Influence of interstitial and substitutional atoms on magnetocaloric effects in RNi compounds

• Published in: Materials chemistry and physics Vol. 264; p. 124455
• Main Authors: Chzhan, V.B., Kurganskaya, A.A., Tereshina, I.S., Karpenkov, A. Yu, Ovchenkova, I.A., Tereshina-Chitrova, E.A., Andreev, A.V., Gorbunov, D.I., Lushnikov, S.A., Verbetsky, V.N.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.05.2021; Elsevier BV
• Subjects: Cryogenic cooling; Cryogenic temperature; Curie temperature; Hydrides; Hydrogenation; Intermetallic compound; Magnetic properties; Magnetocaloric effect; Rare earth compounds; Magnetocaloric effect; Hydrogenation; Intermetallic compound; Curie temperature
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2021.124455

The effects of substitutional and interstitial atoms on the magnetic and magnetocaloric properties are investigated for RNi (R is rare earth) compounds attractive for magnetic solid-state cooling at cryogenic temperatures. We focused on combining weakly and highly anisotropic rare earth compounds and obtained GdxDy1-xNi (x = 0.1 and 0.9) compounds and their GdxDy1-xNiH3 hydrides. We observed a considerable decrease in Curie temperatures (TC) in the hydrides GdxDy1-xNiH3 compared to their parent alloys. The magnetocaloric effect (MCE) values of GdxDy1-xNiHy (y = 0 and 3) in the vicinity of TC were obtained and compared with literature data for the final GdNi and DyNi compounds. The maximum specific isothermal entropy changes -ΔsT at μ0ΔH = 5 T were 14.5, 17, and 17.5 J kg−1K−1 for GdNi, Gd0.9Dy0.1Ni, and Gd0.9Dy0.1NiH3, respectively. For DyNi, Gd0.1Dy0.9Ni, and Gd0.1Dy0.9NiH3, they were -ΔsT = 18, 15.5, and 12.5 J kg−1K−1 at μ0ΔH = 5 T, respectively. -ΔsT(H) in Gd0.9Dy0.1NiH3 at T = TC linearly increased in fields up to 7 T, while Gd0.1Dy0.9NiH3 at T ≥ TC showed a plateau-like magnetocaloric effect at μ0ΔH = 5 and 7 T. The observed effects were explained based on altered exchange and magnetocrystalline interactions in the modified compounds. •New (GdDy)NiH3 hydrides were obtained.•In Dy-rich compounds, the hydrogenation leads to a change of a crystal structure.•Hydrogenation leads to an extremely large reduction of the Curie temperature.•The (GdDy)NiH3 hydrides obey high values of the plateau-like magnetocaloric effect.