Size dependency of the elastic modulus of ZnO nanowires: Surface stress effect

Relation between the elastic modulus and the diameter (D) of ZnO nanowires was elucidated using a model with the calculated ZnO surface stresses as input. We predict for ZnO nanowires due to surface stress effect: (1) when D>20 nm, the elastic modulus would be lower than the bulk modulus and decrease with the decreasing diameter, (2) when 20 nm>D>2 nm, the nanowires with a longer length and a wurtzite crystal structure could be mechanically unstable, and (3) when D < 2 nm, the elastic modulus would be higher than that of the bulk value and increase with a decrease in nanowire diameter. (c) 2007 American Institute of Physics.