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Organic and Metallic Glasses: Dynamics, Recrystallization and Vibrational Properties

Total activity: 9
Type of activity
Competitive project
Funding entity
AGENCIA ESTATAL DE INVESTIGACION
Acronym
OMeG-VIP
Funding entity code
FIS2017-82625-P
Amount
145.200,00 €
Start date
2018-01-01
End date
2020-12-31
Keywords
Alta Presión, Amorphous drugs, Dinámica, Dynamics, Estabilidad, Estructura, Fármacos amorfos, High-Pressure, Metallic Glass, Organic Glass, Poliamorfismo, Polyamorphism, Relajación, Relaxation, Stability, Structure, Vidrios Metálicos, Vidrios Orgánicos
Abstract
This project continues the work of two long-experience, complementary and scientifically contrasted research groups working within the
framework of glass-forming (organic and metallic) materials, sharing knowledge and available equipment and strengthening the
international reputation.
The understanding of the behavior of non-crystallizing liquids and the formation of glasses by decreasing temperature (or increasing
pressure) is an unsolved problem currently seen as a major intellectual challenge in condensed matter physics. The initial concept of
glassy state has now been generalized and it is recognized that any system with some kind of disorder (translational, orientational,
conformational, statistical disorder of site occupancy, ) in its ergodic state can give rise to a glassy state, the non-ergodic state (by cooling,
by pressurizing or by other physical methods as vapor deposition) in which the initial degrees of freedom become frozen. The so-reached
amorphous states in simple organic compounds, polymers, ceramics, and metallic systems provide a variety of important materials which
are, in many cases, of widespread use.
The glass transition is a kinetic phenomenon and hence the properties of glasses depend on the thermodynamic path to reach the glass
state. The importance of dynamics, one of the main topics of this project, becomes obvious when considering the usual way of preparing a
canonical glass: a liquid has to be cooled sufficiently fast to avoid crystallization. Thus, the key points for understanding the glass transition
concern the physics behind the continuous and dramatic increase of the shear viscosity, or similarly, the main (collective) structural alfarelaxation
time, the origin of the secondary fast beta-relaxations and the dynamic heterogeneities embedded into the intermediate
scattering function, F_S(q, t), providing a general connection between spatial fluctuations and relaxation kinetics.
Alike crystalline solids share many properties regardless their composition, glasses show very similar responses to different types of
perturbations, independently of the materials details. Such universalities enable us to treat simple molecular compounds or atomic metallic
glass-formers within equivalent physical images and, hence, sharing the knowledge between members of the present group working on
apparently different kind of glass-forming materials.
The project will mainly deepen on the links between the dynamics phenomena and structural features of the canonical (i.e. structural), organic and metallic, glasses (obtained by freezing the whole disorder of the liquid state), orientational glasses (obtained by
freezing the orientational disorder, in plastic phases) and low-dimensional glasses (obtained by freezing the statistical disorder on the site
occupancy in low-symmetry lattices). The influence of pressure in the dynamics of glasses will be one of the differentiating facts with
respect to other research groups. From the use of temperature- and pressure-dependent measurements, it is possible to unravel whether
the molecular dynamics is dominated (limited) by thermal energy or by the available free volume. In addition, combination of both variables
allows disentangling the two competitive driving forces having critical influence on the crystallization process, i.e. kinetics (nucleation and
growth) and thermodynamics (chemical potential difference).

Participants

Scientific and technological production

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