Structural Transition of Gd2O3：Eu Induced by High Pressure

The structural transition of bulk and uano-size Gd2O3：Eu are studied by high pressure energy disperse x-ray diffraction （XRD） and high pressure photoluminescence. Our results show that in spite of different size of Gd2O3 particles, the cubic structure turns into a possible hexagonal one above 13.4 GPa. When the pressure is released, the sample reverses to the monoclinic structure. No cubic structure presents in the released samples. That is to say, the compression and relaxation of the sample leads to the cubic Gd2O3：Eu then turns into the monoclinic one.     

沸腾回流强迫水解法制备均分散α—Fe2O3超微粒水溶胶

Matijevic等曾报道在密闭静态环境下强迫水解酸化的铁盐溶液制备出几种形状单一的微米或亚微米级的均匀α-Fe_2O_3或β-FeOOH胶体粒子。类似的工作国内亦有报道。如粒子尺寸减小到纳米量级,则体系兼有表面效应、体积效应和特殊的光学性质。我们尝试用强迫水解法制备粒径几十纳米的球形或立方形的α-Fe_2O_3均分散胶体粒子,结果获得成功。     

单分散性CdSe纳米晶的合成——成核及其生长过程

 在氩气保护下,用三辛基亚磷酸和油酸分别作为Se和Cd的配位体,在260～300 ℃的十八烯溶液中合成了尺寸可控的CdSe纳米晶。该纳米晶不用进行进一步的提纯和尺寸分离就具有单分散性,其量子尺寸限域效应非常明显——吸收光谱的第一吸收峰峰位随着纳米晶的长大而发生红移;该纳米晶质量很高,具有很强的发光能力,其发射光谱对称的形状和合理的Stokes频移（13 nm）显示,该纳米晶的发光完全出自带隙,没有来自缺陷的发光。此外,实验结果表明,通过改变三辛基亚磷酸的浓度可以调节成核和生长的快慢,从而可以在不同的反应时间得到不同尺寸的单分散性CdSe纳米晶。