First-principles studies on band structure and mechanical properties of BiFeO3 ceramics under high pressure

Mechanical properties and band structure of rhombohedral BiFeO3 nanostructures were studied using density functional theory for different pressures in the range from 0 to 50GPa. The elastic constant of BiFeO3 nanoceramics was determined and different moduli were calculated for various applied pressures. The bulk (B) and shear (G) modulus show an increasing trend on applied high pressure. The findings of the present work also confirm that the hardness of BiFeO3 increases with the applied pressure. The ductility of BiFeO3 nanostructure increases upon increasing the pressure, which is confirmed from Poisson’s ratio and B/G ratio. The band structure studies were also carried out under high pressure and showed that the band gap decreases upon increase in the applied pressure

Magnesium ferrite nanostructures for detection of ethanol vapours - A first-principles study

The adsorption behaviour and electronic properties of ethanol vapour on MgFe2O4 ceramic nanostructures are studied using density functional theory technique. The structural stability of MgFe2O4 nanostructure is determined with the help of formation energy. The adsorption behaviour of ethanol molecules on MgFe2O4 base material is analysed in terms of average energy gap variation, Mulliken charge transfer, band gap and adsorption energy. The most prominent adsorption sites of ethanol vapours on MgFe2O4 nanostructure are investigated at atomistic level. The density of states spectrum reveals the clear picture about the electronic properties of MgFe2O4 nanostructure. The density of states and electronic band gap confirmed the adsorption of ethanol vapours on MgFe2O4 nanostructure. The changes in the energy band gap and density of states are observed upon adsorption of ethanol vapour molecules on MgFe2O4 nanostructure. The density of states spectrum also confirms the changes in peak maxima due to the transfer of electrons between MgFe2O4 nanostructure and ethanol vapours. The adsorption of oxygen atom from ethanol vapour on iron in MgFe2O4 is found to be more prominent rather than other adsorption sites. The findings show that MgFe2O4 nanostructure can be utilized to sense the presence of ethanol vapour in the atmosphere

Mesoporous and hexagonally ordered CuAl-SBA-15-catalyzed tandem C-C and C-O bond formation between phenols and allylic alcohols

A novel mesoporous catalyst, CuAl-SBA-15, with a hexagonally ordered porous structure prepared via a soft-templating approach in a highly acidic medium is used for tandem C-C and C-O bond formation between phenols and allylic alcohols to afford a variety of dihydrobenzopyrans in good yields. The catalyst is also found to be highly active for the synthesis of vitamin E and can be recycled several times without significant loss of its activity