Development of an integrated high-voltage electron microscope-gas chromatograph-quadrupole mass spectrometer system for the operando analysis of catalytic gas reactions.

This paper describes the development of a gas chromatography-quadrupole mass spectrometry system attached to a differential-pumping-type environmental cell of the reaction science high-voltage electron microscopy instrument at Nagoya University to distinguish unambiguously between different gas species with the same mass-to-charge ratio. Several model experiments were used to verify the efficacy of the newly proposed system, confirming its ability to analye the atomic-level structural changes during heterogeneous catalysts and the associated gas-reaction kinetics simultaneously, providing new insights into operando measurements in the field of environmental transmission electron microscopy.

Femtosecond X-ray Laser Reveals Intact Sea-Island Structures of Metastable Solid-State Electrolytes for Batteries.

Experimental characterization of the nanostructure of metastable functional materials has attracted significant attention with recent advances in computational materials discovery. However, since metastable glass-ceramics are easily damaged by irradiation, damage-free nanoimaging has not been realized thus far. Herein, we propose novel high-contrast coherent diffractive imaging that quantitatively analyzes the intact internal nanostructure of metastable glass-ceramics using femtosecond X-ray pulses. The immersion of sample particles in a solvent helps enhance the reconstructed image contrast and allows us to distinguish an ∼7% electron density difference between an amorphous form and crystals. Furthermore, morphological operations with a band-pass filter quantitatively elucidate the depth information. The evaluated volume ratio of the amorphous to crystalline phases is ∼2.5:1 for the measured metastable (Li2S)70-(P2S5)30 glass-ceramic particle. Sulfide glass-ceramics are used as electrolytes for all-solid-state batteries, which are indispensable for reducing the carbon footprint. Our results will facilitate structural studies on fragile metastable materials with important scientific and industrial implications.

Environmental high-voltage S/TEM combined with a quadrupole mass spectrometer for concurrent in situ structural characterization and detection of product gas molecules associated with chemical reactions.

We introduce herein a combined environmental high-voltage electron microscope and a quadrupole mass spectrometer to detect product gas species associated with chemical reactions occurring in the microscope, which allows new operando experiments of, for instance, observing catalytic reactions by concurrent high-resolution transmission electron microscope (TEM) observation. We demonstrate the preliminary results of redox reactions, where the product gas species are unambiguously detected, associated with the expected structural transformations observed with TEM.

Development of an analytical environmental TEM system and its application.

Many automotive materials, such as catalysts and fuel cell materials, undergo significant changes in structure or properties when subjected to temperature change or the addition of a gas. For this reason, in the development of these materials, it is important to study the behavior of the material under controlled temperatures and gaseous atmospheres. Recently, a new environmental transmission electron microscope (TEM) has been developed for observation with a high resolution at high temperatures and under gaseous atmospheres, thus making it possible to analyze reaction processes in details. Also, the new TEM provides a high degree of reproducibility of observation conditions, thus making it possible to compare and validate observation of various specimens under a given set of conditions. Furthermore, easiness of gas condition and temperature control can provide a powerful tool for the studying of the mechanism of material change, such as oxidation and reduction reactions.

Development of a real-time stereo transmission electron microscope.

A new transmission electron microscope that allows for stereoscopic observations in real time at a video rate has been developed. In order to make stereo pairs at a high speed, illumination of a specimen from two directions instead of specimen tilting is adopted. Two electrostatic deflectors make it possible to alternate the illumination direction within a blank period of 1.2 ms between two adjacent video fields. Three dimensional displays give observers a stereo impression without the need for special glasses. By considering the circle of least confusion due to spherical aberration, a lateral resolution <1 nm and a longitudinal resolution of 6.3 nm are possible with a proper defocused condition. This improvement of the resolution is confirmed for the image of Au fine particles. The motion of objects in the lateral direction can be detected up to a speed of 8.3 nm s(-1). Using this microscope fine particles of ZnO were observed.