Abstract
Glass is an ultraviscous liquid that ceases to flow on a laboratory timescale but continues to relax on a geological timescale. Quintessentially, it has become hopeless for humans to explore the equilibrium behavior of glass, although the technology of glass making witness a remarkable advance. In this work, we propose a novel thermodynamic path to prepare a high density amorphous state of matter (carvedilol dihydrogen phosphate) using high pressure. In addition, we provide the impeccable experimental evidence of heterogeneous nature of secondary β-relaxation and probe its properties to understand the various aspects of pressure densified glass, such as dynamics, packing and disorder. These features are expected to provide new horizons to glass preparation and functional response to pharmaceutical applications.
Highlights
Glass is an ultraviscous liquid that ceases to flow on a laboratory timescale but continues to relax on a geological timescale
We investigate the conductivity and secondary relaxation time to compare the dynamic properties of glass formed by conventional and proposed path using carvedilol dihydrogen phosphate (Tg ≈341 K)
As the thermodynamic variable pressure directly acts only on intermolecular distance we expect that different energetic modes in glassy state can be appropriately tuned[25]
Summary
Glass is an ultraviscous liquid that ceases to flow on a laboratory timescale but continues to relax on a geological timescale. Position and dynamics of atoms are frozen by dramatic increase in dense packing, structural relaxation time ταbecomes increasingly long It results to a form of matter that does not flow on the laboratory timescale and transforms to an amorphous state of matter i.e., glass. Note that close to Tg the structure of system lacks periodic distribution of matter, all atoms are not structurally equivalent and energy barrier is not a site specific quantity It naturally suggests the appearance and enhancement of a spatio-temporal distribution of local density, energy barrier, molecular mobility (slow or fast), relaxation time (long or short) and the existence of cooperative dynamic length scales in the system. Note that in glassy state the perturbation in β-process is accommodated through dynamics, packing and disorder, thereby suitable tuning of β-process is expected to provide key answers to the above raised issues
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