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Zero thermal expansion (ZTE) materials, particularly metals, have important applications in precision manufacturing. Here, ultra-low thermal expansion over a significantly broadened temperature interval is realized by tuning Gd content in ferrimagnetic(FIM) Gd x (Dy 0.5 Ho 0.5) 1-x Co 2 compounds. The achieved coefficients of thermal expansion α l ~+1.3 × 10−6K−1 (5-220K), -1.5 × 10−6K−1 (220-280K) for x=0.5 are even better than the well-known ZTE Invar alloy Fe 0.65 Ni 0.35 , while the operation temperature interval is much wider. The origin is closely related to the regulation of magnetostrictive process by rare earth ions along c-axis in the rhombohedral FIM structure. Our work highlights the advantageous ways to generate ultra-low thermal expansion in magnetocaloric materials. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The Accelerator-Driven Subcritical system (ADS) is a subcritical reactor driven by the spallation neutrons generated in a spallation target under the bombardment of proton beam from an accelerator. To study ADS neutronics, the external spallation neutrons should be investigated carefully for coupling with a reactor core. This work focuses on the investigation into the OpenMC calculations by using different nuclear data libraries coupling with different high-energy Monte Carlo programs such as PHITS, FLUKA, and GEANT4 for ADS neutronics simulation. MCNPX direct calculations is performed as the baseline to compare to coupling-calculations. Firstly, the information of leaking neutrons from a spallation target are calculated with different codes and physical models to evaluate difference from the direct calculations to the coupling-calculations. Secondly, the neutronics characteristics of OECD-ADS model are calculated by using OpenMC calculations coupling with a surface-source from three high-energy codes to compare to MCNPX direct calculations. The neutronics parameters of mono-energy neutron for OECD-ADS evaluated from OpenMC and MCNPX with ENDF/B-VII.0 data library or only from OpenMC with different libraries are found to be in good agreement. The effect of high-energy neutrons is evaluated to be difference of around 25% in beam requirements by MCNPX direct calculations with INCL model and PHITS-OpenMC coupling-calculation with ENDF/B-VII.0 below 20 MeV. The differences in beam requirements between different coupling-calculations with the same library are compared. Moreover, the discrepancies in beam requirements from PHITS-OpenMC with JENDL-4.0/HE from 20 MeV to 200 MeV are around 15%. Finally, both neutron profiles and neutron spectra from coupling-calculations agree well with these from MCNPX direct calculations outside the coupling region of target. • Evaluation of ADS neutronics with different code. • Evaluation of nuclear data affecting on the ADS neutronics. • Evaluation of high-energy neutron affecting on beam requirements in ADS study. • External source efficiency of mono-energy neutrons for spallation neutron source of ADS. • Evaluation of the direct calculation and the external source coupling-calculation in ADS study. [ABSTRACT FROM AUTHOR]