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62. THE MAGNETIC ANISOTROPY OF R2Fe14B COMPOUNDS.

Author

Franse, J. J. M., Verhoef, R., and Radwanski, R. J.

Subjects
MAGNETIC anisotropy, MAGNETIZATION, IRON compounds, SINGLE crystals, MAGNETIC fields, COUPLING reactions (Chemistry)
Published
1991

74. Magnetic properties of Er2Fe14−xMnxC

Author

Verhoef, R., de Boer, F.R., Franse, J.J.M., Denissen, C.J.M., Jacobs, T.H., and Buschow, K.H.J.

Abstract

The magnetic properties of the compounds Er2Fe14−xMnxhave been determined by means of X-ray diffraction, magnetic measurement and 57Fe Mössbauer spectroscopy. Magnetization measurements made in fields up to 38 T showed that the saturation moment exhibits a minimum at a Mn concentration corresponding to about x=2, due to the antiparallel coupling between the R and 3d sublattice magnetizations the latter becoming strongly reduced with increasing Mn concentration. The reduction of the 3d-sublattice magnetization is accompnied by a corresponding reduction in the 57FE hyperfine fields and by a lowering of the Curie temperature and the spin orientation temperature. Most of the compounds investigated have a break in the magnetization curves measured at 4.2 K which is interpreted as the onset of decoupling between the antiparallel rare earth and 3d sublattices. A mean field analysis was used to derive the intersublattice molecular field coefficient nRT.

Published
1989
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75. Magnetic anisotropy in Pr2Fe14−xMnxC compounds

Author

Verhoef, R., de Boer, F.R., Fu-ming, Yang, Zhi-dong, Zhang, de Mooij, B.D., and Buschow, K.H.J.

Abstract

The concentration dependence of the magnetic properties of Pr2Fe14−xMnxC, 0.3≤x≤10, compounds has been in Mn substitution leads to a decrease of the saturation moment, accompanied by a strong reduction of the Curie temperature. Anisotropy constants have been deduced from an analysis of high-field magnetisation isotherms at 4.2 K. First-order magnetisation processes (FOMP) have been observed.

Published
1989
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76. Magnetization reversal in microscopic NdFeB single crystals

Author

Richter, H.J., Hempel, K.A., and Verhoef, R.

Abstract

Using a very high sensitive magnetometer the magnetization reversal of very small isolated NdFeB single crystals (μm range and below) is investigated. It turns out that similarities in the hysteresis cycle between barium ferrite single crystals and the Nd compounds can be observed. Sample size and morphology are controlled using an electron scanning microscope. While in ferrite samples of the range 1 μm single domain behaviour can be observed, the Nd2Fe14B samples still show evidence of domain wall motions.

Published
1989
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84. MAGNETIC PROPERTIES OF Pr2Fe14-xMnxC

Author

Buschow, K. H. J., primary, Denissen, C. J. M., additional, de Mooij, B. D., additional, de Boer, F. R., additional, Verhoef, R., additional, and Zhi-dong, Zhang, additional

Published
1988
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90. Population Registers and Population Statistics

Author

Van De Kaa Dj and Verhoef R

Subjects
Government, education.field_of_study, Data collection, Actuarial science, Population statistics, Population, General Medicine, Census, Political science, Population growth, Confidentiality, education, Demographic statistics, Demography
Abstract

The authors examine the use of population registers in the production of demographic statistics. "To do this we first describe these registers; we then examine their further development as an independent source of population statistics--including current population estimates vital and migration statistics--and as an alternative to population censuses. In conclusion we consider a number of essential features of registers including the original collection of data the systems lifetime privacy protection and the governments ability to bring about a balance among conflicting interests regarding the collection and use of the data." The discussion is illustrated using examples from the Netherlands and Denmark. (EXCERPT)

Published
1987

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