VALENCE EFFECT ON THE INCORPORATION OF TUNGSTEN IMPLANTED INTO LITHIUM-NIOBATE

Single crystals of congruent X-cut lithium niobate (LiNbO3) and Mg-dop ed (5 mol% MgO in melt) Z-cut lithium niobate were implanted with 100 keV W+ ions at room temperature to a fluence of 5x10(14) cm(-2), The s amples were annealed in a conventional furnace under flowing wet oxyge n in two steps, first at 600 degrees C for 1 h and subsequently at 850 degrees C for 4 h in order to anneal the layer amorphized by the impl antation. Rutherford Backscattering (RES) angular scans were performed for different axial directions for Nb and W. Far the congruent sample the lattice position of W was unambiguously determined to be the Nb s ite. The influence of the valence of tungsten on the incorporation int o lithium niobate is discussed. On the other hand, for the Mg-doped sa mple the persistence of lattice damage after annealing did not enable a definite determination of the lattice site.