Microstructure of dysprosium hafnate after sequential irradiation with heavy and light ions

The paper presents the results of a study on the microstructure of dysprosium hafnate $0.5 \text{Dy}_{\text{2}} \text{O}_3 0.5\text{Hf} \text{O}_2$ after irradiation with heavy and light ions. Tablet samples of the studied material were prepared using traditional powder metallurgy methods (pressing a powder mixture followed by sintering at $1800^{\circ} \text{C}$). Irradiation was carried out sequentially (5 cycles) with $\text{Ni}^{4+}$ ions with an energy of 11.5 MeV and $\text{He}^{+}$ ions with energies of $0.8 - 1.4$ MeV to damaging doses of $20-300$ dpa and helium content of 84 appm He/dpa at $350^{\circ}\text{C}$ and $550^{\circ}\text{C}$. The microstructure was studied using transmission electron microscopy. It has been revealed that radiation-induced porosity is formed in all the studied samples, with the size of pores/bubbles slightly increasing in size and density with increasing the dose and irradiation temperature. The maximum swelling was observed in the sample irradiated up to 300 dpa at $550^{\circ}\text{C}$. The swelling of all samples remains within 0.1\%, which indicates the high radiation resistance of dysprosium hafnate.