Hasil untuk "Property"

A. Huguet, L. Vacher, Stéphane Relexans et al.

S. Stankovich, D. Dikin, G. Dommett et al.

J. Tauc, R. Grigorovici, A. Vancu

The optical constants of amorphous Ge are determined for the photon energies from 0.08 to 1.6 eV. From 0.08 to 0.5 eV, the absorption is due to k-conserving transitions of holes between the valence bands as in p-type crystals; the spin-orbit splitting is found to be 0.20 and 0.21 eV in non-annealed, and annealed samples respectively. The effective masses of the holes in the three bands are 0.49 m (respectively 0.43 m); 0.04 m, and 0.08 m. An absorption band is observed below the main absorption edge (at 300 °K the maximum of this band is at 0.86 eV); the absorption in this band increases with increasing temperature. This band is considered to be due to excitons bound to neutral acceptors, and these are presumably the same ones that play a decisive role in the transport properties and which are considered to be associated with vacancies. The absorption edge has the form: ω2ϵ2∼(hω−Eg)2 (Eg = 0.88 eV at 300 °K). This suggests that the optical transitions conserve energy but not k vector, and that the densities of states near the band extrema have the same energy-dependence as in crystalline Ge. A simple theory describing this situation is proposed, and comparison of it with the experimental results leads to an estimate of the localization of the conduction-band wavefunctions.

G. Wilk, R. Wallace, J. Anthony

J. L. Abascal, C. Vega

C. Rice-evans, N. Miller, G. Paganga

M. Cossi, N. Rega, G. Scalmani et al.

A. Alivisatos

G. Schatz, K. Kelly, E. Coronado et al.

M. Staiger, A. Pietak, Jerawala Huadmai et al.

J. Stewart

A. Bledzki, J. Gassan

R. Hill

R. Boyer, G. Welsch, E. Collings

J. Rho, L. Kuhn-Spearing, Peter Zioupos

Detailed descriptions of the structural features of bone abound in the literature; however, the mechanical properties of bone, in particular those at the micro- and nano-structural level, remain poorly understood. This paper surveys the mechanical data that are available, with an emphasis on the relationship between the complex hierarchical structure of bone and its mechanical properties. Attempts to predict the mechanical properties of bone by applying composite rule of mixtures formulae have been only moderately successful, making it clear that an accurate model should include the molecular interactions or physical mechanisms involved in transfer of load across the bone material subunits. Models of this sort cannot be constructed before more information is available about the interactions between the various organic and inorganic components. Therefore, further investigations of mechanical properties at the 'materials level', in addition to the studies at the 'structural level' are needed to fill the gap in our present knowledge and to achieve a complete understanding of the mechanical properties of bone.

C. Gabriel, S. Gabriel, E. Corthout

S. Nemat-Nasser, M. Lori, S. Datta

E. Fix, J. Hodges

Marcel J. M. Pelgrom, A. Duinmaijer

B. Shklovskii, A. Efros