PHOSPHORS AND PHOSPHOR-CONVERTED LEDS

Abstract

The present invention relates to pyrosilicate phosphors, to a process for the preparation thereof and to the use thereof as conversion phosphors. The present invention also relates to an emission-converting material comprising the conversion phosphor according to the invention, and to the use thereof in light sources, in particular pc-LEDs (phosphor converted light emitting devices). The present invention furthermore relates to light sources, in particular pc-LEDs, and to lighting units which comprise a primary light source and the emission-converting material according to the invention.

Claims

1. Compound of formula (1),
(Ba.sub.2-a-b-c-dM.sub.aA.sub.bRE.sub.cD.sub.d)(Mg.sub.1-e-f-g-jM.sub.eA.sub.fRE.sub.gC.sub.j)(Si.sub.2-h-iB.sub.hC.sub.i)(O.sub.7+m-k-lX.sub.kN.sub.l) Formula (1) where the following applies to the symbols and indices used: M is selected from the group consisting of Ca, Sr, Zn or mixtures of these elements; A is selected from the group consisting of Na, K, Rb or mixtures of these elements; RE is selected from the group consisting of La, Y, Gd or mixtures of these elements; D is selected from the group consisting of Eu.sup.2+, Mn.sup.2+, Yb.sup.2+, Sm.sup.2+ or mixtures of these elements; M is selected from the group consisting of Zr, Hf or mixtures of these elements; A is selected from the group consisting of Li, Na or mixtures of these elements; RE is selected from the group consisting of Sc, Lu or mixtures of these elements; C is selected from the group consisting of B, Al, Ga, In or mixtures of these elements; B is selected from the group consisting of Ge, Sn or mixtures of these elements; C is selected from the group consisting of B, Al, Ga, In or mixtures of these elements; X is selected from the group consisting of F, Cl or mixtures of these elements; N is nitrogen; 0a1.0; 0b0.6; 0c0.6; 0d2.0; 0e0.3; 0f0.3; 0g0.3; 0j0.6; 0h1.0; 0i0.6; 0k2.1; 012.1; and 2.0m2.0; with the proviso that b0 and/or c0 and/or e0 and/or g0 and/or with the proviso that f0 and k0 at the same time and/or with the proviso that f0 and j and/or i0 at the same time.

2. Compound according to claim 1 wherein the following applies for the indices used: 0a0.6; 0b0.4; 0c0.4; 0d1.0; 0e0.2; 0f0.2; 0g0.2; 0j0.4; 0h0.6; 0i0.4; 0k1.4; 011.4; and 1.0m1.0; with the proviso that b0 and/or c0 and/or e0 and/or g0 and/or with the proviso that f0 and k0 at the same time and/or with the proviso that f0 and j and/or i0 at the same time.

3. Compound according to claim 1, wherein the following applies to the indices used: 0a0.4; 0b0.2; 0c0.2; 0.01d0.2; 0e0.1; 0f0.1; 0g0.1; 0j0.2; 0h0.4; 0i0.2; 0k0.7; 010.7; 0.5m0.5; with the proviso that b0 and/or c0 and/or e0 and/or g0 and/or with the proviso that f0 and k0 at the same time and/or with the proviso that f0 and j and/or i0 at the same time.

4. Compound according to claim 1, characterised in that a maximum of three of the indices a, b, c, e, f, g, j, h, I, k and l is 0.

5. Compound according to claim 1, characterised in that a maximum of two of the indices a, b, c, e, f, g, j, h, I, k and l is 0.

6. Compound according to claim 1, selected from the compounds of formula (2),
(Ba.sub.2-a-b-c-dM.sub.aK.sub.bLa.sub.cE.sub.d)(Mg.sub.1-e-f-g-jZr.sub.eLi.sub.fSc.sub.gC.sub.j)(Si.sub.2-h-iGe.sub.hC.sub.i)(O.sub.7+m-k-lX.sub.kN.sub.l) Formula (2) where the following applies for the symbols and indices used: M is selected from the group consisting of Ca, Sr or mixtures of these elements; C is selected from the group consisting of Al, Ga or mixtures of these elements; C is selected from the group consisting of Al, Ga or mixtures of these elements; X is selected from the group consisting of F, Cl or mixtures of these elements; N is nitrogen; 0a0.4; 0b0.2; 0c0.2; 0.005d0.4, more preferably 0.01d0.2; 0e0.1; 0f0.1; 0g0.1; 0j0.2; 0h0.4; 0i0.2; 0k0.7; 010.7; 0.5m0.5; with the proviso that b0 and/or c0 and/or e0 and/or g0 and/or with the proviso that f0 and k0 at the same time and/or with the proviso that f0 and j and/or i0 at the same time.

