Response of non-stoichiometric pyrochlore composition Nd_1.8Zr_2.2O_7.1 to electronic excitations

Pyrochlore oxides are having extensive excellent physical and chemical properties which make them most relevant candidate for various technological applications; namely, high-temperature thermal barrier coating material, nuclear waste matrix material and inert matrix fuel, catalysts, and solid electrolytes, etc. In the view of their application in nuclear industry, the radiation tolerance of pyrochlore materials is decided by compositions, structure-symmetry, microstructure, bond energy, bond-type, ion fluence, melting, grain size, and re-crystallization temperature. In this experiment, the effect of non-stoichiometry in Nd₂Zr₂O₇ is explored as a new parameter to control its radiation tolerance. In response of swift heavy ion (100 MeV I⁷⁺) irradiation, the irradiation induced disordering in non-stoichiometric pyrochlore composition (Nd_1.8Zr_2.2O_7.1) was investigated through X-ray diffraction and High-resolution transmission electron microscopy compared to that of stoichiometric composition Nd₂Zr₂O₇ having same A³⁺ and B⁴⁺ cations. Both compositions with single-phase pyrochlore superstructure (examined by XRD and Raman spectroscopy) exhibits the irradiation induced pyrochlore to anion-deficient fluorite structure transformation along with transformation from pyrochlore to amorphous structure at low fluence. In the wake of irradiation at successive high ion fluences, irradiation caused pyrochlore to amorphous phase transformation was observed in both compositions except the slower rate of amorphization in Nd_1.8Zr_2.2O_7.1