Structural and magnetic transformations in NdMn2Hx hydrides

X-ray powder diffraction and bulk magnetization measurements were used to study structural and magnetic properties of hydrides NdMn2Hx (2.0 ≤ x ≤ 4.0). The X-ray investigations performed in the temperature range 70–385 K have revealed many structural transformations at low temperatures. In particular, a transformation from the hexagonal to the monoclinic phase and spinodal decompositions were observed. The magnetic behavior of the hydrides is correlated with the structural transitions. A tentative structural diagram is presented. The obtained results are compared with the properties of other cubic and hexagonal RMn2Hx hydrides.

► Full structural phase diagram is presented for the NdMn2Hx (2.0 ≤ x ≤ 4.0) hydrides in the temperature range of 70–385 K.
► For samples x = 2.0, 2.5, and 4.0 a splitting into two phases with different hydrogen concentrations are observed.
► Only for samples with x = 3.0 and 3.5 no spinodal decompositions are detected.
► The effects of hydrogen absorption on structural properties are shown to be reflected in magnetic behavior.
► A huge jump of magnetic ordering temperatures from ∼104 K for host NdMn2 to above 200 K for its hydrides is observed or anticipated.