Key role of the short-range order on the response of the titanate pyrochlore Y2Ti2O7 to irradiation

Ordering and disordering processes in complex oxides strongly influence their physicochemical properties when they are submitted to severe conditions, such as high temperature, high pressure, or irradiation. This paper examines the role played by the local atomic order on the structural stability of ${\mathrm{Y}}₂\mathrm{T}{\mathrm{i}}₂{\mathrm{O}}₇$ pyrochlore submitted to ion irradiation by combining experimental and atomistic computation studies. X-ray absorption spectroscopy at the Ti K edge, molecular dynamics simulations, and calculations using a tight-binding variable-charge model show that the short-range order around Ti atoms in ${\mathrm{Y}}₂\mathrm{T}{\mathrm{i}}₂{\mathrm{O}}₇$ is strongly modified by irradiation. Strong local distortions around Ti defects occur due to a decrease of the Ti coordination number. These local atomic rearrangements trigger the overall amorphization of the compound. These results show that the local short-range order influences the long-range structural stability of complex oxides, thus providing a key feature for the control of the functional properties of these materials.