Ion irradiation experiments and quantitative x-ray diffraction analysis were used to demonstrate that the lattice and structure behave very differently in a complex oxide, δ-Sc 4 Hf 3 O 12 , under irradiation. Analysis of the structure reveals that with increasing fluence, the characteristic c/a ratio for the δ phase converges to that of an ideal fluorite phase, whereas locally it produces a metaphase consisting of frozen nanoscale structures having bixbyite-like flavor that increase the overall stability and radiation response of the apparent long-range oxygen-deficient average fluorite structure.