Deuterium retention in tungsten trioxide irradiated with D ions

The depth profiles of deuterium trapped as D atoms and D, molecules in WO3 films both exposed to D plasma at temperatures in the range from 300 to 650 K and implanted with 10 keV D ions at 300 K and 650 K respectively have been determined by means of secondary ion mass spectrometry and residual gas analysis. After plasma exposure at 350-550 K and ion implantation at 300 K, most of the deuterium is accumulated as D-2 molecules. The appearance of molecular deuterium in the D implanted WO3 film is considered to be related to the formation of cavities filled with deuterium. D atoms seem to be chemically bonded to O atoms forming deuterium tungsten bronze and captured by grain boundaries. Further irradiation with 10 keV D ions at both 300 K and 650 K leads to the reduction of WO3 to metallic W within the ion stopping zone.