Basic Chemistry & Physics

Pressure-Induced Amorphization and Distinct Amorphous States of Clathrate Hydrates

PhD: Paulo H. B. Brant Carvalho, Stockholm University (2023)

This project explored the phenomenon of pressure-induced amorphization (PIA) in clathrate hydrates—crystalline compounds in which water molecules form cage-like structures encapsulating small guest species. Through in situ neutron diffraction, the research investigated how mechanical compression at low temperatures transforms these crystalline hydrates into amorphous solids, and how subsequent annealing under pressure produces distinct amorphous states that remain stable upon decompression.

Neutron scattering played a crucial role in resolving the structural changes due to its high sensitivity to hydrogen, enabling detailed comparison between amorphous clathrate hydrates and pure amorphous ice. The results contributed to a generalized understanding of amorphization and amorphous–amorphous transitions in water-based systems, offering new insight into the structural behavior of ice-like materials under extreme conditions relevant to both fundamental physics and planetary science.

Paulo Brant Carvalho earned a BSc in Chemistry from the University of São Paulo, with a strong focus on analytical chemistry and spectroscopy. He completed a master’s degree in the Advanced Spectroscopy in Chemistry European Program, hosted by the University of Lille 1 and Jagiellonian University in Kraków. His master’s thesis focused on Lewis acid sites in zeolites, combining density functional theory modelling with the generation of theoretical XANES spectra to support the interpretation of experimental data.