Browsing by Author "Faehler, Sebastian"

Fe-Pt films with an Fe/Pt ratio close to one call be electrodeposited from an FeSO(4)-H(2)PtCl(6)-Na(2)SO(4) electrolyte. At the deposition potential, the hydrogen evolution and the reduction of the Pt complex are diffusion limited. and Fe overpotential deposition has not yet set in. The sources of the Fe incorporation are iron hydroxide formation together with Fe underpotential deposition due to Fe-Pt alloy formation. Mossbauer measurements show that the iron in the iron hydroxide is predominantly Fe(III). For stoichiometry reasons, a Pt-rich Fe-Pt phase must be present ill addition to the Fe(III)-hydroxide. The Fe(3+), that takes part in the hydroxide formation is produced in the electrolyte by the oxidation of Fe(2+) by the complexed Pt ion. This exchange reaction results in a significantly higher Fe(3+), content in the FeSO(4)-H(2)PtCl(6)-Na(2)SO(4) electrolyte ill comparison to the same electrolyte without H(2)PtCl(6). Fe(III)-hydroxide formation call be depressed by adding citric acid, that acts as buffering and complexing agent. This leads to a lower iron content of the deposits. The Fe/Pt ratio close to one that is needed for hard magnetic properties call, however, only be achieved with a significant incorporation of it-on hydroxide. (c) 2008 Elsevier Ltd. All rights reserved.

Pulsed laser deposition (PLD) was used to deposit FePt films onto single crystalline MgO substrates. When deposited at room temperature, films grow epitaxial within the A1 phase. Structure and magnetic properties were examined by X-ray diffraction, Rutherford Backscattering Spectrometry (RBS), magneto-optic Kerr effect, Mossbauer spectroscopy, and Magnetic Orientation Mossbauer Spectroscopy (MOMS). These measurements allow to exclude local ordering and reveal the anisotropic intrinsic and extrinsic magnetic properties. These results are discussed with respect to the texture and microstructure of these films. (c) 2007 Elsevier B.V. All rights reserved.

A new ferromagnetic shape memory thin film system. Fe-Pd-Cu, was developed using ab initio calculations, combinatorial fabrication and high-throughput experimentation methods. Reversible martensitic transformations are found in extended compositional regions, which have increased fcc-fct transformation temperatures in comparison to previously published results. High resolution transmission electron microscopy verified the existence of a homogeneous ternary phase without precipitates. Curie temperature, saturation polarization and orbital magnetism are only moderately decreased by alloying with nonmagnetic Cu Compared to the binary system; enhanced Invar-type thermal expansion anomalies in terms of an increased volume magnetostriction are predicted. Complementary experiments on splat-fabricated bulk Fe-Pd-Cu samples showed an enhanced stability of the disordered transforming Fe(70)Pd(30) phase against decomposition. From the comparison of bulk and thin film results, it can be Inferred that, for ternary systems, the Fe content, rather than the valence electron concentration, should be regarded as the decisive factor determining the fcc-fct transformation temperature (C) 2010 Acta Materialia Inc Published by Elsevier Ltd. All rights reserved