Atomic sites and stability of Cs+ captured within zeolitic nanocavities

Abstract

Zeolites have potential application as ion-exchangers, catalysts and molecular sieves. Zeolites are once again drawing attention in Japan as stable adsorbents and solidification materials of fission products, such as 137Cs+ from damaged nuclear-power plants. Although there is a long history of scientific studies on the crystal structures and ion-exchange properties of zeolites for practical application, there are still open questions, at the atomic-level, on the physical and chemical origins of selective ion-exchange abilities of different cations and detailed atomic structures of exchanged cations inside the nanoscale cavities of zeolites. Here, the precise locations of Cs+ ions captured within A-type zeolite were analyzed using high-resolution electron microscopy. Together with theoretical calculations, the stable positions of absorbed Cs+ ions in the nanocavities are identified, and the bonding environment within the zeolitic framework is revealed to be a key factor that influences the locations of absorbed cations.

Chirality density wave of the “hidden order” phase in URu 2 Si 2

“…A spatial order alternating the sign of this hexadecapole for neighboring basal planes is the chirality density wave (see Fig. 1D) that consistently explains the HO phenomena as it is observed by Raman and neutron scattering (16)(17)(18)30), magnetic torque (19), X-ray diffraction (20), and other data (11)(12)(13)(14)31).…”

“…The chirality density wave doubles the translational periodicity of the paramagnetic phase, hence it folds the electronic Brillouin zone, as recently observed by angle-resolved photoemission spectroscopy (31). It also gives rise to an energy gap, as previously observed in optics (12)(13)(14) and tunneling experiments (15,32), and shown in figure 4 to originate in expelling the continuum of A 2g excitations.…”

Selective chemical binding enhances cesium tolerance in plants through inhibition of cesium uptake

“…By contrast, it is a general agreement that effects of the chemical treatment are universal across most of the plant species, especially when the chemical works outside of the plants as is the case of CsTolen A. Although various compounds and materials such as zeolites, silicates and crown ethers have been proposed as selective Cs + -capturing agents for the decontamination of radioactive waste water 21 22 23 24 25 26 27 28 , this is the first report, to the best of our knowledge, on a compound which, through selective binding, enables a plant to avoid Cs + uptake and thus harmful accumulation. The efficacy of CsTolen A needs to be assessed in the field at Fukushima, the site of the nuclear accident 29 .…”

Progress in Developing a Structure‐Activity Relationship for the Direct Aromatization of Methane

“…To observe the clustering operando TEM could be performed . However, zeolite samples are very sensitive to electron beam exposure and low dose imaging techniques are necessary, not to damage the zeolite for the duration of an MDA experiment. Further, it remains to be determined if bigger Mo clusters also form inside the pores of the zeolite and whether these carbide clusters can activate methane.…”