Examinando por Autor "Schoenthal, W."

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Acceso Abierto
Single Point Gradiometer for Planetary Applications
(Institute of Electrical and Electronics Engineers, 2015-03-09) Mesa, J. L.; Díaz Michelena, M.; Ciudad, D.; Schoenthal, W.; McHenry, M. E.; Maicas, M.; Aroca, C.; Ministerio de Ciencia e Innovación (MICINN)
We have designed and fabricated a microelectromechanical device, based on the alternating field gradient concept, to measure surface magnetic field gradient on planets. Its sensitivity is 4 10 -4 T/m, which is appropriate for magnetite outcrops and areas with rocks formed at different stages recording geomagnetic field reversals. We present the results obtained with three different prototypes.
Restringido
Synthesis and magnetic properties of single phase titanomagnetites
(AIP Publishing, 2014-03-11) Schoenthal, W.; Liu, X.; Cox, T.; Mesa, J. L.; Maícas, N.; Díaz Michelena, M.; Laughlin, D. E.; McHenry, M. E.
The focus of this paper is the study of cation distributions and resulting magnetizations in titanomagnetites (TMs), (1−x)Fe3O4−xFe2TiO4 solid solutions. TM remnant states are hypothesized to contribute to planetary magnetic field anomalies. This work correlates experimental data with proposed models for the TM pseudobinary. Improved synthesis procedures are reported for single phase Ulvöspinel (Fe2TiO4), and TM solid solutions were made using solid state synthesis techniques. X-ray diffraction and scanning electron microscopy show samples to be single phase solid solutions. M-H curves of TM75, 80, 85, 90, and 95 (TMX where X = at. % of ulvöspinel) were measured using a Physical Property Measurement System at 10 K, in fields of 0 to 8 T. The saturation magnetization was found to be close to that predicted by the Neel model for cation distribution in TMs. M-T curves of the remnant magnetization were measured from 10 K to 350 K. The remnant magnetization was acquired at 10 K by applying an 8 T field and then releasing the field. Experimental Neel temperatures are reported for samples in the Neel model ground state.