Local Structure Analysis of ZrN, and Dy0.5Zr0.5N surrogate materials for fast reactor nitride fuel

ZrN is a possible candidate for the diluent material for the nitride fuels containing transuranium elements. Pellets of inert matrix material ZrN, and surrogate nitride fuel material (Dy0.5Zr0.5)N, are fabricated for the purpose of investigating crystal structure. Lattice parameters of (Dy1-xZrx)N followed the Vegards’s low, in spite of large lattice mismatch (~ 7 %) between DyN and ZrN. Local structure analysis was performed by X-ray absorption fine structure and atomic pair-distribution function methods. Although lattice parameter of Dy0.5Zr0.5N is larger than that of ZrN, Zr-N nearest neighbor bond distance of Dy0.5Zr0.5N is shorter than that of ZrN. The complex local structure of DyN and ZrN is related to the preferable effect of ZrN.