Super Deformability and Young's Modulus of GaAs Nanowires

摘要

The mechanical properties and structural behavior of materials under load change significantly when the dimensions of the materials are reduced to micro- or nanoscales. For example, early studies showed that the yield strengths of micrometer-sized whiskers approach their theoretical strength values. Uchic et al. reported that the tensile strength of single crystal metallic pillars with diameters of tens of micrometers increases with decreasing diameter. The tensile ductilities of metallic glasses and NaCl reach 23-45% and 280%, respectively, when their sample dimensions are reduced to the nanometer regime,' although metallic glasses and NaCl are typically brittle with a near-zero tensile ductility. Recent in situ compression tests' on pillar structures fabricated using the focused ion beam (FIB) technique also revealed some novel phenomena, including "mechanical annealing" in Ni single crystals, ultrahigh stress and strain in hollow CdS nanoparticles, and strong size effects on deformation twinning in TiAl single crystals.