Migration Of Copper Ions Research Articles

Introduction of transition metal ions in cationic positions of high-silica zeolites by a solid state reaction. Interaction of copper compounds with H-mordenite or H-ZSM-5

The calcination of H-mordenite or H-ZSM-5 mixtures with CuO results in the migration of copper(II) ions into zeolite channels. The Cu 2+-ions which migrate from the outer surface of zeolite crystals are coordinated in the same positions as Cu 2+-cations introduced by ion-exchange. The majority of Cu(II) is located in H-ZSM-5 channels as isolated, coordinatively unsaturated, covalent-bonded Cu 2+-cations. The coordinative unsaturation of Cu 2+-ions is confirmed by the strong influence of O 2 adsorption on hyper-fine splitting (hfs) of e.s.r. spectra. The quantity of Cu 2+-cations which may be introduced in H-ZSM-5 by the solid state reaction is related linearly to the Al 3+ content in the zeolite lattice. The interaction of H-ZSM-5 with CuCl 2, CuF 2, Cu 3(PO 4) 2 or Cu 2S results in the migration of Cu(II) or Cu(I) ions in cationic positions of zeolite. So, the thermal stability of high-silica zeolite frameworks allows the introduction of some polyvalent ions in cationic positions by the solid state reaction.

Fast interstitial migration of copper(I) ions in Lil

Abstract The diffusion of the host cations as well as that of Cu+ and Cd2+ ions in dry polycrystaliine Lil was investigated by nmr-techniques (c.w. and pulsed T1 experiments) in the temperature range from - 100° up to +440°.

Some aspects of electromigration in D.C. electroluminescent ZnS devices

The stabilization with time of light emission from electroluminescent (EL) structures still requires investigation. Microscope observations of the EL structure show that the brightness is inhomogeneous and that the light emission is localized on many spots of different sizes. We investigated the distribution of the brightness along the active region of the sample and its dependence on time. The localized emission disappears with increasing time, and the brightness of the sample becomes more homogeneous although its intensity is reduced. This degration of the light emission is tentatively explained in terms of copper ion migration. The migration of copper ions affects the properties of the layer close to the positive electrode which appears bright. Some changes in the electrode surface and the precipitation of substantial amounts of copper were observed.

Direct Measurement of Interaction Energy between Solids and Gases. VII. Heats of Adsorption of Carbon Monoxide on Cu(II)-exchanged Zeolites Y

Abstract Differential heats of the adsorption of carbon monoxide on Cu(II)Y zeolites were calorimetrically determined. The heat of adsorption was larger on Cu(II)Y zeolites than on the NaY zeolite, and increased with the degree of Cu(II) ion-exchange. Repeated adsorption-desorption measurements revealed an increase in the heat of adsorption, which is considered to be due mainly to the migration of copper(II) ions from inaccessible sites for carbon monoxide to accessible ones in the process of adsorption-desorption.

X-ray diffraction study of cupric ion migrations in two Y-type zeolites containing adsorbed reagents

X-Ray diffraction study of two copper-exchanged Y zeolites (Cu 16Na 24Y and Cu 12Na 5H 27Y) in the dehydrated state showed that the cupric ions strongly prefer S I sites in the sodalite cages where they are firmly bonded to three framework oxygen atoms. The effect of sorbed molecules on the cation distribution was studied by adding ammonia, pyridine, naphthalene and butene to the dehydrated zeolite. Adsorption of a small amount of ammonia which can enter the sodalite cages produced slight but significant changes in the copper position. Addition of pyridine, naphthalene or butene induced an important migration of copper ions from S I and S I sites to the supercages where they can interact with sorbed molecules. The nature of the cation-organic molecule associations was investigated: infrared measurements and X-ray results provided evidence of a proton transfer from the organometallic complexes to the framework oxygen atoms.

The Critical Current Density for Copper Deposition and the Absolute Velocity of Migration of Copper Ions

The Critical Current Density for Copper Deposition and the Absolute Velocity of Migration of Copper Ions