Anomalous thermal expansion in Nd2Fe17-δGaδ (δ=0 - 2)
- 1. Materials Sciences Division, Lawrence Berkeley National Laboratory, and Department of Materials Science and Mineral Engineering, University of California, Berkeley, California 94720-1760 (United States)
- 2. Department of Physics, Centre for the Physics of Materials, McGill University, 3600 University Street, Montreal, Quebec H3A 2T8 (Canada)
- 3. Neutron and Condensed Matter Science, AECL, Chalk River, Ontario K0J 1P0 (Canada)
- 4. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
- 5. Department of Materials Science and Mineral Engineering, University of California, Berkeley, California 94720-1760 (United States)
Description
In Nd2Fe17-δGaδ (δ=0;0.5;1;1.5;2), Ga substitutes for Fe without changing the crystal structure. Neutron diffraction measurements show that Ga preferentially substitutes for Fe in the 18h sites only. The magnetic moments in Nd2Fe17-δGaδ, below the Curie temperature, Tc, are found to be in the basal plane. Below Tc the unit cell constant, c, decreases with increasing temperature for Nd2Fe17-δGaδ (δ≤1). For Nd2Fe17-δGaδ (δ>1), the thermal expansion coefficient changes sign and becomes positive for Nd2Fe15Ga2. The relative decrease in the Fe(6c)- Fe(6c) distance is twice as large as the decrease in the c axis below Tc. Below Tc, the Fe(6c)- Fe(6c) distance decreases with an increase in the Ga concentration, while above Tc the Fe(6c)- Fe(6c) distances are found to be independent on Ga concentration indicating that the presence of Ga decreases the negative exchange coupling between Fe atoms. copyright 1999 American Institute of Physics
Additional details
Publishing Information
- Journal Title
- Journal of Applied Physics
- Journal Volume
- 85
- Journal Issue
- 8
- Journal Page Range
- p. 4669-4671
- ISSN
- 0021-8979
- CODEN
- JAPIAU
INIS
- Country of Publication
- United States
- Country of Input or Organization
- United States
- INIS RN
- 30037729
- Subject category
- S36: MATERIALS SCIENCE;
- Descriptors DEI
- CRYSTAL STRUCTURE; FERROMAGNETIC MATERIALS; GALLIUM ALLOYS; IRON ALLOYS; MAGNETIC MOMENTS; NEODYMIUM ALLOYS; NEUTRON DIFFRACTION; TEMPERATURE DEPENDENCE; THERMAL EXPANSION
- Descriptors DEC
- ALLOYS; COHERENT SCATTERING; DIFFRACTION; EXPANSION; MAGNETIC MATERIALS; MATERIALS; RARE EARTH ALLOYS; SCATTERING; TRANSITION ELEMENT ALLOYS