COMPACTION OF TUNGSTEN-OXIDE FILMS BY ION-BEAM IRRADIATION

Evaporated amorphous tungsten oxide films with low densities, deposited on different substrates, have been irradiated with various types of ions of different energies up to 30 MeV, and With fluences up to 10(18) cm-2. Compaction of the films up to nearly the bulk density was observed. No changes of the stoichiometry as determined by various ion-beam analysis techniques were detectable. Raman measurements showed that ion-beam-modified films are also amorphous, but have a different microstructure from as-deposited films. The irradiated films have a higher refractive index than the as-deposited films. A low threshold for the compaction effect of a few times 10(12) ions cm-2 was found, leading to the conclusion that one ion displaces more than 10(5) tungsten oxide molecules.