Search results for " PROPRIETA'"
showing 4 items of 4 documents
Thermally Induced Structural Modification of Silica Nanoparticles Investigated by Raman and Infrared Absorption Spectroscopies
2010
We report an experimental investigation by Raman and infrared (IR) absorption spectroscopies on the structural modifications induced by isochronal thermal treatments on amorphous SiO2 nanoparticles (fumed silica). In particular, three different commercial types of this material, characterized by particle mean diameters of 7, 14, and 40 nm, were subjected to thermal treatments from 100 up to 1000 °C. We found that some properties of fumed silica, such as the SiOSi mean bond angle, ring size distribution, and surface adsorbed water content, are drastically different from those of common bulk silica materials and intimately related to the particles' dimension. The SiOSi mean bond angle, probed…
Structural properties of the range-II- and range-III order in amorphous-SiO2 probed by electron paramagnetic resonance and Raman spectroscopy
2010
In the present work we report an experimental investigation by electron paramagnetic resonance spectroscopy on the hyperfine structure of the E. point defect, probing the local arrangement of the network (range-II order), and by Raman spectroscopy on the D 1 and D 2 lines, probing mean features of the network (range-III order). Our studies, performed on a-SiO 2 samples thermally treated at 1000 °C in air for different time durations, show that changes of the hyperfine structure and of the D 1 and D 2 lines occur in a correlated way. These results give strong evidence that the range-II and range-III order properties are intimately related to each other and that these properties are determine…
Modification of Ce oxidation state by thermal treatments in controlled atmosphere of Ce-Ti-Eu doped SiO2 glasses
2010
Diritto privato dei mercati digitali
2020
Le tecnologie digitali stanno radical- mente trasformando i mercati. Secon- do molti osservatori siamo dinanzi a una vera e propria metamorfosi del ca- pitalismo contemporaneo. Attorno alle informazioni e al loro sfruttamento sorge un’intera economia nella quale i dati costituiscono la risorsa più prezio- sa e il fattore della produzione più im- portante, proprio come il petrolio nel XX secolo. A cambiare sono le modali- tà di produzione, organizzazione e tra- smissione delle informazioni e, di ri- flesso, le caratteristiche di molti beni e servizi. Mentre il gioco competitivo as- sume nei mercati digitali contorni mol- to diversi da quelli tipici dell’economia industriale, il mondo del lav…