第140回先端計測オープンセミナー

2019年3月18日 (月) 13:00-15:00

国立研究開発法人 物質・材料研究機構
千現地区 管理棟1階 第2会議室

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(1) Dr. David N. Müller, Staff scientist, Peter Grünberg Institute (PGI6), Research Center Juelich, Germany.
(2) Dr. Thomas Duchon, Postdoctoral Researcher, Peter Grünberg Institute (PGI-6), Research Center Juelich, Germany.

(1) Probing the Solid/Gas Interface of Solid State Electrochemical Devices with X-Ray Spectroscopic Methods
(2) Towards Universal Liquid in-situ Electrochemistry in Photoemission Microscopy

(1) The fascinating and useful properties of complex oxides are in many instances connected to their interaction with liquids or gases at the phase boundary, the latter especially at elevated temperatures. Though strides have been made in the development of “ambient pressure” variants of X-Ray photoemission and absorption spectroscopy it may be still a long way to go to close the gap between model and real systems: The reason for this lies in the dynamics of the materials surface, which may undergo segregation/precipitation reactions essentially changing the chemistry and thus physical behavior from the one of the parent material. In this talk, I will use two widely studied perovskite material systems - donor doped SrTiO₃ and the (La,Sr)(Fe,Co,Ti)O_3-δ family - to showcase how spectroscopic operando observation of surface dynamics can give valuable insights how these materials behave under thermodynamic stimuli on an atomistic scale.

(2) The use of photoemission electron microscopy (PEEM) as a probe of liquid electrolytes has been an elusive goal, motivated by the breadth of information the technique can provide, but hindered by many technical difficulties. The traditional concept of differential pumping is challenging to implement in PEEM due to the presence of a high potential difference between a specimen and extractor lens. One of the ways to overcome the problem is to use electron transparent membranes to seal the liquid sample, thus retaining high vacuum conditions between the lens and sample. Here, we present the current approaches that allow for investigation of interfacial liquid electrochemistry via either soft or hard X-ray PEEM, offering a rare combination of morphological, chemical and structural information with real-time imaging of electrodes and products of electrolysis, electrodeposition, and other electrically induced processes.