lithium-fluoride and titanium-dioxide

Our recent experimental results have indicated that titanium dioxide (TiO₂) mixed with LiF crystals show enhanced absorbance of the organic dye methylene blue. Prompted by these findings, in this study we have investigated the electronic properties of the surface of anatase TiO₂(101) modified by a layer of LiF. Density functional theory (DFT) calculations have been carried out within the generalized gradient approximation (GGA) to accurately describe the electronic structure. From the calculation results we find that the addition of a layer of LiF greatly changes the electronic distribution of the surface of TiO2 (101). We believe this is because the close proximity of the layer of LiF to TiO₂(101) facilitates charge polarization on the special O site of the TiO₂surface. This confirms the theory that Li⁺ improves the absorbability of TiO₂ through inducting special O sites on the TiO₂surface.

Topics: Fluorides; Lithium Compounds; Models, Chemical; Titanium

The thermodynamically required redistribution of ions at given interfaces is being paid increased attention. The present investigation of the contact LiF/TiO(2) offers a highly worthwhile example, as the redistribution processes can be predicted and verified. It consists in Li ion transfer from LiF into the space charge zones of TiO(2). We not only can measure the resulting increase of lithium vacancy conductivity in LiF, we also observe a transition from n- to p-type conductivity in TiO(2) in consistency with the generalized space charge model.

Topics: Absorption; Computer Simulation; Fluorides; Ions; Lithium; Lithium Compounds; Membranes, Artificial; Models, Chemical; Models, Molecular; Nanostructures; Particle Size; Semiconductors; Static Electricity; Titanium