The metal-to-insulator transition in Li and Al doped Lithium Titanate

This monograph provides supporting evidence for the importance of electronic correlations in Lithium Titanate. In chapter one Transition Metal Oxides and their interesting electric and magnetic properties are introduced. Specially, Lithium Titanate, a superconductor, and Lithium Vanadate, the only known d-electron Heavy Fermion, are introduced. In chapter two a single electron model is introduced for the conducting electrons in Lithium Titanate. The model applies a tight-binding approximation for d-electrons of Ti atoms for the alloyed compound of Lithium Titanate which is a Quantum Site Percolation (QSP) model. In chapters three and four this model is applied to a corner-sharing tetrahedral lattice to examine an alloying-induced metal-to-insulator transition. The numerical results show that this model fails to explain this transition. Finally, in chapter five the electronic interactions have been included using a combination of QSP model and Hubbard model on a corner-sharing tetrahedral lattice. Numerical results based on this model explain relatively accurately this transition which shows the important role of electronic correlations in this class of materials.