6451-21-4Relevant articles and documents
Solvent-free ageing reactions of rare earth element oxides: From geomimetic synthesis of new metal-organic materials towards a simple, environmentally friendly separation of scandium
Arhangelskis, Mihails,Fri??i?, Tomislav,Huski?, Igor
supporting information, p. 4364 - 4375 (2020/07/14)
The development of cleaner methodologies for the separation and processing of rare earth elements, including scandium and yttrium, is of high importance to materials science and industry. Here, we explore the use of simple, solvent-free and low-energy accelerated ageing reactions, inspired by geochemical processes of mineral weathering and neogenesis, to convert eight rare earth (RE) element oxides, specifically Sc, Y, La, Yb, Eu, Gd, Lu and Nd, into metal-organic oxalate derivatives. The reactions can readily be directed towards the formation of topologically distinct framework structures by introduction of additional oxalate ions in the form of simple alkaline metal or ammonium salts, providing not only simple, solvent-free access to novel metal-organic RE element architectures from readily accessible precursors, but also enabling a proof-of-principle of a simple route to separate scandium from at least seven other rare earth elements in a mixture of metal oxides. Specifically, the metal-organic structures obtained by ageing a mixture of scandium and other RE element oxides in presence of ammonium or sodium oxalates exhibit significant differences in aqueous solubility at boiling point of water, providing high scandium separation factors ranging from approximately 102-103, without requiring elaborate complexation reagents, toxic extractants, acidic media, or solvents other than water. This journal is
Proton conduction: Via lattice water molecules in oxalato-bridged lanthanide porous coordination polymers
Ishikawa, Ryuta,Ueno, Shunya,Yagishita, Sadahiro,Kumagai, Hitoshi,Breedlove, Brian K.,Kawata, Satoshi
, p. 15399 - 15405 (2016/10/13)
The proton conducting properties of two different structural types of porous coordination polymers [La2(ox)3(H2O)6]·4H2O (1) and [Er2(ox)3(H2O)6]·12H2O (2), where ox2- = oxalate, were investigated. 1 has a two-dimensional layered structure, whereas 2 has a three-dimensional structure. Both 1 and 2 have hydrophilic one-dimensional channels filled by lattice water molecules with hydrogen-bonding networks. The coordinated H2O molecules are Lewis acidic due to the lanthanoid ions donating protons to lattice-filling H2O molecules, thereby forming efficient proton conduction pathways. Alternating-current impedance analyses of 1 and 2 indicated significant proton conduction (σ = 3.35 × 10-7 S cm-1 at 368 K for 1, 1.79 × 10-6 S cm-1 at 363 K for 2 under RH = 100%, with Ea = 0.35 eV for 1 and 0.47 eV for 2), which was attributed to the Grotthuss mechanism via the lattice H2O molecules.
Non-isothermal studies of the decomposition course of lanthanum oxalate decahydrate
Balboul, Basma A.A.,El-Roudi,Samir, Ebthal,Othman
, p. 109 - 114 (2008/10/08)
The thermal decomposition of lanthanum oxalate hydrate La2 (C2O4)3·10H2O till 900°C, in air, is investigated by non-isothermal gravimetry and differential thermal analyses. Intermediates and final solid products were characterized by X-ray diffraction (XRD) and IR-spectroscopy, the results show that La2(C2O4) 3·10H2O dehydrates in stepwise at 86-360°C and decomposes to La2O3 at 710°C through different intermediates, La2(C2O4)3, La2O(CO3)2 and La2O2CO3, that form at 400, 425 and 470°C, respectively. The final product La2O3 obtained at 800 °C has a surface area of 13.4 m2/g. The activation energy, ΔE of the observed thermal processes is obtained by the non-isothermal method.
