Provided are: a composite of a silicate-based base material and a rare-earth compound, having high light-emitting intensity and capable of being used as light-emitting particles, light-emitting nanoparticle including the same, a cell detection method, a method for treating an animal, a medical device, and a method for producing the composite of a silicate-based base material and a rare-earth compound. This composite of a silicate-based base material and a rare-earth compound includes elemental silicon (Si) and elemental oxygen (O), the rare-earth compound comprising at least one selected from a chloride of a rare-earth element and a fluoride of a rare-earth element, the silicate-based base material having a solid .sup.29Si-NMR spectrum satisfying Q.sub.4/Q.sub.3 of 1.6 to 3.9 where Q.sub.4 represents a peak area derived from Si(OSi)4 and Q.sub.3 represents a peak area derived from HO—Si(OSi).sub.3.

The present invention relates to utilization of lanthanide time resolved fluorescence for determining silica concentration. In the method sample comprising silica is admixed with a reagent comprising a lanthanide (III) ion and optionally a chelating agent, silica in the sample is allowed to interact with the reagent comprising the lanthanide (III) ion, followed by exciting the sample and detecting a signal deriving from the lanthanide (III) ion, and determining the concentration of the silica in the sample by using the detected signal.

A light-emitting device is provided. The light emitting device includes a first electrode, second electrode facing the first electrode, and an emission layer between the first electrode and the second electrode. The emission layer includes at least one perovskite compound, a first quantum dot, and a second quantum dot. The first quantum dot and the second quantum dot may be different from each other.

The present invention aims at providing a scintillator for high temperature environments which has satisfactory light emission characteristics under high temperature environments; and a method for measuring radiation under high temperature environments. The scintillator for high temperature environments comprises a colquiriite-type crystal represented by the chemical formula LiM.sup.1M.sup.2X.sub.6 (where M.sup.1 is at least one alkaline earth metal element selected from Mg, Ca, Sr and Ba, M.sup.2 is at least one metal element selected from Al, Ga and Sc, and X is at least one halogen element selected from F, Cl, Br and I), for example, typified by LiCaAlF.sub.6, and the crystal optionally containing a lanthanoid element such as Ce or Eu. The method for measuring radiation under high temperature environments uses the scintillator.

A light-emitting device is provided. The light emitting device includes a first electrode, second electrode facing the first electrode, and an emission layer between the first electrode and the second electrode. The emission layer includes at least one perovskite compound, a first quantum dot, and a second quantum dot. The first quantum dot and the second quantum dot may be different from each other.