title: Lattice anharmonicity in defect-free Pd nanowhiskers.
abstract: We have investigated anharmonic behavior of Pd by applying systematic nanoscale tensile testing to near defect-free nanowhiskers offering a large range of elastic strain. We measured size-dependent deviations from bulk elastic behavior in nanowhiskers with diameters as small as ∼30 nm. In addition to size-dependent variations in Young's modulus in the small strain limit, we measured nonlinear elasticity at strains above ∼1%. Both phenomena are attributed to higher-order elasticity in the bulklike core upon being biased from its equilibrium configuration due to the role of surface stresses in small volumes. Quantification of the size-dependent second- and third-order elastic moduli allows for calculation of intrinsic material nonlinearity parameters, e.g., δ. Comparison of the size-independent values of δ in our nanowhiskers with studies on bulk fcc metals lends further insight into the role of length scales on both elastic and plastic mechanical behavior.
authors.affiliation: Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, 19104, USA.
authors.forename: Lisa Y
authors.initials: LY
authors.lastname: Chen
authors.forename: Gunther
authors.initials: G
authors.lastname: Richter
authors.forename: John P
authors.initials: JP
authors.lastname: Sullivan
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Gianola