ATOMISTIC AND DFT CALCULATIONS OF THE DEFECT STRUCTURE, ELECTRONIC AND MAGNETIC PROPERTIES OF PURE AND Ti4+ DOPED α- AND γ-LiFeO2

Atomistic and density functional theory (DFT) studies were used to examine the Ti 4+ -doped lithium mono-ferrite -LiFeO2 and -LiFeO2 effect on their structure and physical properties of two polymorphs.Atomistic simulations were performed using the GULP code to calculate the defect energy of the structure of both polymorphs when doped with Ti 4+ .From eleven models of possible point defects for Ti 4+ -doped -LiFeO2 and -LiFeO2, the one where the Fe 3+ ions are substituted by Ti 4+ , ones and half Li + ions are substituted Fe 3+ ones was found to be the energetically most favourable.These defects were found to cluster in the same unit cell slightly increasing lattice parameters with small structural distortion in the -LiFeO2 structure.DFT calculations with CRYSTAL code show the Ti 4+ -doped -LiFeO2 modification to undergo a semiconductor-to-half-metallic transitional with a very small band gap for electron states of alpha electrons spin and no gap for beta ones.The Ti 4+doped -LiFeO2, on the other hand, was found to be metallic and both doped polymorphs exhibit an FM ordering rather than an AFM one.