Ions implanted into TiO2 rutile single crystals: Lattice disorder, lattice site occupation and conductivity

Ions (Au, W, Sb, Hg, Sn, In, Hf,La) with different size mismatch-energies have been implanted at 77 K and 293 K into TiO2. The lattice disorder and lattice site occupation were measured by RBS-C in the [001] and [100] crystalline directions. The conductivity was measured as a function of temperature. For the partially damaged rutile phase recovery was observed below room temperature, in contrast to the amorphous phase. The lattice site occupation is discussed within the solubility rules for equilibrium solid solutions using the electronegativity and the atomic size as coordinates. A large increase of the conductivity sigma was observed with increasing Sb and Sn dose, indicating a saturation behaviour at about 30 Omega(-1) cm(-1). Between 40 K and 293 K In sigma was proportional to T-1/2 for low doses, and proportional to T-1/4 for doses of about 1 x 10(16)/cm(2) and above, indicating that the transport mechanism is due to variable range hopping.