Peculiar thermal expansion induced by enhanced Fe interaction in (Ti,Zr)Fe2+x alloy

In the (Ti,Zr)Fe2+x system, we further break through the stoichiometric ratio limit of AB2 type alloys by supercritical quenching (rapid cooling with liquid nitrogen), which may reverse part of Fe to the original 4f position occupied by non-magnetic elements and enhance the magnetic volume effect (MVE). Finally, we obtained the widest near zero thermal expansion (ZTE) temperature range (within 523K) of the system. Due to the similar atomic numbers of Ti and Fe in the sample, high intensity X-rays do not distinguish them well. However, the bound coherent scattering lengths of Ti (-0.35×10-12 cm) and Fe (0.95×10-12 cm) are significantly different, so neutron powder diffraction is a powerful means to distinguish between the two elements. In this proposal, we hope to conduct neutron powder diffraction to (i) determine the accurate crystal structures by distinguishing Ti and Fe, (ii) reveal the magnetic structures, (iii) obtain the magnetic moment of Fe as a function of temperatures, which is a critical step to understand the structure-property relationship in these compounds.