等工艺因素对ZnO纳米晶的晶粒尺寸及形貌的影响。采用X射线衍射仪(XRD)、场发射扫描电子显微镜(FE-SEM)和透射电子显微镜(TEM)对所制备的ZnO纳米晶进行表征。结果表明:所制备ZnO的平均晶粒尺寸约为30 nm,ZnO纳米晶呈现棒状形貌。随着[Zn2+]离子浓度的增加,ZnO纳米晶的晶粒尺寸先减小后增大;随着反应釜填充比和反应物浓度比[Zn2+]/[OH-]的增大,ZnO纳米晶的晶粒尺寸先减小后增大,并逐渐趋于稳定。制备ZnO纳米晶的最佳反应条件为:[Zn2+]=1.6 mol.L-1;反应釜填充比=70%;[Zn2+]/[OH-]=1/2。

ZnO nanocrystallites with the average grain size of about 30 nm and a rod-like morphology have been prepared successfully by a novel microwave hydrothermal （M-H） process in a MDS-6 microwave digestion/extraction system. The influential factors, such as [ Zn2＋] concentrations, filling ratios of the autoclave, concentration ratios of [ Zn2＋ ]/[ OH-] have been studied in detail under the designated hydrothermal temperature and reaction time. The as-prepared ZnO nanocrystallites were characterized by the means of X-ray diffraction （XRD）, field emission scanning electron microscope （FE-SEM） and transmission electron microscope （TEM）. It is found that rod-like ZnO nanocrystallites with the average grain size about 30 nm are prepared. As the increase of [ Zn2 ＋ ] concentrations, the size of as-obtained ZnO nanocrystallites firstly decreases, then increases. The size of as-obtained ZnO nanocrystallites firstly decreases, then increases and finally approaches stable with the increases of filling ratio of the autoclave and concentration ratio of [ Zn2＋ ]/[ OH-]. To get nearly uniform ZnO nanocrystallites, optimal [Zn2＋ ] concentration condition, filling ratio of the autoclave and concentration ratio of [ Zn2＋ ]/[ OH-] should be kept at 1.6 mol · L^-1, 70% ,and 1/2, respectively.