Disclosed is a fluorescent plate in which a high reflectance of a reflective layer can be maintained over a long period of time, and occurrence of peeling of the reflective layer can be suppressed.

The fluorescent plate of the present invention includes a fluorescent material layer containing a fluorescent material, an oxide layer disposed below the fluorescent material layer, and a reflective layer which is disposed below the oxide layer and is formed of silver, and further includes an oxidation-preventive protective layer which is disposed between the oxide layer and the reflective layer and is formed of a translucent material, and a translucent adhesion layer interposed between the oxidation-preventive protective layer and the reflective layer.

A fluoride ion conductor contains rubidium, magnesium, and fluorine. In an average composition of the fluoride ion conductor, the ratio of the number of moles of the magnesium to the total number of moles of the rubidium and the magnesium is less than 0.4.

A main object of the present disclosure is to provide an anode material that is used in a fluoride ion battery and can prevent the decrease in operating voltage while inhibiting occurrence of short circuit. The present disclosure achieves the object by providing an anode material to be used in a fluoride ion battery, the anode material comprising a Mg material containing a Mg element, and a fluoride ion conductive material containing at least one kind of metal element excluding a Mg element, and a F element.

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.

An object of the present disclosure is to provide a fluoride-ion battery capable of achieving high charge and discharge capacities. The fluoride-ion battery of the present disclosure comprises a positive electrode active material layer, a negative electrode active material layer, and an electrolyte layer formed between the positive electrode active material layer and the negative electrode active material layer. In the fluoride-ion battery of the present disclosure, the negative electrode active material layer contains metallic magnesium, magnesium fluoride, and calcium barium fluoride, wherein a mass ratio of metallic magnesium to magnesium fluoride is 0.1 to 10.0.

An object of the present disclosure is to provide a fluoride-ion battery capable of achieving high charge and discharge capacities. The fluoride-ion battery of the present disclosure comprises a positive electrode active material layer, a negative electrode active material layer, and an electrolyte layer formed between the positive electrode active material layer and the negative electrode active material layer. In the fluoride-ion battery of the present disclosure, the negative electrode active material layer contains metallic magnesium, magnesium fluoride, and calcium barium fluoride, wherein a mass ratio of metallic magnesium to magnesium fluoride is 0.1 to 10.0.

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, characterized in that the reaction proceeds in the presence of a second magnesium fluoride precursor selected from the group of salts of strong, volatile acids, such as a chloride, bromide, iodide, nitrate or triflate of magnesium, or of a catalytic amount of a strong, volatile acid; and/or an additive non-magnesium fluoride precursor selected from the group of salts of strong, volatile acids, such as a chloride, bromide, iodide, nitrate or triflate of lithium, antimony, tin calcium, strontium, barium, aluminum, silicon, zirconium, titanium or zinc. 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.

A positive electrode active material includes: a particle including a lithium composite oxide; a first layer that is provided on a surface of the particle and includes a lithium composite oxide; and a second layer that is provided on a surface of the first layer. The lithium composite oxide included in the particle and the lithium composite oxide included in the first layer have the same composition or almost the same composition, the second layer includes an oxide or a fluoride, and the lithium composite oxide included in the first layer has lower crystallinity than the lithium composite oxide included in the particle.

A positive electrode active material includes: a particle including a lithium composite oxide; a first layer that is provided on a surface of the particle and includes a lithium composite oxide; and a second layer that is provided on a surface of the first layer. The lithium composite oxide included in the particle and the lithium composite oxide included in the first layer have the same composition or almost the same composition, the second layer includes an oxide or a fluoride, and the lithium composite oxide included in the first layer has lower crystallinity than the lithium composite oxide included in the particle.