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Article Dans Une Revue Acta Materialia Année : 2012

The influence of buffer/capping-layer-mediated stress on the coercivity of NdFeB films

Dominique Givord
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Nora Dempsey

Résumé

The influence of buffer/capping-layer-mediated stress on the coercivity of NdFeB films is demonstrated. NdFeB films, 5 μm thick and rich in Nd, were deposited on Si/SiO2 and Al2O3 substrates, with or without buffer/capping layers of Ta. The coercivity of Ta-free samples (∼0.5 T) is significantly less than that achieved in samples with Ta present as a buffer and/or capping layer (1.7-1.8 T). The as-sputtered Ta layers are under strong compressive stress due to peening. During post-deposition annealing to crystallize the Nd2Fe14B phase, stresses are relieved in the Ta layer. This leads in turn to a compressive stress in the NdFeB layer, inducing extrusion of a Nd-rich phase up through the NdFeB layer. The high values of coercivity achieved in Ta-containing structures are attributed to good coverage of individual Nd2Fe14B grains with the redistributed Nd-rich phase.

Dates et versions

hal-00969044 , version 1 (02-04-2014)

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Citer

Yuepeng Zhang, Dominique Givord, Nora Dempsey. The influence of buffer/capping-layer-mediated stress on the coercivity of NdFeB films. Acta Materialia, 2012, 60, pp.3783-3788. ⟨10.1016/j.actamat.2012.03.051⟩. ⟨hal-00969044⟩

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