Cooling down a liquid below its melting temperature can lead to an amorphous frozen system commonly known as a glass. Despite glasses are common in everyday life, the nature of the glass transition still remains one of the most intriguing unsolved problems of condensed matter physics. In this Thesis the atomic length-scale rearrangements of glassy systems close to the glass transition temperature are explored under equilibrium and non-equilibrium conditions with X-Ray Photon Correlation Spectroscopy (XPCS). In particular, we explore the role of directional stresses on the dynamics in a colloidal glass of silica nanoparticles dispersed in a binary solvent. Our results show that the macroscopic stress stored in this glass relaxes via the cooperative ballistic motion of groups of particles with a characteristic size of the order of ten particle diameters. The role of stresses is further investigated in borate-based glasses, where the dynamics well below the glass transition are dictated by the recently discovered X-ray beam-induced dynamics. We show that these dynamics are related to the topology of the network, with peculiar similarities with the stress-phenomenology observed in colloids and metallic glasses.

Density relaxations across the glass-transition under equilibrium and non-equilibrium conditions / Martinelli, Alessandro. - (2021 Apr 29), pp. 1-158. [10.15168/11572_302591]

Density relaxations across the glass-transition under equilibrium and non-equilibrium conditions

Martinelli, Alessandro
2021

Abstract

Cooling down a liquid below its melting temperature can lead to an amorphous frozen system commonly known as a glass. Despite glasses are common in everyday life, the nature of the glass transition still remains one of the most intriguing unsolved problems of condensed matter physics. In this Thesis the atomic length-scale rearrangements of glassy systems close to the glass transition temperature are explored under equilibrium and non-equilibrium conditions with X-Ray Photon Correlation Spectroscopy (XPCS). In particular, we explore the role of directional stresses on the dynamics in a colloidal glass of silica nanoparticles dispersed in a binary solvent. Our results show that the macroscopic stress stored in this glass relaxes via the cooperative ballistic motion of groups of particles with a characteristic size of the order of ten particle diameters. The role of stresses is further investigated in borate-based glasses, where the dynamics well below the glass transition are dictated by the recently discovered X-ray beam-induced dynamics. We show that these dynamics are related to the topology of the network, with peculiar similarities with the stress-phenomenology observed in colloids and metallic glasses.
XXXIII
2019-2020
Fisica (29/10/12-)
Physics
Monaco, Giulio
no
Inglese
File in questo prodotto:
File Dimensione Formato  
PhD_Thesis_Alessandro_Martinelli_def.pdf

embargo fino al 29/04/2022

Descrizione: Tesi di dottorato
Tipologia: Tesi di dottorato (Doctoral Thesis)
Licenza: Tutti i diritti riservati (All rights reserved)
Dimensione 24.6 MB
Formato Adobe PDF
24.6 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11572/302591
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? ND
social impact