Magnetic volume effects

A variety of experimental techniques have been employed to research the material of this chapter, many of which we shall not even mention. For example, pressure as well as temperature has been used as an experimental variable to study volume effects. Dielectric constants, indices of refraction, and nuclear magnetic resonsance (NMR) spectra are used, as well as mechanical relaxations, to monitor the onset of the glassy state. X-ray, electron, and neutron diffraction are used to elucidate structure along with electron microscopy. It would take us too far afield to trace all these different techniques and the results obtained from each, so we restrict ourselves to discussing only a few types of experimental data. Our failure to mention all sources of data does not imply that these other techniques have not been employed to good advantage in the study of the topics contained herein. 

Lelievre-Bema, E., Rouchy, J. and Ballou, R. (1994) Field induced first order magnetic transition and associated volume effect in TbMn2, J. Mag. Mag. Mar., 137, L6-L10. 

Furthermore, the insertion of hydrogen atoms doesn t practically change the intersublattice exchange interactions in R2Fei4B compounds. To explain this result a number of factors should be taken into account (i) the volume effect under the hydrogen atoms incorporation, which increases the Fe-Fe and R-Fe interatomic distances, (ii) the enhancement of magnetism of the iron sublattice, (iii) the elastic... 

Typical results from an analytically based design procedure published by Howe et al. (1987) are shown in fig. 55. They relate to a motor equipped with pole-face mounted magnets, and have a specified short-time overload capacity. Howe et al. discussed the effect on magnet volume of a variable electric loading Q and variable rotor diameter D, the magnet being dimensional to withstand the overload. They show that increases in either D or Q result in a reduction in magnet volume. 

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