Monodispersed Cr cluster formation by plasma-gas-condensation
Monodispersed Cr cluster formation by plasma-gas-condensation
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DOI：
10.1063/1.369476
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发表时间：
1999-01-01
影响因子：
3.2
通讯作者：
Suzuki, K
中科院分区：
文献类型：
--
作者：
Yamamuro, S;Sumiyama, K;Suzuki, K
通过等离子体气体冷凝型团簇沉积装置，结合生长放电溅射技术和惰性气体冷凝技术，已经产生了尺寸范围为7.6 - 13 nm的纳米尺寸的Cr团簇。用透射电子显微镜研究了Ar气压强（P-Ar）和Ar气流量（V-Ar）对Cr团簇尺寸分布的影响。在低P-Ar和低V-Ar气氛下均能形成单分散的Cr团簇。在低P-Ar气氛下，Cr团簇只在液氮冷却的生长区形核和生长，沉积速率较低。另一方面，在高P-Ar下，即使在溅射源附近也形成大量的Cr团簇，并且在溅射源和生长区域之间的宽区域上发生成核和生长。在此条件下，沉积速率相对较高。因此，单分散团簇的形成机制与单分散胶体颗粒的形成机制相似：成核和生长过程明确分离，生长颗粒的凝聚被禁止。在本实验中，这些条件是有效地实现通过使用载气流和液氮冷却的集群生长区域。(C)1999年美国物理学会。[S0021 - 8979（99）03701 - 9].
Nanometer-sized Cr clusters in the size range of 7.6-13 nm have been produced by a plasma-gas-condensation-type cluster deposition apparatus, which combines a grow-discharge sputtering technique with an inert gas condensation technique. We have studied influences of the Ar gas pressure, P-Ar, and the Ar gas flow rate, V-Ar, on the size distribution of Cr clusters by transmission electron microscopy. Monodispersed Cr clusters are formed at both low P-Ar and low V-Ar. At low P-Ar, Cr clusters nucleate and grow only in the liquid-nitrogen-cooled growth region, and the deposition rate is rather low. At high P-Ar, on the other hand, a large amount of Cr clusters are formed even near the sputtering source, and the nucleation and growth occur over a wide region between the sputtering source and the growth region. Under this condition, the deposition rate is relatively high. Consequently, the formation mechanism of the monodispersed clusters is similar to that of monodispersed colloidal particles: The nucleation and growth processes are definitely separated and the coagulation of growing particles is prohibited. In the present experiments, these conditions are effectively attained by using a carrier gas flow and liquid-nitrogen-cooling of the cluster growth region. (C) 1999 American Institute of Physics. [S0021-8979(99)03701-9].