Swelling and thermal diffusivity changes in neutron-irradiated ceramics

Fifteen forms of ten oxide, nitride, or oxynitride materials were irradiated in EBR-II to 2.8 x 1021 n/cm2 (E/sub n/ > 0.1 MeV) at 10150K (7400C). Of these materials, only those based on Al2O3 or BeO showed volume swelling >0.5%. Ceramics based on MgAl2O4, Y3Al5O12, Y2O3, Si3N4, sialon, and Si2ON2 exhibited 0 to 0.5 vol% swelling. Most of these materials underwent large thermal diffusivity reductions, of the order of 30 to 70%. Single-crystal spinel was notable in displaying almost no damage, as evidenced by lack of changes in volume or thermal conductivity, or defects visible by TEM