Deformation and fracture of crystalline tungsten and fabrication of composite STM probes
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2020Access:
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Ionov A.M., Chekmazov S.V., Usov V., Nesterova M.¿., Aronin A.S., Semenov V.N., Shvets I.V., Bozhko S.I., Deformation and fracture of crystalline tungsten and fabrication of composite STM probes, Ultramicroscopy, 218, 2020Download Item:
Tensile test of W[100] rod constr and creation of comp probe_final ver_for Ultramicroscopy.pdf (Accepted for publication (author's copy) - Peer Reviewed) 858.6Kb
Abstract:
Fracturing microscale constrictions in metallic wires, such as tungsten, platinum, or platinum-iridium, is a common fabrication method used to produce atomically sharp tips for scanning tunneling microscopy (STM), field-emission microscopy and field ion microscopy. Typically, a commercial polycrystalline drawn wire is locally thinned and then fractured by means of a dislocation slip inside the constriction. We examine a special case where a dislocation-free microscale constriction is created and fractured in a single crystal tungsten rod with a long side parallel to the [100] direction. In the absence of dislocations, vacancies become the main defects in the constriction which breaks under the tensile stress of approximately 10 GPa, which is close to the theoretical fracture strength for an ideal monocrystalline tungsten. We propose that the vacancies are removed early in the tensile test by means of deformation annealing, creating a defect-free tungsten constriction which cleaves along the W(100) plane. This approach enables fabrication of new composite STM probes which demonstrate excellent stability, atomic resolution and magnetic contrast that cannot be attained using conventional methods.
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http://people.tcd.ie/caffredahttp://people.tcd.ie/ivchvets
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Author: Caffrey, David; Shvets, Igor
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Ultramicroscopy218
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Full text availableKeywords:
Scanning tunneling microscopy (STM), STM probe preparation, Tension test, Vacancies, Fracture mechanism, Spin-sensitive composite probeDOI:
http://dx.doi.org/10.1016/j.ultramic.2020.113083ISSN:
18792723 03043991Licences: