Solid–Liquid Interface Structure of Muscovite Mica in SrCl 2

International audienceThe structure of the solid-liquid interface formed by muscovite mica in contact with two divalent ionic solutions (SrCl2 and BaCl2) is determined using in situ surface X-ray diffraction using both specular and non-specular crystal truncation rods. The 0.5 monolayer of monovalent potassium present at the surface after cleavage is replaced by approximately 0.25 monolayer of divalent ions, closely corresponding to ideal charge compensation within the Stern layer in both cases. The adsorption site of the divalent ions is determined to be in the surface ditrigonal cavities with minor out-of-plane relaxations that are consistent with their ionic radii. The divalent ions are adsorbed in a partly hydrated state (partial solvation sphere). The liquid ordering induced by the presence of the highly ordered crystalline mica is limited to the first 8-10 angstrom from the topmost crystalline surface layer. These results partly agree with previous studies in terms of interface composition, but there are significant differences regarding the structural details of these interfaces

Solid–Liquid Interface Structure of Muscovite Mica in CsCl and RbBr Solutions

The solid−liquid interface formed by single terminated muscovite mica in contact with two different ionic solutions is analyzed using surface X-ray diffraction. Specular and nonspecular crystal truncation rods of freshly cleaved mica immersed in CsCl or RbBr aqueous solution were measured. The half monolayer of the surface potassium ions present after the cleavage is completely replaced by the positive ions (Cs$^{+}$ or Rb$^{+}$) from the solution. These ions are located in the ditrigonal surface cavities with small outward relaxations with respect to the bulk potassium position. Wefind evidence for the presence of a partly ordered hydration shell around the surface Cs$^+$ or Rbs$^+$ ions and partly ordered negative ions in the solution. The lateral liquidordering induced by the crystalline surface vanishes at distances larger than 5 Å from the surface

DESA1002 'Nine Quarter City' - <Yon Syafni Samat>

This semester, my studio group is allocated Bern for the Nine Quarter City project. This city comprises of 16 adjacent blocks. A figure-ground plan has been created and serves as the basis for the initial tasks that will be undertaken as a ‘conversation’ with the other members of the group. We are charged with elaborating on the basic plan, deciding on a range of buildings that the quarter of the city needs, then deciding on a specific program for the allocated city block and developing a concrete architectural proposal for one building on the specified block. This semester, I am designing a hotel in Bern. My decision of designing a hotel is influenced by the neighbouring buildings. There is a train station, a clock tower, an information centre and a commercial headquarters for Toblerone and Swatch in the vicinity of the area. As these buildings are usually visited and often being utilized by the visitors of the city, I really think that there is a need for a hotel in that area in order to cater for a pleasant sojourn in Bern. My design emphasizes strongly on the façade of the building as this is the main attraction of the hotel. I also placed a strong attention on the details of each level and rooms of the hotel because I want to make a strong impression for the guests about the hotel. I want them to be captured by the architecture of the building, and will never forget about it

Metal ion-exchange on the muscovite mica surface

The surface potassium ions of muscovite mica were exchanged for several different metal ions from aqueous solution (Ag, Ca, V, Mn, Fe, Ni, Cu, Zn, Co, and Cd). The surfaces were rinsed in water, dried under nitrogen atmosphere, and subsequently analysed using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and, for half the systems, surface X-ray diffraction (SXRD). XPS and SXRD confirmed the presence of the different metal ions at the muscovite mica surface, with a partial monolayer of the monovalent and divalent ions present on the surface. No counter ions from the used salts were detected. AFM revealed that Ni-, and Fe-terminated muscovite mica surfaces were partially covered by nanoparticles, most likely consisting of metal (hydr)oxide. The exchanged ions remained on the surface after rinsing with ultra pure water three times. SXRD showed that Cd and Ag have a lower affinity for the muscovite mica surface than Cu, Ca, and Mn

Dibenzo Crown Ether Layer Formation on Muscovite Mica

Stable layers of crown ethers were grown on muscovite mica using the potassium–crown ether interaction. The multilayers were grown from solution and from the vapor phase and were analyzed with atomic force microscopy (AFM), matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, and surface X-ray diffraction (SXRD). The results show that the first molecular layer of the three investigated dibenzo crown ethers is more rigid than the second because of the strong interaction of the first molecular layer with the potassium ions on the surface of muscovite mica. SXRD measurements revealed that for all of the investigated dibenzo crown ethers the first molecule lies relatively flat whereas the second lies more upright. The SXRD measurements further revealed that the molecules of the first layer of dibenzo-15-crown-5 are on top of a potassium atom, showing that the binding mechanism of this layer is indeed of the coordination complex form. The AFM and SXRD data are in good agreement, and the combination of these techniques is therefore a powerful way to determine the molecular orientation at surfaces

Muscovite mica: Flatter than a pancake

Item does not contain fulltex