LATTICE SITE LOCATION OF IRON IN POTASSIUM NIOBATE

The lattice site of iron in potassium niobate has been investigated by channeling of He-ions in combination with simultaneous Rutherford backscattering analysis (RBS), nuclear reaction analysis (NRA) and particle induced X-ray emission (PIXE). He-ions with energies of 3.1 MeV were used at the Dynamitron accelerator of the university at Stuttgart. Oxygen was detected by the resonant O-16(alpha,alpha)O-16 nuclear reaction at 3.05 MeV. Two crystals containing 0.12 mol% iron cut perpendicular to the [100] and [110] axis directions according to the cubic configuration of the lattice have been examined. Angular PIXE yield profiles of axial channeling close to the [100], [110], [111] and [221] axes have been compared for iron, niobium and potassium. Also computer simulations have been performed and compared with the measured data. Close resemblance between the angular yield profiles for K and Fe has been found. Therefore we conclude that Fe occupies K lattice sites in Fe:KNbO3. This result is also supported by computer simulations.