A method of growing a rare-earth oxyorthosilicate crystal, and crystals grown using the method are disclosed. The method includes preparing a melt by melting a first substance including at least one first rare-earth element and providing an atmosphere that includes an inert gas and a gas including oxygen.

Scintillating compounds, methods of synthesizing scintillating compounds, and applications of scintillating compounds are disclosed. The scintillating compounds can include cesium rare earth silicates. A scintillating compound can include cesium, silicon, oxygen, fluorine, and one or more of europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium and scandium. The scintillating compounds can form unit cells having the general formula Cs.sub.3RESi.sub.4O.sub.10F.sub.2 with RE including rare earth metals, lanthanides, and transition metals.

A dimmable light source for emitting white overall radiation may include a dimmer and a light-emitting diode. The dimmer may vary a current intensity of a current for operating the light-emitting diode during the operation of the light source. The LED may include a semiconductor layer sequence to emit primary radiation, and the LED may further include a conversion element configured to at least partially convert the primary radiation into secondary radiation having a first emission band with a first emission maximum ranging from 400 nm to 500 nm and a second emission band with a second emission maximum ranging from 510 nm to 700 nm. A relative intensity of the first emission band may reduce with decreasing current intensity of the current for operating the LED, and a relative intensity of the second emission band may increase with decreasing current intensity of the current for operating the LED.

A scintillation crystal can include a rare earth silicate, an activator, and a Group 2 co-dopant. In an embodiment, the Group 2 co-dopant concentration may not exceed 200 ppm atomic in the crystal or 0.25 at % in the melt before the crystal is formed. The ratio of the Group 2 concentration/activator atomic concentration can be in a range of 0.4 to 2.5. In another embodiment, the scintillation crystal may have a decay time no greater than 40 ns, and in another embodiment, have the same or higher light output than another crystal having the same composition except without the Group 2 co-dopant. In a further embodiment, a boule can be grown to a diameter of at least 75 mm and have no spiral or very low spiral and no cracks. The scintillation crystal can be used in a radiation detection apparatus and be coupled to a photosensor.

The present invention generally relates to a field emission light source and specifically to a field emission light source adapted to emit ultraviolet (UV) light. The light source has a UV emission member provided with an electron-excitable UV emitting material. The material is at least one of LuPO.sub.3:Pr.sup.3+, Lu.sub.2Si.sub.2O.sub.2:Pr.sup.3+, LaPO.sub.4:Pr.sup.3+, YBO.sub.3:Pr.sup.3+ and YPO.sub.4:Bi.sup.3+.

A light-emitting device 1 includes: a solid-state light-emitting element 10 that radiates a laser beam L; and a wavelength converter 50 including a plurality of types of phosphors which receive the laser beam L and radiate light. The phosphors 50 included in the wavelength converter are substantially composed of a Ce.sup.3+-activated phosphor. Then, output light of the light-emitting device 1 has a light component across a wavelength range of at least 420 nm or more and less than 700 nm. The light-emitting device 1 is capable of radiating light with high color rendering properties over a wide wavelength range.

A wavelength converter 100 includes: a first phosphor 1 composed of an inorganic phosphor activated by Ce.sup.3+; and a second phosphor 2 composed of an inorganic phosphor activated by Ce.sup.3+ and different from the first phosphor. At least one of the first phosphor and the second phosphor is particulate. The first phosphor and the second phosphor are bonded to each other by at least one of a chemical reaction in a contact portion between the compound that constitutes the first phosphor and a compound that constitutes the second phosphor and of adhesion between the compound that constitutes the first phosphor and the compound that constitutes the second phosphor.

Garnet silicate is garnet silicate containing, as a main component, silicate represented by a general formula: Lu.sub.2CaMg.sub.2(SiO.sub.4).sub.3. The garnet silicate includes primary particles having a particle shape derived from a crystal structure of garnet. Moreover, the garnet silicate further contains alkaline metal including at least lithium, in which a content of the alkaline metal is less than 2000 ppm. The garnet silicate phosphor includes garnet silicate and ions which are included in the garnet silicate and function as a light emission center. The wavelength converter includes the garnet silicate phosphor. A light emitting device includes the garnet silicate phosphor or the wavelength converter.

A scintillation crystal can include a rare earth silicate, an activator, and a Group 2 co-dopant. In an embodiment, the Group 2 co-dopant concentration may not exceed 200 ppm atomic in the crystal or 0.25 at in the melt before the crystal is formed. The ratio of the Group 2 concentration/activator atomic concentration can be in a range of 0.4 to 2.5. In another embodiment, the scintillation crystal may have a decay time no greater than 40 ns, and in another embodiment, have the same or higher light output than another crystal having the same composition except without the Group 2 co-dopant. In a further embodiment, a boule can be grown to a diameter of at least 75 mm and have no spiral or very low spiral and no cracks. The scintillation crystal can be used in a radiation detection apparatus and be coupled to a photosensor.

A phosphor is a phosphor composed by containing Ce.sup.3+ as an emission center in a matrix garnet compound having a garnet structure. Then, in the matrix garnet compound, a part of Ca that composes a crystal of Lu.sub.2CaMg.sub.2(SiO.sub.4).sub.3 is replaced by Mg. Moreover, a light emitting device includes the above-mentioned phosphor. In this way, it is possible to provide a garnet phosphor in which temperature quenching is reduced without largely shifting the light emission peak wavelength from that of a Lu.sub.2CaMg.sub.2(SiO.sub.4).sub.3:Ce.sup.3+ phosphor, and to provide a light emitting device using the garnet phosphor.