Temperature-driven directional coalescence of silver nanoparticles.
Temperature-driven directional coalescence of silver nanoparticles.
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DOI：
10.1107/s1600577516002253
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发表时间：
2016-05
影响因子：
2.5
通讯作者：
Shi Yan;Dong-bai Sun;Yu Gong;Yuanyuan Tan;Xue-qing Xing;G. Mo;Zhongjun Chen;Q. Cai;Zhihong Li;Hongying Yu;Zhonghua Wu
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文献类型：
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作者：
Shi Yan;Dong-bai Sun;Yu Gong;Yuanyuan Tan;Xue-qing Xing;G. Mo;Zhongjun Chen;Q. Cai;Zhihong Li;Hongying Yu;Zhonghua Wu
以聚乙烯吡咯烷酮为稳定剂，采用化学还原法制备了纳米银。在25~700℃的温度范围内研究了银纳米粒子的热稳定性行为，并用热重分析方法测量了银纳米粒子的失重。用扫描电子显微镜和高分辨电子显微镜观察了银纳米粒子的形貌和形状变化。利用原位随温度变化的小角X射线散射仪检测了颗粒尺寸随温度的增大情况。用原位变温X射线衍射仪表征了纳米晶尺寸的增大和热膨胀系数的变化。结果表明，在较低温度(500℃)下，连续缓慢和快速向东成熟是纳米颗粒生长的主要方法。可以用四阶段模型来描述整个烧结过程。银纳米颗粒的热膨胀系数(2.8×10~(-5)K~(-1))比块体银的热膨胀系数大30%左右。据我们所知，银纳米晶体的温度驱动定向聚结是首次报道。提出了两种可能的定向聚结机制。这一研究不仅具有重要的学术意义，而且对纳米银的热稳定性具有重要意义。
Silver nanoparticles were synthesized with a chemical reduction method in the presence of polyvinylpyrrolidone as stabilizing agent. The thermal stability behavior of the silver nanoparticles was studied in the temperature range from 25 to 700°C. Thermal gravimetric analysis was used to measure the weight loss of the silver nanoparticles. Scanning electron microscopy and high-resolution transmission electron microscopy were used to observe the morphology and the change in shape of the silver nanoparticles. In situ temperature-dependent small-angle X-ray scattering was used to detect the increase in particle size with temperature. In situ temperature-dependent X-ray diffraction was used to characterize the increase in nanocrystal size and the thermal expansion coefficient. The results demonstrate that sequential slow and fast Ostward ripening are the main methods of nanoparticle growth at lower temperatures (500°C). A four-stage model can be used to describe the whole sintering process. The thermal expansion coefficient (2.8 × 10(-5) K(-1)) of silver nanoparticles is about 30% larger than that of bulk silver. To our knowledge, the temperature-driven directional coalescence of silver nanocrystals is reported for the first time. Two possible mechanisms of directional coalescence have been proposed. This study is of importance not only in terms of its fundamental academic interest but also in terms of the thermal stability of silver nanoparticles.