by Kim Krieger 胡德良 译
Gold wire thick is enough to hold in your hand bends and stretches, making it useful in electronics equipment. But stretch gold too thin—to less than 20 nanometers in diameter—and it becomes brittle, researchers report this month in Advanced Functional Materials. When the team zoomed in for a closer look at the single-crystal gold wires it had been stretching, it found that the brittle-broken single crystals hadn't been so single when they snapped. They had spontaneously "twinned." Twin crystals share some atoms but their overall crystal structures are offset from each other (as shown by the yellow lines in the picture above). When the gold wires stretch, entire groups of atoms slip into different positions to relieve the stress and create twins. As the gold wire stretches more and more, it twins again and again. It eventually breaks, in a brittle way, along a plane between twins. This discovery may force engineers to treat gold wires in nanoelectronics more gingerly, or substitute a different material entirely. | 如果金线较粗,足可以握在手中,那么它既能弯曲又能拉伸,使其成为电子设备中的有用物料。但是,研究人员在本月《先进功能材料》杂志上报道说,如果把金线拉得过细——直径不到20纳米的话,金线就容易被折断。当研究小组将拉伸的金线放大之后,仔细一看,发现容易折断的单晶金线折断时并非单晶,它们自动变为孪晶。孪晶共同拥有某些原子,整个晶体结构是断错的(见图中的黄线)。当拉伸金线时,整团整团的原子滑到不同的位置上,缓解了压力,产生了孪晶。随着金线被拉伸得越来越细,孪晶的产生也不断地重复着。最终金线很容易地沿着孪晶之间的平面被折断。该发现可能会迫使工程师们在纳米电子学中更加谨慎地处理金线,或者会迫使他们用一种完全不同的材料来替代金线。 |
译自:美国《科学》杂志网站(1 September 2011, 3:11 PM)
原著:Kim Krieger
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