Melting of Pb nanocrystals
Melting of Pb nanocrystals
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DOI：
10.1103/physrevb.57.13430
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发表时间：
1998-06-01
影响因子：
3.7
通讯作者：
Chung, YW
中科院分区：
文献类型：
--
作者：
Peters, KF;Cohen, JB;Chung, YW
超高真空中的 X 射线粉末衍射证明了 Pb 纳米晶体的尺寸依赖性熔化和表面熔化。尽管一些先前的研究通过衍射强度测量了与尺寸相关的熔化温度，但这里表明微晶重新取向使得衍射强度成为不可靠的熔化指标。衍射峰形状代替衍射强度，通过微晶尺寸分布的变化揭示了尺寸相关的熔化。测量表明，熔化温度与微晶尺寸成反比变化，并且在定量上有利于液皮熔化模型而不是均匀熔化模型。表面熔化是通过 0.5 nm 液皮在 50 nm 微晶上的可逆生长来证明的，其温度略低于尺寸相关的熔化温度。
The size-dependent melting and surface melting of Pb nanocrystals is demonstrated by x-ray powder diffraction in ultrahigh vacuum. Whereas some prior studies have measured the size-dependent melting temperature via the diffraction intensity, it is shown here that crystallite reorientation makes the diffraction intensity an unreliable indicator of melting. instead of the diffraction intensity, the diffraction peak shape reveals the size-dependent melting via changes in the crystallite size distribution. Measurements showed that the melting temperature varies inversely with the crystallite size and quantitatively favors the liquid-skin melting model over the homogeneous melting model. Surface melting is demonstrated via the reversible growth of a 0.5 nm liquid skin on 50 nm crystallites just below the size-dependent melting temperature.