Evolution of percolation properties in nanocomposite films during particle clustering

This paper describes the simulation of the effect of nanoparticle clustering on percolation behaviour in a thin polymeric film containing an inhomogeneous distribution of nanoparticles. A monotonic increase in nanoparticle clustering as composite micro-geometry relaxed resulted in the formation of a percolating network followed by a transition to compacted clusters of nanoparticles and a reduction in the percolative flux. Over longer time-scales, coarsening of clusters was dominated by changes in cluster surface morphology and the through thickness flux increased steadily. © 2006 Acta Materialia Inc

The effect of inhomogeneities in particle distribution on the dielectric properties of composite films

A practical approach for the modelling of the dielectric constants of thin composite films is presented. A general distribution function for composition fluctuations in the thin composite films is introduced to describe the transition from a non-percolative to a percolative morphology using physically meaningful parameters and is applied to model a wide range of experimental and simulated polymer-ceramic composite film behaviour from the literature, up to ceramic particle filler volume fractions of 75%. The parameters describing the morphologies of the various composites are used to predict effective dielectric properties with good accuracy. The model is applied further to composites that show early percolation behaviour, and the deviation of their effective dielectric behaviour from the standard effective medium theory at high filler volume fractions is discussed. © 2006 IOP Publishing Ltd

Surface acoustic wave device design for gas sensing applications

A dual delay line surface acoustic wave device designed for gas sensing applications is described. The viability of this design is demonstrated using data showing the response to NO/sub 2/ with a sensitising layer of lead phthalocyanine