Spin reorientation, normal and inverse magnetocaloric effects in heavy rare-earth iron garnets. Issue 11 (1st August 2020)

• Record Type: Journal Article
• Authors: Li, Canglong; Qiu, Yang; Barasa, Godfrey Okumu; Yuan, Songliu
• Is Part Of: Ceramics international. Volume 46:Issue 11(2020)Part B
• Page Start: 18758
• Page End: 18762
• Publication Date: 2020-08-01
• Subjects: Spin reorientation -- Magnetocaloric effect -- Garnets -- Exchange interaction; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2020.04.191
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: Experiments for heavy rare-earth iron garnets Ho3 Fe5 O12 and Er3 Fe5 O12 show a compensation effect characterized by a near zero magnetization at 134 K and 80 K, respectively. The magnetic entropy change calculated according to the Maxwell's relation is shown to be positive and negative, indicating both normal and inverse magnetocaloric effects exist in the sample. The critical temperature (134 K for Ho3 Fe5 O12, 80 K for Er3 Fe5 O12 ) of the two types of magnetocaloric effect occurs at almost the same temperature as the compensation point. However, the compensation effect is attributed to the multiple exchange interactions among the octahedral sites Fe 3+, the tetrahedral sites Fe 3+ and the dodecahedral sites R 3+, while the reversal of the magnetocaloric effect is originated from the spin reorientation. The maximum magnetic entropy change of the normal magnetocaloric effect is 4.72 J kg −1 K −1 for Ho3 Fe5 O12 at 34 K and 4.94 J kg −1 K −1 for Er3 Fe5 O12 at 24 K, respectively. Moreover, all the positive slopes of basic Arrott plots suggest only the second-order phase transition existing in Ho3 Fe5 O12 and Er3 Fe5 O12 .