Scientists propose a new measure of flexibility for crystals

Sub: Science and tech

Sec: Msc

Context:

Professor Umesh V. Waghmare from the Theoretical Sciences Unit at Jawaharlal Nehru Centre for Advanced Scientific Research, (JNCASR) Bengaluru and his team recently introduced a novel quantitative measure of mechanical flexibility for crystals that can be used to screen materials databases to identify next-generation flexible materials.

More on news:

Researchers have carried out an in-depth analysis of the mechanisms underlying the flexibility of crystals of Metal-organic frameworks (MOFs) and attributed the flexibility to large structural rearrangements associated with soft and hard vibrations within a crystal that strongly couples to strain fields.

About Metal-organic frameworks (MOFs):

Metal-organic frameworks (MOFs) are a large class of crystalline materials which possess the remarkable ability to absorb gasses, such as carbon dioxide, and store them as well as act as filters for crude oil purification.
MOFs derive their ability from the presence of nanopores, enhancing their surface areas that, in turn, make them adept at absorbing and storing gasses.
However, limited stability and mechanical weakness have hindered their broader applications.
Flexibility in crystals has been assessed in terms of a parameter called elastic modulus, which is a measure of a material’s resistance to strain-induced deformation.
In contrast, this study proposes a unique theoretical measure based on the fractional release of elastic stress or strain energy through internal structural rearrangements under symmetry constraints.
This new metric can be readily calculated using standard techniques of simulation and can rate the flexibility of a crystal on a scale of zero to one, zero signifying the least flexibility while one indicates maximum flexibility.