In a surface modification method for fluoride luminescent materials, an inorganic coating layer A.sub.xMF.sub.y coated substrate A.sub.xMF.sub.y:Mn.sup.4+ is mixed with an organic solution containing a metal phosphate, an alkoxysilane, an organic carboxylic acid or an organic amine. The solution is evaporated to give the organic-inorganic coating layer coated surface-modified fluoride luminescent material. The phosphor photoluminescence intensity and quantum efficiency of the modified phosphors can be maintained at 85%-95% under high temperature and high humidity conditions. After being coated with the inorganic coating layer, the surface defects of the phosphor are reduced, and the photoluminescence intensity and quantum yield of the phosphor are increased by 5%-15%. After being coated with the organic coating layer, the photoluminescence intensity of the phosphor is reduced <3%.

Compositions suitable for reversibly storing heat in thermal energy systems (TES) include a salt hydrate represented by the formula: MX.sub.q.nH.sub.2O. M is a cation selected from Groups 1 to 14 of the IUPAC Periodic Table, X is a halide of Group 17, q ranges from 1 to 4, and n ranges from 1 to 12. The cation (M) may have an electronegativity of ≤ about 1.8 and a molar mass ≤ about 28 g/mol. The anion (X) may have an electronegativity of ≥ about 2.9 to ≤ about 3.2. A distance between a cation (M) and coordinating water molecules (H.sub.2O) is ≤ about 2.1 Å. Thermal energy systems (TES) incorporating such compositions are also provided that are configured to reversibly store heat in the thermal energy system (TES) via an endothermic dehydration reaction and to release heat in in the thermal energy system (TES) via an exothermic hydration reaction.

Compositions suitable for reversibly storing heat in thermal energy systems (TES) include a salt hydrate represented by the formula: MX.sub.q.nH.sub.2O. M is a cation selected from Groups 1 to 14 of the IUPAC Periodic Table, X is a halide of Group 17, q ranges from 1 to 4, and n ranges from 1 to 12. The cation (M) may have an electronegativity of ≤ about 1.8 and a molar mass ≤ about 28 g/mol. The anion (X) may have an electronegativity of ≥ about 2.9 to ≤ about 3.2. A distance between a cation (M) and coordinating water molecules (H.sub.2O) is ≤ about 2.1 Å. Thermal energy systems (TES) incorporating such compositions are also provided that are configured to reversibly store heat in the thermal energy system (TES) via an endothermic dehydration reaction and to release heat in in the thermal energy system (TES) via an exothermic hydration reaction.

Provided is an active material for a fluoride-ion secondary battery, the active material containing a composite fluoride. The composite fluoride has a layered structure and is represented by a composition formula A.sub.mM.sub.nF.sub.x, where A is an alkali metal, M is a transition metal, 0<m≤2, 1≤n≤2, and 3≤x≤4. The alkali metal may be at least one kind selected from the group consisting of Na, K, Rb, and Cs. The transition metal may be a 3d transition metal.

Provided is an active material for a fluoride-ion secondary battery, the active material containing a composite fluoride. The composite fluoride has a layered structure and is represented by a composition formula A.sub.mM.sub.nF.sub.x, where A is an alkali metal, M is a transition metal, 0<m2, 1n2, and 3x4. The alkali metal may be at least one kind selected from the group consisting of Na, K, Rb, and Cs. The transition metal may be a 3d transition metal.

A process for purifying a manganese sulfate solution and precipitating high purity manganese sulfate monohydrate crystals. The concentration of manganese sulfate is increased and calcium and magnesium are removed by precipitating calcium and magnesium fluoride, which are separated from the concentrated solution to produce a clarified solution. In a first crystallization step, the clarified solution is combined with a recycled manganese sulfate solution and manganese sulfate seed crystals and the mixture is heated to produce a crystal suspension. Manganese sulfate crystals are separated and the remaining solution is used to prepare solid manganese fluoride, which is separated and returned to the process to remove calcium and magnesium. The manganese sulfate crystals are redissolved in water. Undissolved solids are removed to produce a second clarified manganese sulfate solution. In a second crystallization step the second clarified solution is combined with manganese sulfate monohydrate seed crystals, which are heated and mixed to produce a manganese sulfate monohydrate crystal product in a saturated manganese sulfate solution, from which the final high purity manganese sulfate monohydrate crystals are separated.

A process for purifying a manganese sulfate solution and precipitating high purity manganese sulfate monohydrate crystals. The concentration of manganese sulfate is increased and calcium and magnesium are removed by precipitating calcium and magnesium fluoride, which are separated from the concentrated solution to produce a clarified solution. In a first crystallization step, the clarified solution is combined with a recycled manganese sulfate solution and manganese sulfate seed crystals and the mixture is heated to produce a crystal suspension. Manganese sulfate crystals are separated and the remaining solution is used to prepare solid manganese fluoride, which is separated and returned to the process to remove calcium and magnesium. The manganese sulfate crystals are redissolved in water. Undissolved solids are removed to produce a second clarified manganese sulfate solution. In a second crystallization step the second clarified solution is combined with manganese sulfate monohydrate seed crystals, which are heated and mixed to produce a manganese sulfate monohydrate crystal product in a saturated manganese sulfate solution, from which the final high purity manganese sulfate monohydrate crystals are separated.

Ferromagnetic materials are disclosed that comprise at least one Dirac half metal material. In addition, Dirac half metal materials are disclosed, wherein the material comprises a plurality of massless Dirac electrons. In addition, ferromagnetic materials are disclosed that includes at least one Dirac half metal material, wherein the material comprises a plurality of massless Dirac electrons, wherein the material exhibits 100% spin polarization, and wherein the plurality of electrons exhibit ultrahigh mobility. Spintronic devices and heterostructures are also disclosed that include a Dirac half metal material.

Ferromagnetic materials are disclosed that comprise at least one Dirac half metal material. In addition, Dirac half metal materials are disclosed, wherein the material comprises a plurality of massless Dirac electrons. In addition, ferromagnetic materials are disclosed that includes at least one Dirac half metal material, wherein the material comprises a plurality of massless Dirac electrons, wherein the material exhibits 100% spin polarization, and wherein the plurality of electrons exhibit ultrahigh mobility. Spintronic devices and heterostructures are also disclosed that include a Dirac half metal material.

Ferromagnetic materials are disclosed that comprise at least one Dirac half metal material. In addition, Dirac half metal materials are disclosed, wherein the material comprises a plurality of massless Dirac electrons. In addition, ferromagnetic materials are disclosed that includes at least one Dirac half metal material, wherein the material comprises a plurality of massless Dirac electrons, wherein the material exhibits 100% spin polarization, and wherein the plurality of electrons exhibit ultrahigh mobility. Spintronic devices and heterostructures are also disclosed that include a Dirac half metal material.