Material properties vary with crystal size, claims research team
1 min read
In general, a material's properties – such as electrical conductivity, magnetic properties or melting point – do not depend on size and shape. However, experiments conducted recently by researchers from the Vienna University of Technology (TUV) and the University of Calcutta have shown that some materials demonstrate unexpected behaviour when in the form of tiny crystals.
The research has targeted manganites; a form of manganese oxide. According to TUV's Professor Karsten Held, these exhibit 'completely different' properties when their size is reduced to tiny grains: the manganite crystals studied by the research team are less than 15nm in size. When the material crosses over from large to smaller crystals, the distribution of the electrons changes, as does their energy. This, in turn, changes the electrical and magnetic properties of the crystal. "The phenomenon of quantum entanglement plays a very important role here", says Prof Held. "We cannot think of the electrons as classical particles, moving independently of each other on well separated paths. The electrons can only be described collectively."
By changing granular size, says the team, the properties of the manganite-crystals can now be tailored: larger crystals are insulators and are not magnetic; tiny crystals turn out to be metallic ferromagnets. This is believed to open 'exciting new possibilities', according to the scientists.
