1/f or flicker noise in cellular percolation systems

摘要: Flicker or 1/f noise is studied in a series of four composite discs, which consists carbon black (ground and unground), graphite, graphite/boron nitride, as the conducting components coating, common insulating matrix talc wax. The measurements were done on side (Φ> Φ c ) critical volume fraction (Φ ), within frequency range 1.2-1001.2 Hz. results are analyzed terms Hooge's empirical formula with voltage exponents y m, respectively. Values obtained 0.97-1.2. Samples larger (Φ-Φ have m2, while those smaller m significantly lower than 2. normalized at 10 Hz (S v 1 0 H z /V obey well-established relationships S ( f - k R w , where V across sample resistance R, k, exponents. However, change value exponent was observed measured systems, taking values ∼0.75-5.23 close to 2 ∼2.23-5.54 further into region. from 0.36-1.37, ∼0.99-1.59. (w when < nonuniversality regimes interpreted due superposition behavior that geometry (a random voidlike structure) resulting presence non-Ohmic, intergranular contacts between grains. These tested for consistency using = k/t, compared predictions recent theoretical models.