The invention relates to a method for obtaining a magnesium fluoride (MgF.sub.2) sol solution, comprising the steps of providing a magnesium alkoxide precursor in a non-aqueous solvent and adding 1.85 to 2.05 molar equivalents of non-aqueous hydrofluoric acid to said magnesium precursor, characterized in that the reaction proceeds in the presence of carbon dioxide. The invention further relates to sol solutions, method of applying the sol solutions of the invention to surfaces as a coating, and to antireflective coatings obtained thereby.

The invention relates to a method for obtaining a magnesium fluoride (MgF.sub.2) sol solution, comprising the steps of providing a magnesium alkoxide precursor in a non-aqueous solvent and adding 1.85 to 2.05 molar equivalents of non-aqueous hydrofluoric acid to said magnesium precursor, characterized in that the reaction proceeds in the presence of carbon dioxide. The invention further relates to sol solutions, method of applying the sol solutions of the invention to surfaces as a coating, and to antireflective coatings obtained thereby.

Compositions suitable for reversibly storing heat in thermal energy systems (TES) include a salt hydrate represented by the formula: MX.sub.q.Math.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 . 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.Math.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 . 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.

The invention relates to a method for obtaining a magnesium fluoride (MgF.sub.2) sol solution, comprising the steps of providing a magnesium alkoxide precursor in a non-aqueous solvent and adding 1.85 to 2.05 molar equivalents of non-aqueous hydrofluoric acid to said magnesium precursor, characterized in that the reaction proceeds in the presence of carbon dioxide. The invention further relates to sol solutions, method of applying the sol solutions of the invention to surfaces as a coating, and to antireflective coatings obtained thereby.

An object of the present disclosure is to provide a negative electrode active material for a fluoride-ion battery capable of improving battery capacity, and a method for manufacturing thereof. The negative electrode active material for a fluoride-ion battery of the present disclosure is represented by the following formula (1): Mg.sub.1xM.sup.III.sub.xF.sub.2+x (1), wherein, M.sup.III is a trivalent metal, and x is greater than 0 and less than 0.5. The method for the present disclosure for manufacturing a negative electrode active material comprises the following steps: providing raw materials comprising a magnesium fluoride and a fluoride of the trivalent metal, and applying mechanical impact to the raw materials to cause them to react.

An object of the present disclosure is to provide a negative electrode active material for a fluoride-ion battery capable of improving battery capacity, and a method for manufacturing thereof. The negative electrode active material for a fluoride-ion battery of the present disclosure is represented by the following formula (1): Mg.sub.1xM.sup.III.sub.xF.sub.2+x (1), wherein, M.sup.III is a trivalent metal, and x is greater than 0 and less than 0.5. The method for the present disclosure for manufacturing a negative electrode active material comprises the following steps: providing raw materials comprising a magnesium fluoride and a fluoride of the trivalent metal, and applying mechanical impact to the raw materials to cause them to react.

A ceramic-like structure includes: a transparent substrate; an ink layer; and a ceramic-like film layer. The ceramic-like film layer is disposed between the transparent substrate and the ink layer, and includes a first high-refractive-index material layer, a first low-refractive-index material layer, a second high-refractive-index material layer, and a second low-refractive-index material layer that are stacked on each other. Refractive indexes of the first high-refractive-index material layer and the second high-refractive-index material layer are greater than about 2.3, and refractive indexes of the first low-refractive-index material layer and the second low-refractive-index material layer are less than about 1.6.

A ceramic-like structure includes: a transparent substrate; an ink layer; and a ceramic-like film layer. The ceramic-like film layer is disposed between the transparent substrate and the ink layer, and includes a first high-refractive-index material layer, a first low-refractive-index material layer, a second high-refractive-index material layer, and a second low-refractive-index material layer that are stacked on each other. Refractive indexes of the first high-refractive-index material layer and the second high-refractive-index material layer are greater than about 2.3, and refractive indexes of the first low-refractive-index material layer and the second low-refractive-index material layer are less than about 1.6.

A window module includes: a window; a first anti-reflection layer disposed on the window; and a second anti-reflection layer disposed on the first anti-reflection layer, including magnesium fluoride and having a refractive index smaller than a refractive index of the first anti-reflection layer.