A method includes forming a solution comprising a solvent and at least two elements selected from: scandium (Sc), yttrium (Y), one or more lanthanides, and one or more actinides. The method includes adding an effective amount of at least one polyoxometalate for forming complexes with at least one of the elements and adding an effective amount of a cation for causing precipitation of at least some of the complexes of one of the elements. Substantially all of another of the elements remains in solution during the precipitation of the at least some of the complexes of the one of the elements. A kit includes a polyoxometalate, a cation, and instructions for adding effective amounts of the polyoxometalate and the cation for separating at least two elements selected from the group consisting of: scandium (Sc), yttrium (Y), one or more lanthanides, and one or more actinides via a precipitation reaction.

The present invention relates to a rubidium fluoro-scandium borate compound, a rubidium fluoro-scandium borate nonlinear optical crystal, and a preparation method and application thereof. The rubidium fluoro-scandium borate compound has a chemical formula Rb.sub.2ScB.sub.3O.sub.6F.sub.2, does not contain a symmetry center and has a molecular weight of 382.33 g/mol. The rubidium fluoro-scandium borate nonlinear optical crystal belongs to the monoclinic crystal system, and belongs to the non-centrosymmetric space group P2.sub.1, and the unit cell parameters are: a=4.0372(10) , b=11.800(3) , c=8.823(2) , ==90, =98.327(11), Z=2. The present invention adopts a high-temperature vacuum packaging method or a solid-state synthesis method to prepare rubidium fluoro-scandium borate compounds. The present invention adopts a fluxing agent method to prepare a rubidium fluoro-scandium borate nonlinear optical crystal, which have the advantages of short absorption cutoff edge, large nonlinear optical effect, good thermal stability, and stable physical and chemical properties. The rubidium fluoro-scandium borate nonlinear optical crystal of the present invention can be used to fabricate nonlinear optical devices, which have important applications in fields such as optics, military, laser lithography, and communication, etc.

The removal of acid gases (e.g., non-carbon dioxide acid gases) using sorbents that include salts in molten form, and related systems and methods, are generally described.

Disclosed herein is a cathode for a lithium-ion battery having a formula:

Li.sub.2+u-vM.sub.2-u[XO.sub.4].sub.xO.sub.4(1-x) where, 0u1, 0v2 and 0x1, wherein M is a transition metal element of manganese or a mixture of manganese and iron, and X is an element of phosphorus, silicon, sulfur, boron, or a mixture of these elements.

A product, in accordance with one embodiment, includes at least one polyoxometalate in at least an effective amount that, when combined with a solution comprising a solvent and at least two elements selected from the group consisting of: scandium (Sc), yttrium (Y), one or more lanthanides, and one or more actinides, forms complexes with at least one of the elements. The product also includes a cation in at least an effective amount that when combined with the solution having the at least one polyoxometalate therein, causes precipitation of at least some of the complexes of one of the elements such that substantially all of another of the elements remains in the solution during precipitation.