The lattice contraction of UO2 from Cr doping as determined via high resolution synchrotron X-ray powder diffraction

High resolution synchrotron powder X-ray diffraction analysis of Cr-doped UO2 powder samples with additions of Cr2O3 as 0, 500, 1000, 1500, 2500 to 3500 ppm that were prepared under sintering conditions of -420 kJ/mol and 1700 oC is reported. The lattice dependence of Cr doping is precisely established through the Rietveld method where the rate of linear lattice parameter contraction from Cr doping, Δacr, was found to be considerably smaller and much more subtle than previously described by literature. This investigation demonstrates the critical need for high resolution and precise specimen preparation when experimentally measuring and interpreting results from subtle changes to nuclear fuel material crystal structures due to trace doping.