Impact of the R and Mg on the structural, hydrogenation and magnetic properties of R3-XMgXCo9 (R = Pr, Nd, Tb and Y) compounds

Vitalii Shtender (1, 2, 3) , Valérie Paul-Boncour (1) , Roman Denys (4) , Daniel Hedlund (5) , Peter Svedlindh (5) , Ihor Zavaliy (3)

1 ICMPE - Institut de Chimie et des Matériaux Paris-Est
2 Uppsala University
3 Karpenko Physico-Mechanical [ Lviv]
4 HYSTORSYS AS
5 Department of Chemistry – Ångström Laboratory

R2MgCo9 (R = Pr, Nd, Tb and Y) compounds have been synthesized by a powder sintering method and the corresponding hydrides have been prepared by a solid gas method. Their crystal structures and magnetic properties have been systematically studied. X-ray diffraction analysis showed that all R2MgCo9 compounds belong to the PuNi3-type structure. The elements Tb, Y, Nd, Pr yield a lowering of the equilibrium pressure which correlates well with the increase in cell volume. The R2MgCo9H(D)x (R = Pr, Nd, Tb and Y; (9.4 ≤ x ≤ 12)) hydrides (deuterides) preserve the PuNi3-type structure with hydrogenation-induced volume expansion ranging from 14.7 to 19.6%. The substitution of deuterium for hydrogen in R2MgCo9–(H,D)2 (R = Tb and Y) prevents fast desorption at room temperature and ambient pressure. As for the magnetic properties, all the studied intermetallic compounds show ferromagnetic or ferrimagnetic behavior, and in some cases a temperature dependent spin reorientation. Hydrogen insertion reduces the magnetization and decreases the magnetic ordering temperature (TC), whereas Mg for R substitution increases TC.

Mots clés: Rare earth compounds; Magnesium compounds; Metal hydrides; Crystal structures; Magnetic properties

Domaines: Matière Condensée [cond-mat]; Chimie inorganique; Matériaux; Cristallographie

Vitalii Shtender, Valérie Paul-Boncour, Roman Denys, Daniel Hedlund, Peter Svedlindh, et al.. Impact of the R and Mg on the structural, hydrogenation and magnetic properties of R3-XMgXCo9 (R = Pr, Nd, Tb and Y) compounds. Materials Research Bulletin, 2022, 156, pp.111981. ⟨10.1016/j.materresbull.2022.111981⟩. ⟨hal-03795571⟩