A small angle neutron scattering and electrochemical impedance spectroscopy study of the nanostructure of the iron chalcogenide glass ion-selective electrode

In situ synchrotron radiation grazing incidence X-ray diffraction—A powerful technique for the characterization of solid-state ion-selective electrode surfaces

“…3, can be derived by reconciling the present SR-GIXRD outcomes with the aforesaid information on the nanostructural network of the iron chalcogenide glass ISE [37]. Initially, the iron doped nanocrystalline inclusions of GeSe and Sb 2 Se 3 (shown as white oval-like rods in Fig.…”

“…3a), which are more ordered and less noble relative to the surrounding glassy matrix owing to their much lower third law entropies, are preferentially attacked oxidatively, and become depleted from the MSL of the iron chalcogenide ISE with time. Ultimately, the MSL of the sensor becomes so depleted with respect to the nanocrystalline phases of GeSe and Sb 2 Se 3 , which have been shown previously [37] to be very important to the electrical conductivity of the sensor, that it is passivated and the sensor looses its response attributes. Furthermore, the formation of FeO on continuous exposure to saline solution -the long-term product of the oxidative attack of the GeSe and Sb 2 Se 3 phases in alkaline solution -is depositing in all likelihood at the sites that have been depleted with respect to GeSe and Sb 2 Se 3 (depicted as grey oval-like rods in Fig.…”

“…In a previous small angle neutron scattering (SANS) study of the bulk iron nanostructure of the glassy matrix of the iron chalcogenide glass ISE [37], it was shown that there is a strong correlation between the electrical conductivity and concomitant electrochemical reactivity of the Fe III ISE and its highly ordered, interwoven and interconnected nano-network of conductive iron nanostructural features (viz., filaments of highly doped semiconducting iron chalcogenide nanocrystallites (probably GeSe and Sb 2 Se 3 -as seen in the present SR-GIXRD study -laden with the iron dopant), as evidenced by scanning electron microscopy (SEM) [29,30]; refer to Fig. 2 for an SEM microstructure of this polished membrane).…”

Response Mechanisms and New Approaches with Solid‐State Ion‐Selective Electrodes: A Powerful Multitechnique Materials Characterization Approach

“…A reaction model, which is depicted by the cartoon in Figure 2, can be derived by reconciling the previously published data on the reactivity [33], response attributes [8,10,45] as well as SANS, SEM and AFM nanostructural information on the MSL [22,43,44] of the iron chalcogenide glass ISE. Initially, the iron doped nanocrystalline inclusions of GeSe and Sb 2 Se 3 (shown as white oval-like rods in Fig.…”

“…Previous SANS data for the iron chalcogenide glass ISE [43] also showed a significant boost in the neutron scattering of nanoparticles at iron dopant levels above 2 at%, and the volume percentage of neutron scatterers was quite small (i.e., a few percent). Clearly, this points to an elaborate nanostructural network of conductive filaments -highly conductive iron doped GeSe and Sb 2 Se 3 -that are able to impart a large effect on the bulk electrical conductivity of the membrane.…”