The effect of reduced size on the elastic properties measured on silver and lead nanowires and on polypyrrole nanotubes with an outer diameter ranging between 30 and 250 nm is presented and discussed. Resonant-contact atomic force microscopy (AFM) is used to measure their apparent elastic modulus. The measured modulus of the nanomaterials with smaller diameters is significantly higher than that of the larger ones. The latter is comparable to the macroscopic modulus of the materials. The increase of the apparent elastic modulus for the smaller diameters is attributed to surface tension effects. The surface tension of the probed material may be experimentally determined from these AFM measurements.

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Surface tension effect on the mechanical properties of nanomaterials measured by atomic force microscopy

Dynamics at the solid-liquid transition: Experiments at the freezing point

We have studied electrostatic layer-by-layer spraying assembly of inorganic/organic nanocomposite multilayered films consisting of Au nanoparticle (Au NP) and photosensitive polycation nitrodiazoresin (NDR). A uniform growth of the Au NP-based assembly film is revealed by UV−vis spectroscopy and AFM-film thickness measurements. We demonstrate that cross-linked films can be produced by UV irradiation which induces the conversion of originally ionic bonds into covalent ones. The nanostructure of the film such as the thickness and the fraction of Au NP can be tailored by the adsorption conditions. Thus, we find that the mechanical properties, which were measured using a buckling test method, can be tailored to a certain degree.

Au Nanoparticle-based Multilayer Ultrathin Films with Covalently Linked Nanostructures: Spraying Layer-by-layer Assembly and Mechanical Property Characterization

In the Murnaghan approximation, an isothermal relation between pressure (P) and volume (V) for solids is derived from the assumption that the isothermal bulk modulus (B) is a linear function ofP. This paper presents a thermodynamic analysis of a generalized form of the equation, based on treating all its various parameters [viz., V, B, and (∂B/∂P)
 T
 atP=0] as functions of temperature. Extending a previous study, the effect ofT upon (∂B/∂P)

 T
 is accounted for by using a dimensionless parameter introduced by us, which is used in formulating general expressions for the volume dependence of various thermophysical quantities,viz., the thermal expansion coefficient (α), the productαB, and the Gruneisen and Anderson-Gruneisen parameters. Some combinations of these parameters are identified, which show a simple dependence uponP. The new expressions are used in analyzing current approximations and the behavior of the solid in the low-compression range. In particular, an expression forα at highP is reported which generalizes the Anderson equation and previous results by us.

Thermodynamic properties of the generalized Murnaghan equation of state of solids

The extension of the finite strain expansion of the Mie-Gruneisen equation (taking into account the elastic constants in the reference configuration up to the fourth-order) is used to derive the temperature dependence of the volumetric compression and of the second-order elastic adiabatic moduli of cubic solids. Numerical results are given for germanium and silicon and compared to experimental data. Finally, the second pressure derivative of these constants is estimated at zero pressure and 300 K.



L'extension au domaine des deformations finies du modele d'equation d'etat de Mie-Gruneisen (prenant en compte les constantes elastiques dans la configuration de reference jusqu'au quatrieme ordre inclus) permet d'obtenir les variations, en fonction de la temperature, du taux de compression volumique et des modules elastiques adiabatiques du second ordre pour les solides de symetrie cubique. Des applications numeriques sont donnees pour le germanium et le silicium et comparees aux mesures experimentales. Finalement, nous donnons une estimation des derivees secondes des modules effectifs par rapport a la pression, a pression nulle et 300 K.

Gérard Perrin

Papers

Generalized Anderson-Grüneisen parameters for non-cubic solids

Theoretical melting curves for cubic solids at high pressure

On the use of Anderson–Grüneisen parameters in calculation of the temperature derivative of elastic moduli for cubic polycrystals

Theoretical determination of the temperature dependence of elastic properties in cubic polycrystals