Publications de Claudio Grimaldi

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Thick-film resistors (TFRs) consist of a percolating network of conducting oxide nanoparticlesdispersed in an insulating glassy matrix, whose resistive properties are dominated by quantumtunneling across insulating layers separating adjacent conducting grains. Tunneling processes are at the origin of the high sensitivity of the TFRs resistances to applied strains. We have measuredtransport and piezoresistive response for different RuO2-based TFRs as a function of metallic concentration x and RuO 2 grain siz

We report electrical conductivity measurements of polymethyl-methacrylate filled by onion-like carbon particles with a primary particle size of approximate to 5 nm. We show that the conductivity sigma is exceptionally high even at very low loadings and tha ...

We investigate the tunneling-percolation mechanism of DC transport nonuniversality for conducting particles of diameter Φ placed in series within the bonds of length Lof a regular lattice model. When L/Φ→∞ the resulting bond conductance distribution functi ...

The values obtained experimentally for the conductivity critical exponent in numerous percolation systems, in which the interparticle conduction is by tunneling, were found to be in the range of t0 and about t0 + ...

We propose a model of transport in thick-film resistors which naturally explains the observed nonuniversal values of the conductance exponent t extracted in the vicinity of the percolation transition. Essential ingredients of the model are the segregated microstructure typical of thick-film resistors and tunneling between the conducting grains. Nonuniversality sets in as a consequence of wide distribution of interparticle tunneling distances. © 2003 American Institute of Physics.

We show that the formation of a gel by conducting colloidal particles leads to a dramatic enhancement in bulk conductivity, due to interparticle electron tunneling, combining predictions from molecular-dynamics simulations with structural measurements in an experimental colloid system. Our results show how colloidal gelation can be used as a general route to huge enhancements of conductivity, and suggest a feasible way for developing cheap materials with novel properties and low metal content.

Here the electron-phonon Holstein model with Rashba spin-orbit interaction is studied for a two-dimensional square lattice in the adiabatic limit. It is demonstrated that a delocalized electron at zero spin-orbit coupling localizes into a large polaron sta ...

Despite a large amount of data and numerous theoretical proposals, the microscopic mechanism of ransport in thick-film resistors remains unclear. However, recent low-temperature measurements point toward a possible variable-range-hopping mechanism of transport. Here, we examine how such a mechanism affects the gauge factor of thick-film resistors. We find that at sufficiently low temperatures T, for which the resistivity follows the Mott’s law R(T);exp(T0 /T)1/4, the gauge factor ~GF! is proportional to (T0

One of the major goals for astronomy in the next decades is the remote search for biosignatures (i.e., the spectroscopic evidence of biological activity) in exoplanets. Here we adopt a Bayesian statistical framework to discuss the implications of such futu ...

The lack of evidence for the existence of extraterrestrial life, even the simplest forms of animal life, makes it is difficult to decide whether the search for extraterrestrial intelligence (SETI) is more a high-risk, high-payoff endeavor than a futile att ...

For centuries, artisans have harnessed gold nanoparticles to imbue their creations with the vibrant hues that captivate the eye through interactions with visible light. In modern times, these distinct optoelectronic characteristics have pivoted toward the ...

In this work, the properties (sheet-resistance, temperature coefficient and piezoresistance / gauge factor) and stability of thick-film resistors with low firing temperatures (525...650°C) are studied. To this end, two low-melting lead borosilicate glass composition have been chosen, together with RuO2 as a conductive filler. The effect on the properties and stability of composition and firing temperature is studied. The stability of the materials is quantified during high-temperature storage (annealing) at

We show that in RuO2–glass composites the nonuniversal resistivity exponent can be modulated by an applied mechanical strain, signaled by a logarithmic divergence of the piezoresistive response at the percolation threshold. We interpret this phenomenon as being due to a tunneling-distance dependence of the transport exponent, supporting therefore a theory of transport nonuniversality proposed some years ago. © 2004 American Institute of Physics. [DOI: 10.1063/1.1835996]

The lack of detection to date of electromagnetic technosignatures implies either that we have been unable to detect them due to incomplete sampling of the search space or that we cannot detect them because the Earth has been located during the entire histo ...

In this work we seek to better understand the mechanisms governing pulse voltage trimming in disordered conductor-insulator composites. Therefore, we investigate the effect of the composition of thick-film resistors (TFRs) on sensitivity to high voltage pu ...

This paper presents recent work on complete thick-film systems, including dielectrics, conductors and resistors, with a lowered firing temperature range of 450...750°C. These materials allow the extension of proven, reliable and inexpensive thick-film technology to novel applications in electronics and sensors.

To assess the number of life-bearing worlds in astrophysical environments, it is necessary to take the intertwined processes of abiogenesis (birth), extinction (death), and transfer of life (migration) into account. We construct a mathematical model that i ...

We formulate a generalized tunneling-percolation model that describes the electrical properties of conductor-insulator cellular disordered systems. This model predicts and explains the experimentally observed universal and nonuniversal behaviors of such pr ...

Project aim: optimised piezoresistive thick-film compositions, especially for low-temperature applications on aluminum alloys, titanium alloys, steel and glass

Claudio Grimaldi

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Transport nonuniversality and critical behavior of the piezoresistive response in thick-film resistors

Electrical transport in onion-like carbon-PMMA nanocomposites

Apparent nonuniversality in finite segregated tunneling-percolaiton models

Tunneling and nonuniversality in continuum percolation systems

A model of transport nonuniversality in thick-film resistors

Enhanced tunneling conductivity induced by gelation of attractive colloids

Large polaron formation induced by Rashba spin-orbit coupling

Gauge factor of thick-film resistors: Outcomes of the variable-range-hopping model

Quantifying the information impact of future searches for exoplanetary biosignatures

Signal coverage approach to the detection probability of hypothetical extraterrestrial emitters in the Milky Way

Tuning the color of high-karat gold in Au-TiO2 nanoparticle composites all the way to black

Properties and stability of thick-film resistors with low processing temperatures - effect of composition and processing parameters

Strain modulation of transport criticality in RuO2-based thick-film resistors

Upper bounds on technoemission rates from 60 years of "silence"

Comment on "Direct Measurement of the Percolation Probability in Carbon Nanofiber-Polyimide Nanocomposites"

High-Voltage Sensitivity Studies of Model Thick-Film Resistors

Low-temperature thick-film systems for electronic and sensor applications

A birth-death-migration model for life in astrophysical environments

Piezoresistivity and tunneling-percolation transport in apparently nonuniversal systems

Nano grain thick-film pastes for mechanical sensor applications