Question: Recently researchers from which of the following institutions have discovered Semi-Dirac metals that have some special properties?
(a) IIT Kharagpur
(b) IIT Bombay
(c) IISc
(d) TIFR
Answer: (b)
Related facts:
- According a research study published in October 2019; Researchers from IIT Bombay have discovered special properties in a class of materials called semi-Dirac metals.
- Prof Bhaskaran Muralidharan and Dr Alestin Mawrie associated to the IIT have researched these specific category of two-dimensional nanomaterials
- Their theoretical studies show that it is possible to engineer semi-Dirac materials to make optical filters and efficient thermoelectric nanodevices.
- This study is published in the journal Physical Review B.
- These semi- Dirac materials are titanium dioxide and Vanadium oxide (TiO2/V2O3) nanostructures.
- The researchers have proved that such materials would be transparent to light of a given frequency and polarisation when it is incident along a particular direction.
- The material would be opaque to the same light when it falls on it from a different direction.
Dirac metals:
- The term Dirac matter refers to a class of condensed matter systems which can be effectively described by the Dirac equation.
- The quality of conduction in normal metals like gold and silver depends on the way energy depends on the momentum of electrons.
- Dirac metals differ from normal metals in that the energy depends linearly on the momentum. This difference is responsible for their unique properties.
- Example: Graphene, topological insulators, Dirac semimetals, Weyl semimetals and liquid Helium-3.
Semi-Dirac Metals:
- Semi-Dirac metals behave like Dirac metals in one direction and like normal metals in the perpendicular directions (since their microscopic structure is different along the two directions).
- Within any material, charge carriers, such as electrons, acquire an effective mass which is different from their bare mass depending on the nature of the material.
- • The effective mass and the number of states available for the electron to occupy when it is excited by an electric field, for example, determine the conductivity and other such properties.
- • This is also true of a semi-Dirac metal. In particular, the effective mass becomes zero for conduction along a special direction.
- • Oxides of Titanium and Vanadium (TiO2/V2O3) are the best examples of semi-Dirac metals
- • Nano size particles of TiO2 and V2O3 have the property to align into the form of Dirac metals.
Application:
• The researchers show theoretically that semi-Dirac materials can display such thermoelectric properties.
• There are many known applications for transparent conducting films – the common example being touch screens used in mobiles.
• The study of thermoelectric dwells on the heat-to electricity conversion efficiency, for which there has been recent and tremendous interest due to the advent of nanomaterials and quantum materials.
• Thermoelectricity is a clean energy technology that uses waste heat to produce electricity typically in low power applications.
Links:
https://www.thehindu.com/sci-tech/science/new-class-of-quantum-materials-for-clean-energy-technology/article29807363.ece
https://researchmatters.in/news/new-possibilities-nano-sized-optical-filters