The aim of this research is to produce materials that will be useful in complex applications such as nuclear reactor core, fuel rods especially in Gen-IV reactors which operate at higher temperatures than the present reactors, as well as in waste immobilization, high temperature, stress and fatigue applications which are tolerant to a number of radiation fluencies over a period of time. 10 g samples of five different polycrystalline compounds which includes Y₄Zr₃O₁₂, Y₄Hf₃O₁₂, Yb₄Zr₃O₁₂, Yb₄Hf₃O₁₂ and Sc₄Hf₃O₁₂ were produced using conventional ceramic process by solid state sintering for 7days at 15000C in high temperature-furnace with a 50C/min ramp up and down. Three of the samples Yb₄Zr₃O₁₂, Yb₄Hf₃O₁₂ and Sc₄Hf₃O₁₂ were found to be characterized by an ordered, fluorite derivative structure called delta (δ) phase while the other two, Y₄Zr₃O₁₂ and Y₄Hf₃O₁₂ has fluorite phase structure. An in-situ ion beam irradiation experiment was performed on the polycrystalline δ-phase compound with stoichiometry Yb₄Hf₃O₁₂ by Transmission Electron Microscopy (TEM) process. The machine was operated at 200 kV with a light 6 keV He⁺ ions to a maximum fluencies of 1.3 x 10¹⁷ ions/cm² to study the radiation damage in the sample. The sample was prepared for TEM by crushing the pellet into powder using isopropanol and collecting the suspension on carbon coated copper grid. The irradiation was performed from room temperature to 6000C respectively. TEM resolvable gas bubbles were observed which seem to be identical to thermally induced at a temperature of 3000C-5500C in the compound. The result suggests that He⁺ is retained during irradiation, but requires heat to form bubbles. This structural observation in the δ-phase composition can be used to understand the radiation damage effects.

Randomly mixing ferromagnetic (FM) and antiferromagnetic (AFM) elements in high-entropy alloys (HEAs) can create fluctuating local magnetic moments that influence the energetics of point defects. In this study, we employed first-principles calculations to investigate the influence of magnetic properties on vacancy migration energy in Fe49.5Mn29.4Co10.1Cr10.1C0.9, alongside equiatomic NiCoFeCrMn alloy. By examining structures with paramagnetism, ferromagnetism, and no spin polarization, our study reveals significant impacts of magnetic interactions on vacancy migration barriers, potentially altering the sequence of elemental migration energies if overlooked. In Fe49.5Mn29.4Co10.1Cr10.1C0.9, the order of vacancy migration barriers is Co > Fe > Mn > Cr across all magnetic states, suggesting the dominant roles of atomic properties and inherent chemical bonding. Conversely, the NiCoFeCrMn HEA exhibits a pronounced magnetic state-dependent elemental migration energy order, indicating that magnetic interactions significantly influence vacancy migration behavior in this alloy. In addition, while FM elements generally exhibit higher migration barriers, AFM elements display lower barriers in the investigated Cantor alloys, with notable variations between the studied compositions. These findings underscore the critical role of magnetism in accurate migration energy calculations, which is important for studying chemically biased diffusion and radiation-induced segregation in HEAs.