Hyperfine interactions in and lattice parameters of pyrochlore and defect fluorite (Eu1−xNdx)2Zr2O7

Pyrochlore and defect fluorite (Eu1−xNdx)2Zr2O7 compounds (x=0, 0.5 and 0.75) synthesized by a wet chemical approach were investigated using temperature dependent high energy X-ray diffraction as well as 151Eu Mössbauer spectroscopy. Diffraction data reveals an increase in lattice parameter with increasing Nd content, an increase that is disproportionally large between x=0.5 and 0.75. The 151Eu Mössbauer spectral parameters, i.e. isomer shift and quadrupole splitting, fall in separate regions for pyrochlore and defect fluorite type compounds. Between 80 and 350 K, the impact of the order-disorder, i.e. pyrochlore to defect fluorite, transition on isomer shift and quadrupole splitting is found to exceed the one due to lattice expansion.