7. Compound according to claim 1, selected from the compounds of formulae (3) to (13),
(Ba.sub.2-b-dA.sub.bD.sub.d)MgSi.sub.2(O.sub.7-bX.sub.b)Formula (3)
(Ba.sub.2-b-dA.sub.bD.sub.d)(Mg.sub.1-bRE.sub.b)Si.sub.2O.sub.7Formula (4)
(Ba.sub.2-b-dA.sub.bD.sub.d)MgSi.sub.2O.sub.7-0.5bFormula (5)
(Ba.sub.2-c-dRE.sub.cD.sub.d)MgSi.sub.2(O.sub.7-cN.sub.c)Formula (6)
(Ba.sub.2-dD.sub.d)(Mg.sub.1-gRE.sub.g)Si.sub.2(O.sub.7-gN.sub.g)Formula (7)
(Ba.sub.2-dD.sub.d)(Mg.sub.1-eM.sub.e)Si.sub.2O.sub.7+eFormula (8)
(Ba.sub.2-d-0.5eD.sub.d)(Mg.sub.1-eM.sub.e)Si.sub.2O.sub.7+0.5eFormula (9)
(Ba.sub.2-dD.sub.d)(Mg.sub.1-fA.sub.f)Si.sub.2(O.sub.7-fX.sub.f)Formula (10)
(Ba.sub.2-dD.sub.d)(Mg.sub.1-2fA.sub.fC.sub.f)Si.sub.2O.sub.7Formula (11)
(Ba.sub.2-dD.sub.d)(Mg.sub.1-fA.sub.f)(Si.sub.2-fC.sub.f)O.sub.7Formula (12)
(Ba.sub.2-dD.sub.d)(Mg.sub.1-2eM.sub.eRE.sub.e)Si.sub.2(O.sub.7-eN.sub.e)Formula (13) where the symbols and indices have the meanings given in claim 1 and furthermore: b0 in formula (3), (4) and (5), c0 in formula (6), g0 in formula (7), e0 in formula (8) and (9), f0 in formula (10), (11) and (12), and e0 in formula (13).

8. Compound according to claim 1, selected from the compounds of formulae (3a) to (13a),
(Ba.sub.2-b-dK.sub.bEu.sub.d)MgSi.sub.2(O.sub.7-bF.sub.b)Formula (3a)
(Ba.sub.2-b-dK.sub.bEu.sub.d)MgSi.sub.2(O.sub.7-bCl.sub.b)Formula (3b)
(Ba.sub.2-b-dK.sub.bEu.sub.d)(Mg.sub.1-bSc.sub.b)Si.sub.2O.sub.7Formula (4a)
(Ba.sub.2-b-dK.sub.bEu.sub.d)MgSi.sub.2O.sub.7-0.5bFormula (5a)
(Ba.sub.2-c-dLa.sub.cEu.sub.d)MgSi.sub.2(O.sub.7-cN.sub.c)Formula (6a)
(Ba.sub.2-dEu.sub.d)(Mg.sub.1-gSc.sub.g)Si.sub.2(O.sub.7-gN.sub.g)Formula (7a)
(Ba.sub.2-dEu.sub.d)(Mg.sub.1-eZr.sub.e)Si.sub.2O.sub.7+eFormula (8a)
(Ba.sub.2-d-0.5eEu.sub.d)(Mg.sub.1-eZr.sub.e)Si.sub.2O.sub.7+0.5eFormula (9a)
(Ba.sub.2-dEu.sub.d)(Mg.sub.1-fLi.sub.f)Si.sub.2(O.sub.7-fF.sub.f)Formula (10a)
(Ba.sub.2-dEu.sub.d)(Mg.sub.1-fLi.sub.f)Si.sub.2(O.sub.7-fCl.sub.f)Formula (10b)
(Ba.sub.2-dEu.sub.d)(Mg.sub.1-2fLi.sub.fAl.sub.f)Si.sub.2O.sub.7Formula (11a)
(Ba.sub.2-dEu.sub.d)(Mg.sub.1-2fLi.sub.fGa.sub.f)Si.sub.2O.sub.7Formula (11b)
(Ba.sub.2-dEu.sub.d)(Mg.sub.1-fLi.sub.f)(Si.sub.2fAl.sub.f)O.sub.7Formula (12a)
(Ba.sub.2-dEu.sub.d)(Mg.sub.1-fLi.sub.f)(Si.sub.2-fGa.sub.f)O.sub.7Formula (12b)
(Ba.sub.2-dEu.sub.d)(Mg.sub.1-2eZr.sub.eSc.sub.e)Si.sub.2(O.sub.7-eN.sub.e)Formula (13a) where the symbols and indices have the meanings given in claim 1 and furthermore: b0 in formula (3a), (3b), (4a) and (5a), c0 in formula (6a), g0 in formula (7a), e0 in formula (8a) and (9a), f0 in formula (10a), (10b), (11a), (11b), (12a) and (12b), and e0 in formula (13a).

9. Compound according to claim 1, characterised in that the compound is coated.

10. Process for the preparation of a compound according to claim 1, comprising the steps: a) preparation of a mixture comprising all elements, which should be incorporated into the compound; and b) calcination of the mixture at elevated temperature.

11. Process according to claim 10, characterised in that a fluxing agent is used, which is selected from the group of ammonium halides, alkaline-earth metal fluorides, carbonates, alkoxides, oxalates and/or boric acid.

12. A conversion phosphor, in particular for the partial or complete conversion of the violet or near-UV emission of a light-emitting diode into light having a longer wavelength, which comprises a compound of claim 1.

