Non-monotonic variation of Curie temperature in (TmxPr1-x)2Fe16.5Cr0.5

• Published in: Journal of alloys and compounds 2019-06, Vol.791, p.225-231
• Main Authors: Kuchin, A.G., Platonov, S.P., Gaviko, V.S., Voronin, V.I.
• Format: Article
• Language: English
• Subjects: Alloy systems; Crystal structure; Curie temperature; Intermetallic compounds; Lattice parameters; Magnetic measurements; Magnetic properties; Magnetism; Phase transitions; Phases; Rare earth alloys and compounds; Strain; Temperature; X-ray diffraction
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2019.03.322

Crystal structure and magnetic and thermomagnetic properties of the (TmxPr1-x)2Fe16.5Cr0.5 system have been studied. The alloys with x = 0–0.4 and x = 0.75–1 crystallize into a rhombohedral structure of the Th2Zn17-type and into a hexagonal structure of the Th2Ni17-type, respectively. Both these structures coexist in the concentration range x = 0.5–0.6. The lattice parameters, spontaneous magnetization, and the peak entropy change -ΔSM of the (TmxPr1-x)2Fe16.5Cr0.5 system decrease with increasing Tm content. The Curie temperature of these intermetallic compounds increases non-monotonically from 331 K to 356 K upon partial substitution of Pr for Tm and demonstrates two local minima at x = 0.4 and 0.8. Maximal microdeformations in the alloy with x = 0.8 have been detected by means of X-ray diffraction. The unusual large difference of 25–28 K between the Curie temperatures of the rhombohedral and hexagonal phases in the two-phases compounds with x = 0.5–0.6 has been obtained. The existence of two Curie temperatures causes the temperature interval with maximal values of magnetocaloric effect to be much larger for the two-phases compositions as compared with the single-phase compounds. [Display omitted] •The Th2Zn17- and Th2Ni17-type phases realize for x = 0–0.4 and 0.75–1, respectively.•Both these structures coexist in the (TmxPr1-x)2Fe17 compounds with x = 0.5–0.6.•Curie temperature TC of these two structures differs on 25–28 K for x = 0.5–0.6.•The temperature interval with maximal MCE is larger for the two-phase compositions.•Maximal microdeformations detected for x = 0.8 can stipulate a local minimum of TC(x).