Lattice thermal expansions of (Dy, Zr)N solid solutions

ZrN is a possible candidate for the diluent material for the nitride fuels containing transuranium elements. In the present study, ZrN, DyN and their solid solutions (DyxZr1−x)N (x = 0.2, 0.5 and 0.8) as the analogous fuel material, were prepared by powder metallurgical method through the hydrides. Lattice thermal expansions of these nitrides were measured by a high-temperature X-ray diffraction method from room temperature to 1414 K. The average linear thermal expansion coefficients from 293 to 1300 K for these nitrides increased with Dy fraction x from 7.86 × 10−6 K−1 (ZrN) to 9.54 × 10−6 K−1 (DyN). The effects of the impurities and hypostoichiometry on the lattice parameters and thermal expansions are discussed. On the analogy with the results on the composition dependence of the thermal expansion coefficients, the preferable effect of ZrN as the diluent material is suggested.