Chiu Hsiang Wei, Kauzlarich Susan M, Sutter Eli
Department of Chemistry, One Shields Avenue, University of California Davis, Davis, California 95616, USA.
Langmuir. 2006 Jun 6;22(12):5455-8. doi: 10.1021/la053343p.
In situ high-resolution transmission electron microscopy (HRTEM) was used to investigate the effect of heating on an organo-Ge polymer/nanoparticle composite material containing 4-8 nm diameter alkyl-terminated Ge nanoparticles. The product was obtained from the reduction of GeCl4 with Na(naphthalide) with subsequent capping of the -Cl surface with n-butyl Grignard reagent. The in situ HRTEM micrographs show that the product undergoes significant changes upon heating from room temperature to 600 degrees C. Two pronounced effects were observed: (i) Ge nanoparticles coalesce and remain crystalline throughout the entire temperature range, and (ii) the organo-Ge polymer acts as a source for the in situ formation of additional Ge nanoparticles. The in situ-formed Ge nanoparticles are approximately 2-3 nm in diameter. These in situ-formed nanoparticles (2-3 nm) are so dense that, together with the original ones, they build up an almost continuous crystalline film in the temperatures between 300 and 500 degrees C. Above 480 degrees C, melting of the in situ formed Ge nanoparticles (2-3 nm) is observed, while nanoparticles greater than 5 nm remain crystalline. After cooling to room temperature, the 2-3 nm Ge nanoparticles recrystallized.
采用原位高分辨率透射电子显微镜（HRTEM）研究了加热对一种含有直径为4 - 8 nm的烷基封端锗纳米颗粒的有机锗聚合物/纳米颗粒复合材料的影响。该产物通过用萘钠还原四氯化锗，随后用正丁基格氏试剂封端-Cl表面而制得。原位HRTEM显微照片显示，该产物在从室温加热到600℃时发生了显著变化。观察到两个明显的效应：（i）锗纳米颗粒聚结，并且在整个温度范围内保持结晶状态；（ii）有机锗聚合物作为原位形成额外锗纳米颗粒的来源。原位形成的锗纳米颗粒直径约为2 - 3 nm。这些原位形成的纳米颗粒（2 - 3 nm）非常致密，以至于在300至500℃之间的温度下，它们与原始纳米颗粒一起形成了几乎连续的结晶膜。在480℃以上，观察到原位形成的2 - 3 nm锗纳米颗粒发生熔化，而大于5 nm的纳米颗粒仍保持结晶状态。冷却至室温后，2 - 3 nm的锗纳米颗粒重新结晶。
