The aim of this thesis is the investigation of the different contributions to the thermal expansion of intermetallic rare earth compounds, where the magnetic influences are of main interest. The measurements were performed on a X-ray powder diffractometer. At first there is an overview over the theory for understanding the thermal expansion of intermetallic magnetic compounds. Simple models for the contributions of the phonons, the band-electrons, the itinerant magnetism and the local rare-earth magnetism are presented. Then the contributions of the phonons, the band electrons and the spin fluctuations are separated by a comparison of the thermal expansion of the isostructural cubic Laves phases YAl_2, YNi_2, YCo_2 and Y_0_._9Lu_0_._1Mn_2. In the magnetic RCo_2 compounds (R=rare earth) there are in addition two interesting effects below the magnetic ordering temperature: The Co- magnetism causes a large positive contribution to the volume of the unit cell and the crystal field interaction of the localized R-atoms is responsible for a distortion of the cubic symmetry along the direction of magnetization. A detailed investigation of the contributions of the crystal field- and the exchange- interaction of the R-atoms to the thermal expansion of the orthorhombic RCu_2 is presented on the samples TmCu_2 and GdCu_2. Further the influences of both itinerant and local magnetism are also studied on the YMn_2H_x hydrides and on the hexagonal YCo_4B and CeCo_4B.
en
dc.language
Deutsch
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dc.language.iso
de
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dc.rights.uri
http://rightsstatements.org/vocab/InC/1.0/
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dc.subject
Seltenerdmetall
de
dc.subject
Intermetallische Verbindungen
de
dc.subject
Wärmeausdehnung
de
dc.subject
Magnetostriktion
de
dc.title
Thermische Ausdehnung und spontane Magnetostriktion in intermetallischen Selten-Erd-Verbindungen
