Microstructural evolution of the pyrochlore compound Er ₂Ti ₂O ₇ induced by light ion irradiations

In this report, we present results of an irradiation damage study on a pyrochlore compound, Er ₂Ti ₂O ₇. Polycrystalline Er ₂Ti ₂O ₇ was irradiated with 400 keV Ne ²⁺ ions at cryogenic temperature (∼77 K) to fluences ranging from 2 × 10 ¹⁸ to 2 × 10 ¹⁹ ions/m ². Irradiation-induced microstructural evolution was examined using grazing incidence X-ray diffraction (GIXRD) at angles of γ = 0.25°and 3°. It was found that the irradiated Er ₂Ti ₂O ₇ undergoes significant lattice swelling before succumbing to a radiation-induced partial amorphization transformation. Both of the extent of the lattice swelling and the lattice disorder of the Er ₂Ti ₂O ₇ increase with increasing Ne ion fluence prior to partial amorphization. We present here a detailed discussion regarding the nature of the defects responsible for the observed lattice swelling and disorder in Er ₂Ti ₂O ₇.