Bruno G.F. Eggert , E.K. Delczeg-Czirjak , Øystein S. Fjellvåg , B.C. Hauback , C. Frommen
{"title":"Structure and magnetism of Fe-substituted MnNiSi0.95Al0.05","authors":"Bruno G.F. Eggert , E.K. Delczeg-Czirjak , Øystein S. Fjellvåg , B.C. Hauback , C. Frommen","doi":"10.1016/j.mtla.2024.102321","DOIUrl":null,"url":null,"abstract":"<div><div>MM'X compounds such as MnNiSi<sub>0.95</sub>Al<sub>0.05</sub> are potential candidates for room temperature magnetocaloric cooling prototypes due to a magnetostructural transition occurring between <em>TiNiSi</em> orthorhombic and <em>Ni</em><sub>2</sub><em>In</em> hexagonal structure-types. Here, Fe substituted MnNiSi<sub>0.95</sub>Al<sub>0.05</sub> is synthesized by arc melting and subsequent heat treatment. Mn<sub>1-x</sub>Fe<sub>x</sub>NiSi<sub>0.95</sub>Al<sub>0.05</sub> and Mn<sub>1-y</sub>Ni<sub>1-y</sub>Fe<sub>2y</sub>Si<sub>0.95</sub>Al<sub>0.05</sub> substitutions feature both the <em>TiNiSi</em> and <em>Ni</em><sub>2</sub><em>In</em> structure-types, and undergo martensitic transitions around room temperature, while MnNi<sub>1-z</sub>Fe<sub>z</sub>Si<sub>0.95</sub>Al<sub>0.05</sub> compositions display MgZn<sub>2</sub> and <em>Mn</em><sub>5</sub><em>Si<sub>3</sub></em> hexagonal <em>structure</em>-types. The stronger covalent character induced by Fe substitution impacts the structural transitions, shifting them to room temperature for Mn<sub>0.5</sub>Fe<sub>0.5</sub>NiSi<sub>0.95</sub>Al<sub>0.05</sub> and Mn<sub>0.68</sub>Ni<sub>0.68</sub>Fe<sub>0.64</sub>Si<sub>0.95</sub>Al<sub>0.05</sub>, which undergo transitions during heating at 305 and 302 K, respectively. The orthorhombic structures display anisotropic thermal expansion, and we observe a negative thermal expansion for Mn<sub>0.45</sub>Fe<sub>0.55</sub>NiSi<sub>0.95</sub>Al<sub>0.05</sub> and a null expansion for Mn<sub>0.68</sub>Ni<sub>0.68</sub>Fe<sub>0.64</sub>Si<sub>0.95</sub>Al<sub>0.05</sub>. Finally, density functional theory calculations predict a larger magnetic moment in Mn<sub>0.68</sub>Ni<sub>0.68</sub>Fe<sub>0.64</sub>Si<sub>0.95</sub>Al<sub>0.05</sub>, which is confirmed both from neutron diffraction and macroscopic measurements. However, due to inhomogeneity attributed to the heat treatment condition, Mn<sub>1-y</sub>Ni<sub>1-y</sub>Fe<sub>2y</sub>Si<sub>0.95</sub>Al<sub>0.05</sub> compounds show hindered magnetocaloric potential compared to Mn<sub>1-x</sub>Fe<sub>x</sub>NiSi<sub>0.95</sub>Al<sub>0.05</sub> compounds.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"39 ","pages":"Article 102321"},"PeriodicalIF":2.9000,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Materialia","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2589152924003181","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2024/12/15 0:00:00","PubModel":"Epub","JCR":"Q2","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
MM'X compounds such as MnNiSi0.95Al0.05 are potential candidates for room temperature magnetocaloric cooling prototypes due to a magnetostructural transition occurring between TiNiSi orthorhombic and Ni2In hexagonal structure-types. Here, Fe substituted MnNiSi0.95Al0.05 is synthesized by arc melting and subsequent heat treatment. Mn1-xFexNiSi0.95Al0.05 and Mn1-yNi1-yFe2ySi0.95Al0.05 substitutions feature both the TiNiSi and Ni2In structure-types, and undergo martensitic transitions around room temperature, while MnNi1-zFezSi0.95Al0.05 compositions display MgZn2 and Mn5Si3 hexagonal structure-types. The stronger covalent character induced by Fe substitution impacts the structural transitions, shifting them to room temperature for Mn0.5Fe0.5NiSi0.95Al0.05 and Mn0.68Ni0.68Fe0.64Si0.95Al0.05, which undergo transitions during heating at 305 and 302 K, respectively. The orthorhombic structures display anisotropic thermal expansion, and we observe a negative thermal expansion for Mn0.45Fe0.55NiSi0.95Al0.05 and a null expansion for Mn0.68Ni0.68Fe0.64Si0.95Al0.05. Finally, density functional theory calculations predict a larger magnetic moment in Mn0.68Ni0.68Fe0.64Si0.95Al0.05, which is confirmed both from neutron diffraction and macroscopic measurements. However, due to inhomogeneity attributed to the heat treatment condition, Mn1-yNi1-yFe2ySi0.95Al0.05 compounds show hindered magnetocaloric potential compared to Mn1-xFexNiSi0.95Al0.05 compounds.
期刊介绍：
Materialia is a multidisciplinary journal of materials science and engineering that publishes original peer-reviewed research articles. Articles in Materialia advance the understanding of the relationship between processing, structure, property, and function of materials.
Materialia publishes full-length research articles, review articles, and letters (short communications). In addition to receiving direct submissions, Materialia also accepts transfers from Acta Materialia, Inc. partner journals. Materialia offers authors the choice to publish on an open access model (with author fee), or on a subscription model (with no author fee).
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