The present disclosure relates to a process for fabricating a crystalline scintillator material with a structure of elpasolite type of theoretical composition A.sub.2BC.sub.(1-y)M.sub.yX.sub.(6-y) wherein: A is chosen from among Cs, Rb, K, Na, B is chosen from among Li, K, Na, C is chosen from among the rare earths, Al, Ga, M is chosen from among the alkaline earths, X is chosen from among F, Cl, Br, I, y representing the atomic fraction of substitution of C by M and being in the range extending from 0 to 0.05, comprising its crystallization by cooling from a melt bath comprising r moles of A and s moles of B, the melt bath in contact with the material containing A and B in such a way that 2s/r is above 1. The process shows an improved fabrication yield. Moreover, the crystals obtained can have compositions closer to stoichiometry and have improved scintillation properties.

Core-shell nanoparticles comprises a phosphorescent core and metal shell comprising at least two metals The phosphorescent core may comprise an up converting phosphor. The phosphorescent core may comprise a trivalent rare earth cation. The phosphorescent core further may comprise a monovalent alkali metal. The phosphorescent core may optionally comprises a second and also optionally a third trivalent rare earth cation.

Embodiments of the invention include a wavelength-converting material defined by AE.sub.3x1y+zRE.sub.3x2+yz[Si.sub.9wAl.sub.w(N.sub.1yC.sub.y).sup.[4](N.sub.16zwO.sub.z+w).sup.[2]]:Eu.sub.x1,Ce.sub.x2, where AE=Ca, Sr, Ba; RE=Y, Lu, La, Sc; 0x10.18; 0x20.2; x1+x2>0; 0y1; 0z3; 0w3.

Provided is a nanophosphor having a core/double shell structure, the nanophosphor including a upconversion core including a Yb.sup.3+, Ho.sup.3+, and Ce.sup.3+ co-doped fluoride-based nanophosphor represented by Formula 1; a first shell surrounding at least a portion of the upconversion core, and comprising a Nd.sup.3+ and Yb.sup.3+ co-doped fluoride-based crystalline composition represented by Formula 2; and a second shell surrounding at least a portion of the first shell, and having paramagnetic properties represented by Formula 3.

The present invention relates to a novel method for preparing a water-insoluble metal hydroxide, and a use thereof. The water-insoluble metal hydroxide of the present invention is conveniently and efficiently prepared s through the high-temperature heat treatment step two times and the washing step, and thus contains a small amount of an alkali metal and has a high crystallinity and a phase purity. The water-insoluble metal hydroxide of the present invention or metal oxide therefrom exhibits an absorption wavelength at a low wavelength range (for example, 490 nm or less) and a light emitting wavelength at a high wavelength range (for example, from 500 nm or more to less than 1,100 nm). Accordingly, the water-insoluble metal hydroxide of the present invention may be efficiently used in various applications such as a fire retardant, an antacid, an adsorbent and so forth, and may also be doped with another metal ion to be utilized as a raw material for fabricating a catalyst, a fluorescent material, an electrode material, a secondary battery material and the like.

The invention provides a lighting device comprising a lighting unit, wherein the lighting unit comprises a light source configured to generate light source light and a luminescent material configured to convert at least part of the light source light into luminescent material light, wherein the lighting device is configured to generate lighting device light comprising at least part of said luminescent material light, wherein the luminescent material is configured to provide said luminescent material light upon excitation by said light source light in an excitation band (EX) of said luminescent material, wherein the light source is configured to provide said light source light with a full width half maximum (FWHM) of equal to or less than 30 nm, and wherein said light source is configured to excite the luminescent material in an isosbestic point (IP) of said excitation band (EX).

Provided is a nanophosphor having a core/double shell structure, the nanophosphor including a upconversion core including a Yb.sup.3+, Ho.sup.3+, and Ce.sup.3+ co-doped fluoride-based nanophosphor represented by Formula 1; a first shell surrounding at least a portion of the upconversion core, and comprising a Nd.sup.3+ and Yb.sup.3+ co-doped fluoride-based crystalline composition represented by Formula 2; and a second shell surrounding at least a portion of the first shell, and having paramagnetic properties represented by Formula 3.

A halide material, such as scintillator crystals of LaBr.sub.3:Ce and SrI.sub.2:Eu, with a passivation surface layer is disclosed. The surface layer comprises one or more halides of lower water solubility than the scintillator crystal that the surface layer covers. A method for making such a material is also disclosed. In certain aspects of the disclosure, a passivation layer is formed on a surface of a halide material such as a scintillator crystal of LaBr.sub.3:Ce of SrI.sub.2:Eu by fluorinating the surface with a fluorinating agent, such as F.sub.2 for LaBr.sub.3:Ce and HF for SrI.sub.2:Eu.

A light emitting device includes a light source that emits a primary light having a light energy density exceeding 0.5W/mm.sup.2, and a first phosphor that absorbs the primary light to convert the primary light into a first wavelength-converted light having a wavelength longer than that of the primary light. The first phosphor includes a compound serving as a host, the compound being a simple oxide including one kind of metal element or a composite oxide including a plurality of different kinds of the simple oxide as an end member. When an energy conversion value at a peak wavelength of the primary light is E1 electron volts and an energy conversion value at a fluorescence peak wavelength of the first wavelength-converted light is E2 electron volts, a bandgap energy of a crystal of the simple oxide is larger than a sum of the E1 electron volts and the E2 electron volts.

The present disclosure relates to a process for fabricating a crystalline scintillator material with a structure of elpasolite type of theoretical composition A.sub.2BC.sub.(1-y)M.sub.yX.sub.(6-y) wherein: A is chosen from among Cs, Rb, K, Na, B is chosen from among Li, K, Na, C is chosen from among the rare earths, Al, Ga, M is chosen from among the alkaline earths, X is chosen from among F, Cl, Br, I,

y representing the atomic fraction of substitution of C by M and being in the range extending from 0 to 0.05, comprising its crystallization by cooling from a melt bath comprising r moles of A and s moles of B, the melt bath in contact with the material containing A and B in such a way that 2s/r is above 1. The process shows an improved fabrication yield. Moreover, the crystals obtained can have compositions closer to stoichiometry and have improved scintillation properties.