TEM characterisation of helium platelets in implanted uranium dioxide

Polycrystalline UO2 discs were implanted with 500 keV helium ions at different temperatures (200, 400 and 600 °C) and fluences (1 and 3 × 1016 at cm−2), and further characterised by transmission electron microscopy (TEM). Examinations performed on the more concentrated sample implanted at 600 °C allowed us to observe platelets for the first time in the UO2 material in planes parallel to {111}UO2. A complete study was undertaken in grains oriented along <1 0 0>, <1 1 0> and <1 1 1> directions to determine {1 1 1} variant equivalence on platelet formation. Their features like density and size have been characterised with an appropriate statistic.