Anomalous Distribution of K-lsotopes During Countercurrent Electromigration in Molten ( L i,K )NO₃

Abstract

The previously presented theory that, in countercurrent electromigration of molten common anion binary mixtures, the lighter isotope of the less mobile cation should anoma lously enrich in a zone next to the anode, has been substan tiated for the K isotopes in molten (Li, K)N03.Until Lunden and Ljubimov's discovery of 'nonideal behaviour" some twenty years ago [1,2], it had generally been believed that, in countercurrent elec tromigration of pure or mixture melts with an initially uniform distribution along a separation tube, the lighter and heavier isotopes of the cation enrich only at the cathode and anode, respectively. They discov ered in countercurrent electromigration of molten (Li, K)(SO4)0 5 that on the anode side of the separa tion tube the gradient of 41K/39K is slightly positive before it becomes zero.In a previous paper [3] we have argued that in elec tromigration of molten systems consisting of two ca tions A and B and a common anion, enrichment of the lighter isotope of the less mobile cation B should oc cur in the region where dcB/dz < 0, where cB is con centration of B, and z is the distance taken from the anode towards the cathode. For more general cases, including temperature gradients, the reasons for such changes in composition in countercurrent electromi gration have been discussed by Klemm and Lunden [4] with essentially the same conclusion for the above mentioned case.Our argument was experimentally substantiated by enrichment of 6Li in the range where dcLj/dz < 0 in electromigration of molten binary mixtures (Li, K)C1 and (Li, K )N 0 3; the condition dcLi/dz < 0 was real Reprint requests to Prof. Isao Okada, Department of Elec tronic Chemistry, Tokyo Institute of Technology at Naga tsuta, Midori-ku, Yokohama.ized, if the Li+ ions were less mobile than the K + ions. In case where at low temperature the K + ions were less mobile, however, enrichment of 39K was not clearly detected (see Table 2 in [3]). This is presumably because the precision of the used mass spectrometer was not good enough.Thus, the purpose of the present work is to substan tiate our theoretical equations in [3] by showing ex perimentally that an anomalous enrichment of 39K actually occurs at the place where dcK/dz < 0; in the present work we have used a mass spectrometer with much better accuracy and precision.(Li, K )N 0 3 of the eutectic composition (mole frac tion of L iN 03, xLi = 0.58) was chosen. Since bu > bK below ca. 520 K [5], at lower temperatures K + ions are expected to enrich with respect to Li+ ions on the anode side in a separation tube, and there the condi tion of dcK/dz < 0 (and therefore d.xK/dz < 0) being realized, 39K should enrich in this region. Thus, electromigrations were performed at 450 K. The experi mental procedures were similar to those in the pre vious study [5], The separation tube was inserted into a large vessel containing catholytes of a mixture of (Li, K )N 0 3 of the eutectic composition + NH4N 0 3 (about 50mol% of the total mixture); since the tem perature of the electromigration wa...

Conductive Nanomaterials for Printed Electronics

“…Among them, poly( N -vinyl-2-pyrrolidone) (PVP) is the most frequently used for stabilizing metal NPs in various liquids and in Ag-and Cu-based ink formulations. [ 15,33,62,69,76,80,[84][85][86][87][88][89][90][91][92][93][94][95][96][97][98][99][100] This polymer strongly interacts with metal NPs through the oxygen atom of the carbonyl group. [ 101 ] In the case of charged polyelectrolytes, both electrostatic and steric mechanisms are simultaneously involved, resulting in electrosteric stabilization of the colloidal particles.…”

“…Typical solvents for metal-based inks are water, [ 16,26,100,157,166 ] hydrocarbons, [ 158,160,[167][168][169][170] alcohols and other oxygenated solvent. [ 33,84,168,[171][172][173] However, to tailor inkjet inks for optimal printing performance, the ink vehicles should usually be composed of a mixture of solvents, such as water with alcohols [ 85,86,89 ] and glycols, [ 76,82,98 ] as well as multicomponent mixtures containing water, organic solvents and glycerol. [ 85,86,95,107 ] Commercially available Agbased conductive inks with NPs size in the range of 2-200 nm and metal loading in the range of 10-60 wt% are now being produced by Cabot (USA), NovaCentrix (USA), Sun Chemicals (USA), NanoMas (USA), Applied Nanotech (USA), InkTec (Korea), Harima Chemicals (Japan), Advanced Nano Products (Korea), Samsung Electro-Mechanics (Korea), Cima NanoTech, PV Nano Cell and XJet Solar (Israel).…”

“…[ 33,84,168,[171][172][173] However, to tailor inkjet inks for optimal printing performance, the ink vehicles should usually be composed of a mixture of solvents, such as water with alcohols [ 85,86,89 ] and glycols, [ 76,82,98 ] as well as multicomponent mixtures containing water, organic solvents and glycerol. [ 85,86,95,107 ] Commercially available Agbased conductive inks with NPs size in the range of 2-200 nm and metal loading in the range of 10-60 wt% are now being produced by Cabot (USA), NovaCentrix (USA), Sun Chemicals (USA), NanoMas (USA), Applied Nanotech (USA), InkTec (Korea), Harima Chemicals (Japan), Advanced Nano Products (Korea), Samsung Electro-Mechanics (Korea), Cima NanoTech, PV Nano Cell and XJet Solar (Israel). A number of nanoparticulate Cu-based conductive inks containing 10-40 wt% metal (particles size 25-130 nm) are also produced by NovaCentrix (USA), Intrinsiq Materials (USA), Applied Nanotech (USA), and Samsung Electro-Mechanics (Korea).…”

“…[ 210,211 ] For example, resistors were printed by using UV-curable inks based on a poly(ethylene glycol) diacrylate (PEGDA) matrix and containing a dispersion of aqueous silver NPs (10 to 50 wt%). For resistors, the presence of a large amount of insulating materials from the surface of the NPs, and to obtain sintered metal coatings with resistivity comparable to that of bulk metal, for both, silver-based [ 1,73,[84][85][86]91,95,120,160,169,[214][215][216] and copper-based [ 33,73,76,88,96,109,217,218 ] inks. Figure 2 shows the typical changes in morphology of a silver printed layer after heating at various temperatures for 10 min.…”

High Enrichment of 6Li in Molten Nitrates by the Klemm Method

“…At x Li /x K = 0.427/0.573 at 380 • C, K + is more mobile than Li + , and consequently dc Li / dz becomes more negative with time, while dc K / dz becomes more positive. If dc/ dz > 0 and dc/ dz < 0, the heavier isotope and the lighter ones are enriched there, respectively [71]. Thus, 6 Li is enriched in the region dc/ dz < 0 except for the anode where dc/ dz ≈ +∞.…”