Nitridosilicates co-doped with zirconium and hafnium
AssigneeMerck Patent GmbH
InventorsHolger Winkler, Ralf Petry, Tim Vosgroene, Thomas Juestel, Dominik Uhlich, Danuta Dutczak
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Abstract
The invention relates to compounds of the formula (I) Ma2-y (Ca,Sr,Ba)1-x-ySi5-zMezN8:Eux Cey (I), where Ma=Li, Na and/or K Me=Hf4+ and/or Zr4+ x=0.0015 to 0.20 and y=0 to 0.15 z<4, and to a process for the preparation of these compounds and to the use as phosphors and conversion phosphors for conversion of the blue or near-UV emission from an LED.
Claims21
A compound of formula I
- Ma2-y(Ca,Sr,Ba)1-x-ySi5-zMezN8:EuxCey (I)
- where
- Ma=at least one of Li, Na and K
- Me=at least one of Hf4+ and Zr4+
- x=0.0015 to 0.20
- y=0 to 0.15 and
- z<4.
A compound of according to 1, which is obtainable by mixing a material containing silicon nitride, europium, cerium and at least one of calcium, strontium and barium with at least one co-dopant containing at least one of hafnium, zirconium, lithium, sodium and potassium by a solid-state diffusion method with subsequent thermal aftertreatment.
A shaped body comprising a compound of the
- 2-5-8 alkaline-earth metal siliconitride type with at least one of europium and cerium doping which additionally comprises at least one of hafnium, zirconium, lithium, sodium and potassium as co-dopants, and which
- A) has a rough surface which carries nanoparticles comprising at least one of SiO2, TiO2, Al2O3, ZnO, ZrO2 and Y2O3 or mixed oxides thereof or particles comprising a compound of the 2-5-8 alkaline-earth metal siliconitride type with or without one or more dopants from the series europium, cerium, hafnium, zirconium, lithium, sodium and potassium or particles comprising a compound of formula I
- Ma2-y(Ca,Sr,Ba)1-x-ySi5-zMezN8:EuxCey (I)
- where
- Ma=at least one of Li, Na and K
- Me=at least one of Hf4+ and Zr4+
- x=0.0015 to 0.20
- y=0 to 0.15 and
- z<4;
- or
- B) has a continuous surface coating which consists of at least one of SiO2, TiO2, Al2O3, ZnO, ZrO2 and Y2O3 or mixed oxides thereof or a compound of the 2-5-8 alkaline-earth metal siliconitride type with cerium doping which additionally comprises at least one of hafnium, zirconium, lithium, sodium and potassium as co-dopants, and which is without the activator europium;
- or
- C) has a porous surface coating which consists of at least one of SiO2, TiO2, Al2O3, ZnO, ZrO2 and Y2O3 or mixed oxides thereof or of a compound of the 2-5-8 alkaline-earth metal siliconitride type with or without one or more dopants from the series europium, cerium, hafnium, zirconium, lithium, sodium and potassium or a compound of formula I
- Ma2-y(Ca,Sr,Ba)1-x-ySi5-z,MezN8:EuxCey (I)
- where
- Ma=at least one of Li, Na and K
- Me=at least one of Hf4+ and Zr4+
- x=0.0015 to 0.20
- y=0 to 0.15 and
- z<4.
A shaped body comprising a compound of the 2-5-8 alkaline-earth metal siliconitride type with at least one of europium and cerium doping which additionally comprises at least one of hafnium, zirconium, lithium, sodium and potassium as co-dopants, wherein at least one of the co-dopants is hafnium or zirconium, whose surface carries functional groups which facilitate chemical or physical bonding to the environment.
Dependencies are inferred from the claim text.