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Cover Picture: Strength of metals at the Fermi length scale (Phys. Status Solidi RRL 3/2012)
Author(s) -
Armstrong Jason N.,
Hua Susan Z.,
Chopra Harsh Deep
Publication year - 2012
Publication title -
physica status solidi (rrl) – rapid research letters
Language(s) - English
Resource type - Reports
SCImago Journal Rank - 0.786
H-Index - 68
eISSN - 1862-6270
pISSN - 1862-6254
DOI - 10.1002/pssr.201290003
Subject(s) - crystal (programming language) , ideal (ethics) , atom (system on chip) , materials science , physical property , fermi level , property (philosophy) , condensed matter physics , geometry , mathematics , physics , quantum mechanics , composite material , law , computer science , programming language , philosophy , epistemology , political science , embedded system , electron
The measured strength of real crystals is often 1,000–10,000 times lower than the theoretical or ideal strength of defect‐free crystals. In their Letter on pp. 99–101 , Armstrong, Hua and Chopra show that by deforming gold and silver samples as small as a single‐atom bridge, the strength of defect‐free metals approaches ideal values, yielding stresses that are over 10,000 times higher than in bulk crystals. These results also provide direct evi‐dence for Pauling's prediction of bond stiffening with reduced atomic coordination. The study further shows a re‐markable emergent characteristic of an intensive physical property as the size of the crystal is increased from a single atom to bulk – the property (strength) evolves in a staircase manner as opposed to the intuitively assumed con‐tinuous approach to a saturating bulk value. The observed variation in strength with size retains the inherent trait of an intensive property in the form of size‐independent staircase plateaus. The plateaus can be explained by necessary geometric configurations that atoms assume as the crystal grows in size. Each plateau consists of a finite number of atomic configurations resulting from successive atoms sitting at equivalent energy sites. With increase in size, the number of possible sites increases rapidly and the plateaus eventually give way to size‐independent bulk behavior expected for an intensive property.