Measurements have been made of electrical conductivity and Young's modulus of a set of sintered, submicron, silver-powder beams with occupied volume fractions (/) in the range 0.1 to 0.3. The results show clear evidence for a percolation threshold at f c = 0.062 ±0.01. The conductivity and elasticity critical exponents, measured in the range 0.6^ (/ -/c)//c^4, were t = 2A5 ±0.25 and r = 3.8 ±0.5, in agreement with recent theories and numerical simulations that show r > t, 1.65 < t < 2.2, and r > 3.55 in three dimensions. 05.70.Jk, 72.15.Cz There has been interest in the behavior of the conductivity and elasticity of a percolating system above the percolation threshold and the question of whether the two properties belong to the same universality class as conjectured by de Gennes. 1 The behavior can be described by the exponents t and r where croc (p -p c ) f and KCC (p -p c ) T are the conductivity and elastic modulus, respectively, p is the fraction of bonds or sites occupied, and p c is the percolation threshold value of p. Recent theoretical work 2 " 5 has shown, by taking account of the nonisotropic nature of the elastic interaction between neighbors, that the elasticity exponent r is significantly larger than t and therefore that the two properties belong to two different universality classes. We present experimental evidence that supports this conclusion for a three-dimensional percolation system comprised of sintered, submicron, silver powder.Feng and Sen 2 considered the extreme cases of isotropic and central forces between neighboring occupied sites. The isotropic case reduced to the conductivity problem, whereas the central-force case was quite different with a considerably higher threshold (p CQn > Pc) and a larger exponent. Intermediate cases showed crossover behavior with r > t near /? cen and T ~ t near p c . Kan tor and Webman 3 considered a more realistic model for macroscopically inhomogeneous systems by taking into account the bending of the backbone structures of a percolating system. The result was that the rigidity of the percolating system goes to zero at the same p c as the conductivity but much more quickly because of the softness to bending of the long continuous chains. The model could not account for the rigidity of multiply connected regions and therefore only a lower bound on r was found. The results for three dimensions was that r > 3.55, which compares with the various estimates for t that are in the range 1.65-2.2. 6 Further, Bergman and Kantor 4 used some particular solvable fractal models of the percolation backbone and Feng et al 5 have used numerical simulations on a two-dimensional percolation model with bond-bending forces to show that r > t. The only evidence for a large elasticity exponent in three dimensions is the elasticity of some polymer systems above the gellation threshold; exponents in the range 1.8 to 3.9 were measured. 7 In two dimensions, an experiment in which holes were punched at random on lattice sites through a thin metal plate 8 demonstrated r > t with ...

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Ferroelectric films of PbZr,,Ti,03 (PZT) have been prepared by one and two step MOCVD techniques using an advanced oxide MOCVD tool. The PZT films were deposited onto 6" Pt/Ti/Si02/Si and Si wafers to measure their phase formation, microstructure and ferroelectric properties. It was found that nucleation of the PZT perovskite phase started when the deposition temperature exceeded 55OOC and grain growth dominated at 650°C and above. The grain size of PbZro,,Tio.,03 thin films increased fiom 0.04 pm to 0.3 pm with increasing deposition temperature, but the surface roughness and leakage current also increased. Therefore, in order to obtain dense and homogeneous PZT films that 'have low surface roughness, we have developed a two step MOCVD process. The PZT thin films made by this two step MOCVD process exhibit excellent ferroelectric properties. Typically, 300 nm thick PZT films with a grain size about 0.3 pm have Pr greater than 20 -30 pC/cm2 at 5V, a dielectric constant around 1000, and low coercive field (Ec 50 -70 kV/cm), fatigue rate about 0.4 after lo9 cycles at 5V and leakage current 2 x A/cm2 at 100 kV/cm and room temperature on Pt electrodes. The microstructure and ferroelectric properties of PZT thin films made by both one and two step MOCVD techriiques were also investigated.