Date/Time: 04-23-2019 - Tuesday - 05:00 PM - 07:00 PM
Julio Rodriguez Manzo1 Khim Karki1 Daan Hein Alsem1 Norman Salmon1

1, Hummingbird Scientific, Lacey, Washington, United States

Transmission electron microscopy (TEM) sample holders with biasing capabilities in which a mechanical mobile probe acts like one of the electrodes allow to investigate, simultaneously, the electrical properties of materials and their structural and chemical states, by using the full battery of characterization techniques available in a TEM (high-resolution imaging, electron-based spectroscopy, electron diffraction, etc.). This in-situ biasing microscopy technique has been used to investigate the conductance through rows of metal and carbon atoms [1,2], the switching of resistive memories [3], anode materials for batteries [4,5], etc. Here, we present several examples in where a recently developed in-situ TEM sample holder with a mobile probe was used to bias samples locally and discuss the practical considerations of the technique, with the objective of facilitating the experiments—which can be challenging during the mobile probe mechanical approach to the sample.

Specifically, we discuss how to approach the sample with coarse and piezoelectrically-driven fine movements and how to prepare the mobile probe, inside the TEM column, to obtain a good electrical contact between the sample and the probe prior to the experiment; by “good” we understand contacts without contamination or oxide layers that can disrupt the contact’s intrinsic electrical properties. The sample holder used during these experiments allows to approach the sample with the mobile probe in manual coarse mode with smooth and uncoupled steps of μm (or fractions of μm) among the three spatial axes. Likewise, it allows to do the final contact approach with a piezoelectric controlled mechanism that allows uncoupled nanometer-sized (or less) steps among the three spatial axes. We will present three examples: 1) observation of the Li-alloying process in yolk-shell p-Si nanorods@void@nitrogen-doped carbon nanostructures relevant for anode materials in Li-ion batteries [4]; 2) the investigation of the high capacity retention of Sb2Te3/C composites relevant for sodium-ion batteries [5]; and 3) the reaction of a solid-sate electrolyte particles under load. These examples illustrate the convenience of this in-situ biasing technique when creating a contact prior to the experiment is difficult.

[1] Hideaki Ohnishi, Yukihito Kondo, Kunio Takayanagi. Nature 395(1998), p. 780.
[2] Ovidiu Cretu, et al., Nano Letters 13(2013), p. 3487.
[3] David Cooper, et al., Advanced Materials 29(2017), p. 1700212.
[4] Fei-Hu, et al., ACS Nano11(2017), p. 8628.
[5] Ze Yang, et al., Energy Storage Materials 9(2017), p.214

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