Microstructure Dependence of Material Properties of Composites

Abstract

Effective material constants of composites depend not only on the material constants of the constituents and on their volume fractions but on the microstructure of the composite, too. A general structure dependent expression is derived for the effective dielectric constant of a binary composite as an example. Explicit results are given for typical microstructures. It is proved that all exactly solvable borderline cases are reproduced.Effektive Materialkonstanten makroskopisch heterogen zusammengesetzter Medien hkngen nicht nur von den Materialkonstanten und den relativen Konzentrationen der einzelnen Bestandteile sondern auch vom Gefuge ab. Es wird ein allgemeiner, strukturabhangiger Ausdruck fur die dielektrische Konstante eines binaren Gemisches abgeleitet, und es werden explizite Resultate fur typische Strukturen angegeben. Es wird gezeigt, daB alle streng losbaren Grenzfalle korrekt reproduziert werden.

Raman spectroscopy of porous and bulk GaP subjected to MeV-ion implantation and annealing

“…This correlates with previous observations and theoretical calculations based on effective medium theory. 4,5,25,26,31 The parameters of the Fröhlich mode are neither influenced by ionimplantation damages nor by subsequent annealing.…”

“…Their frequency and strength strongly depend on the actual morphology ͑shape and size of the micro-structure͒ and on the dielectric constant of the medium filling the pores. 30,31 The large FWHM of the observed Fröhlich mode can be attributed to the pore concentration distributions and to the influence of diffuse scattering effects ( ϷL).…”

Micro-Raman-scattering study of surface-related phonon modes in porous GaP

“…The Fröhlich mode frequency depends on the shape of the microstructure as well as on the concentration and the dielectric constant of the surrounding material. [5][6][7][8] In this work we study the changes in micro-Raman spectra of GaP induced by electrochemical dissolution of bulk material at different anodic current densities in order to explore the properties of the surface-related mode. The influence of local heating caused by the absorption of the probing laser irradiation upon micro-Raman spectra is investigated as well.…”

Raman and IR-Reflectance Spectra of Porous III-V Semiconductor Structures

“…For the interpretation of the measured data an effective dielectric function e eff (w) was derived on the basis of an effective medium theory [13]. The porous structure is considered as a heterogeneous medium, composed from the semiconducting matrix with dielec-208 A. Sarua et al with…”