The thermal expansion of (Fe1−yNiy)Si
We have measured the thermal expansion of (Fe1−yNiy)Si for y = 0, 0.1 and 0.2, between 40 and 1273 K. Above ~700 K the unit-cell volumes of the samples decrease approximately linearly with increasing Ni content. Below ~200 K the unit-cell volume of FeSi falls to a value between that of (Fe0.9Ni0.1...
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Published in | Journal of physics. Condensed matter Vol. 29; no. 33; p. 335701 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
England
IOP Publishing
23.08.2017
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Subjects | |
Online Access | Get full text |
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Summary: | We have measured the thermal expansion of (Fe1−yNiy)Si for y = 0, 0.1 and 0.2, between 40 and 1273 K. Above ~700 K the unit-cell volumes of the samples decrease approximately linearly with increasing Ni content. Below ~200 K the unit-cell volume of FeSi falls to a value between that of (Fe0.9Ni0.1)Si and (Fe0.8Ni0.2)Si. We attribute this extra contraction of the FeSi, which is a narrow band-gap semiconductor, to the depopulation of the conduction band at low temperatures; in the two alloys the additional electrons introduced by the substitution of Ni lead to the conduction band always being populated. We have fit the unit-cell volume data with a Debye internal energy model of thermal expansion and an additional volume term, above 800 K, to take account of the volumetric changes associated with changes in the composition of the sample. Using the thermophysical parameters of the fit we have estimated the band gap in FeSi to be 21(1) meV and the unit-cell volume change in FeSi associated with the depopulation of the conduction band to be 0.066(35) Å3/unit-cell. |
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Bibliography: | JPCM-109118 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0953-8984 1361-648X |
DOI: | 10.1088/1361-648X/aa797d |