Trivalent Al³⁺ Ion Conduction in Aluminum Tungstate Solid

Abstract

Ionic conduction of trivalent aluminum in solid aluminum tungstate, Al 2 (WO 4 ) 3 , has been directly and quantitatively demonstrated. Trivalent ions, especially for aluminum where the polarizability is considerably low, are strongly bonded in a crystal lattice and have been believed to be unlikely to exhibit migration in solids because of high electrostatic interaction with the surrounding skeleton structure. The material, Al 2 (WO 4 ) 3 , which has the Sc 2 (WO 4 ) 3 structure, was selected in order to reduce the interaction between the framework and the mobile species, Al 3+ , as much as possible. The ionic conduction characteristics of Al 2 (WO 4 ) 3 were investigated by means of electrolysis and electromotive force measurement by constructing an aluminum concentration cell. The typical electrical conductivity of Al 2 (WO 4 ) 3 was, approximately 2 × 10 -5 S cm -1 at 800 °C. The dc electrolysis data strongly support the conclusion that ionic Al 3+ is the mobile species in Al 2 (WO 4 ) 3 . By further electrochemical measurements, it was confirmed that the mobile species was aluminum ion in a trivalent state with no contribution due to electronic conduction. The ionic transference number was determined to be unity from the oxygen-air gas concentration cell and the aluminum concentration cell method.

Addition of Ceramic Barriers to Aluminum–Air Batteries to Suppress By-product Formation on Electrodes

“…During this study, we noticed that Al 2 (WO 3 ) 4 had an intrinsic electrical conductivity of nearly 4 × 10 −6 S cm −1 at 600 • C; however, its conductivity was not high at room temperature. 14 We found that the liquid electrolyte had penetrated the solid electrolyte region (the space between the ceramic particles), reaching the electrode. It was thus considered possible to fabricate a rechargeable aluminum-air battery with an insulating material, such as aluminum oxide, in order to replace the solid electrolyte.…”

Water-Insoluble Lanthanum Oxychloride-Based Solid Electrolytes with Ultra-High Chloride Ion Conductivity

“…[6] Treatment of FeCl 2 with C 5 Me 5 Li and then 2-chloro-4-methyl-7H-cyclopenta[b]pyridinyllithium affords ferrocene derivative 2. [7] Kumada coupling of 2 with MeMgBr furnishes 3, which is lithiated and then quenched with ClPPh 2 to provide ligand 1, the enantiomers of which are readily resolved by chiral HPLC. We have determined the absolute configuration of (À)-1 by X-ray crystallography.…”

Novel trivalent cation conducting solids and their application

“…Among the ion species conducting in solids, monovalent and divalent cations and anions are well known to migrate in solids. In 1995 [3], macro-scopic trivalent cation conduction is solids was demonstrated by us and after that, various trivalent cations such as A13+ [4] and rare earth cations [5][6][7], are proved to migrate in solids in such structures as Sc2(WO4)3 type [8] and NASICON type. Among various trivalent cations, A13+ is one of the most practically applicable cation species, and especially, (A10.2Zr0.8)20/19Nb(PO4)3 of the NASICON type [9], has been demonstrated to show as high ion conductivity as yttria stabilized zirconia (YSZ) [10] and calcia stabilized zirconia (CSZ) [10].…”