Synchrotron X-ray characterization of materials synthesized under microwave irradiation

Nakamura, Nathan; Reeja‐Jayan, B.

doi:10.1557/jmr.2018.465

Cited by 9 publications

(8 citation statements)

References 53 publications

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“…To confirm the selective heating of a single Cs cation in the FAU zeolite cavity, in situ x-ray measurements under MW were performed at the SPring-8 synchrotron facility (Hyogo, Japan). While several in situ x-ray analytical methods under MW have been reported ( 42 ), we focused on HEXTS measurement coupled with pair distribution function (PDF) analysis ( 43 ) and x-ray absorption spectroscopy (XAS) measurements. A pelletized Cs + -FAU disk with a thickness of 0.75 mm fixed in the quartz tube was used as the specimen for the synchrotron measurements (fig.…”

Section: Resultsmentioning

confidence: 99%

Direct microwave energy input on a single cation for outstanding selective catalysis

Kishimoto,

Yoshioka,

Ishibashi

et al. 2023

Sci. Adv.

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Microwave (MW)–driven catalytic systems are attracting attention not only as an aggressive electrification strategy of the chemical industry but also as creating a unique catalytic reaction field that conventional equilibrium heating cannot achieve. This study unlocked direct and selective heating of single alkali metal cations in the pores of aluminosilicate zeolites under MW. Selectively heated Cs + cations in FAU zeolite exhibited selective CH 4 combustion performance, that is, CO x generation at the heated Cs + cations selectively occurred while side reactions in the low-temperature gas phase were suppressed. The Cs-O pair distribution function revealed by synchrotron-based in situ x-ray total scattering gave us direct evidence of peculiar displacement induced by MW, which was consistent with the results of molecular dynamics simulation mimicking MW heating. The concept of selective monoatomic heating by MW is expected to open a next stage in “microwave catalysis” science by providing physicochemical insights into “microwave effects.”

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Section: Resultsmentioning

confidence: 99%

Direct microwave energy input on a single cation for outstanding selective catalysis

Kishimoto,

Yoshioka,

Ishibashi

et al. 2023

Sci. Adv.

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“…The heat transfer of WB heating starts from the surface of the material; the rate of heat flow to the bulk of the material is dependent on several factors such as specific heat, thermal conductivity, and viscosity. Furthermore, the heat distribution from the WB is not homogenous, where more significant heat is distributed on the surface of the material and lower heat is distributed into the bulk of the material [34][35][36]. The non-uniform heat distribution by the WB heating method results in the requirement of a longer heating time to initiate the crosslinking reaction in the formation of a hydrogel.…”

Section: Formation Mechanism Of the Wbh And Mwh Hydrogelsmentioning

confidence: 99%

“…Ohmic heating occurs from the oscillation of the free ions (e.g., Na + from NaOH and Clfrom ECH); the oscillation triggers collision with neighboring molecules and creates heat energy. Dielectric heating occurs due to the rotation of molecular dipoles as the molecules attempt to align to the oscillating MW field; the alignment causes friction, creating heat energy [34][35][36]. The MW irradiation allows faster heating and uniform heat distribution on the surface and within the bulk of materials.…”

Section: Formation Mechanism Of the Wbh And Mwh Hydrogelsmentioning

confidence: 99%

Investigation of the influence of crosslinking activation methods on the physicochemical and Cu(II) adsorption characteristics of cellulose hydrogels

Santoso

Angkawijaya

Bundjaja

et al. 2022

Journal of Environmental Chemical Engineering

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“…All field-assisted processes (including synthesis and sintering) are inherently time dependent, which makes it challenging to understand underlying dynamic effects without some form of in situ monitoring while the field is being applied. [95][96][97][98] Such in situ experiments become extremely important to conduct local structural characterization that can provide evidence for the formation and impacts of multiscale defects (from atomic to microscale) during these processes. 99,100 Many challenges remain with regards to developing instrumentation for in situ data collection that is also compatible with field exposure.…”

Section: In Situ Characterizationmentioning

confidence: 99%

Far-from-equilibrium effects of electric and electromagnetic fields in ceramics synthesis and processing

Reeja‐Jayan

Luo

2021

MRS Bulletin

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Electric and electromagnetic fields can promote far-from-equilibrium chemical reactions, phase transformations, and microstructural evolution. On the one hand, both direct electric fields and time-varying electromagnetic fields can change the atomic and microscale structure of materials in ways that differ from conventional methods. On the other hand, ultrafast densification in a matter of seconds (e.g., in flash sintering) and electrically induced microstructural evolution open up new opportunities for materials processing. In many cases, the external fields absorbed within a material may result in "nonthermal" effects. In other cases, thermal effects dominate, but applied fields can still influence the microstructural evolution or generate nonequilibrium defects. Consequently, new behavior evolves such as ceramics that become ductile due to high densities of dislocations created by the far-from-equilibrium processing. Many open scientific questions remain about the fundamental mechanisms underlying such interactions of external fields with matter. From an industrial standpoint, processing advanced materials using externally applied fields can have a smaller energy footprint compared to conventional methods and as such will have a profound impact on society.

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Synchrotron X-ray characterization of materials synthesized under microwave irradiation

Abstract: Abstract

Cited by 9 publications

References 53 publications

Direct microwave energy input on a single cation for outstanding selective catalysis

Direct microwave energy input on a single cation for outstanding selective catalysis

Investigation of the influence of crosslinking activation methods on the physicochemical and Cu(II) adsorption characteristics of cellulose hydrogels

Far-from-equilibrium effects of electric and electromagnetic fields in ceramics synthesis and processing

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