Thermophysical and mechanical properties of MgO-(Nd1-xYx)2Zr2O7 composite ceramics used for inert matrix fuel

MgO-Nd 2 Zr 2 O 7 (M-NZO) composite ceramics, as a promising material for inert matrix fuel (IMF), can be used to replace mixed oxide (MOX) fuel for consuming plutonium (Pu) storage and minor actinides (MA) in light water reactors (LWRs). In this study, the effect of Y doping and content of MgO on the thermophysical properties and mechanical performances of ω MgO-(1- ω )(Nd 1- x Y x ) 2 Zr 2 O 7 (M-NYZ) composite ceramics were systematically investigated. XRD, Rietveld refinement, and SEM-EDS results demonstrated that the as-prepared M-NYZ samples only consist of magnesium oxide and NYZ pyrochlore two phases, and with uniform element distribution and dense microtopography. In terms of properties, the thermal expansion coefficient and the thermal conductivity of 0.5M-0.5NYZ samples at 100–1200 °C is in the range of 13.1 × 10 −6  K −1 –13.5 × 10 −6  K −1 and 3.9 W⋅m −1 ⋅K −1 –15.9 W⋅m −1 ⋅K −1 , respectively. And the Vickers hardness, Young's modulus, and microhardness of typical samples are located in the range of 8.50–10.10 GPa, 183.35–275.32 GPa, and 7.03–10.52 GPa, respectively. Compared with UO 2 fuel, MOX fuel, and other ceramic IMFs, M-NYZ composite ceramics used for IMF exhibit comparable or even superior thermophysical and mechanical properties.