13. Light source which comprises at least one primary light source and at least one compound according to claim 1.

14. Light source according to claim 13, wherein the primary light source is a luminescent indium aluminium gallium nitride or a luminescent arrangement based on ZnO, TCO (transparent conducting oxide) or SiC, or a near-UV or violet laser, or a source which exhibits electroluminescence and/or photoluminescence, or a plasma or discharge source.

15. Lighting unit, in particular for the backlighting of display devices, characterised in that it comprises at least one light source according to claim 13.

Description

EXAMPLES

[0157] The phase formation of the samples was in each case checked by means of X-ray diffractometry. For this purpose, a Rigaku Miniflex II X-ray diffractometer with Bragg-Brentano geometry was used. The radiation source used was an X-ray tube with Cu-K radiation (=0.15418 nm). The tube was operated at a current strength of 15 mA and a voltage of 30 kV. The measurement was carried out in an angle range of 10-80 at 10.Math.min.sup..

[0158] Reflection spectra were determined using an Edinburgh Instruments Ltd. fluorescence spectrometer. For this purpose, the samples were placed and measured in a BaSO.sub.4-coated integrating sphere. Reflection spectra were recorded in a range from 250-800 nm. The white standard used was BaSO.sub.4 (Alfa Aesar 99.998%). A 450 W Xe lamp was used as excitation source.

[0159] The excitation spectra and emission spectra were recorded using an Edinburgh Instruments Ltd. fluorescence spectrometer fitted with mirror optics for powder samples. The excitation source used was a 450 W Xe lamp.

Synthesis of Inventive Compounds

Example 1: Synthesis of Ba.SUB.1.90.Eu.SUB.0.10.MgSi.SUB.2.O.SUB.7.Comparative Example

[0160] 112.49 g BaCO.sub.3

[0161] 29.14 g Mg.sub.5(CO.sub.3).sub.4(OH).sub.2

[0162] 5.28 g Eu.sub.2O.sub.3

[0163] 37.20 g SiO.sub.2

[0164] 1.60 g NH.sub.4Cl

[0165] The starting materials are mixed by ball milling for 2 hours and fired at 1100 C. for 6 h in an H.sub.2:N.sub.2 (70:30) atmosphere. After firing, the material is ground into a fine powder, washed in water, dried and sieved using a 50 m nylon sieve to narrow the particle size range. The resulting compound shows an emission maximum at 512 nm (CIE x=0.252; y=0.514).

Example 2: Synthesis of Ba.SUB.1.85.K.SUB.0.05.Eu.SUB.0.10.MgSi.SUB.2.O.SUB.6.95.Cl.SUB.0.05

[0166] 14.60 g BaCO.sub.3

[0167] 0.15 g K.sub.2CO.sub.3x0.5H.sub.2O

[0168] 3.89 g Mg.sub.5(CO.sub.3).sub.4(OH).sub.2

[0169] 0.70 g Eu.sub.2O.sub.3

[0170] 4.96 g SiO.sub.2

[0171] 0.21 g NH.sub.4Cl

[0172] The starting materials are mixed in a mechanical mortar for 20 minutes and fired at 1100 C. for 6 h in an H.sub.2:N.sub.2 (70:30) atmosphere. After firing, the material is ground into a fine powder, washed in water, dried and sieved using a 50 m nylon sieve to narrow the particle size range. The resulting compound shows an emission maximum at 518 nm (CIE x=0.273; y=0.521).

Example 3: Synthesis of Ba.SUB.1.85.K.SUB.0.05.Eu.SUB.0.10.MgSi.SUB.2.O.SUB.6.95.F.SUB.0.05

[0173] 14.60 g BaCO.sub.3

[0174] 0.12 g KF

[0175] 3.89 g Mg.sub.5(CO.sub.3).sub.4(OH).sub.2

[0176] 0.70 g Eu.sub.2O.sub.3

[0177] 4.96 g SiO.sub.2

[0178] 0.21 g NH.sub.4Cl

[0179] The starting materials are mixed in a mechanical mortar for 20 minutes and fired at 1100 C. for 6 h in an H.sub.2:N.sub.2 (70:30) atmosphere. After firing, the material is ground into a fine powder, washed in water, dried and sieved using a 50 m nylon sieve to narrow the particle size range. The resulting compound shows an emission maximum at 516 nm (CIE x=0.260; y=0.520).

Example 4: Synthesis of Ba.SUB.1.90.Eu.SUB.0.10.Mg.SUB.0.95.Li.SUB.0.05.Si.SUB.2.O.SUB.6.95.Cl.SUB.0.05

[0180] 15.00 g BaCO.sub.3

[0181] 0.07 g Li.sub.2CO.sub.3

[0182] 3.69 g Mg.sub.5(CO.sub.3).sub.4(OH).sub.2

[0183] 0.70 g Eu.sub.2O.sub.3

[0184] 4.96 g SiO.sub.2

[0185] 0.21 g NH.sub.4Cl

[0186] The starting materials are mixed in a mechanical mortar for 20 minutes and fired at 1100 C. for 6 h in an H.sub.2:N.sub.2 (70:30) atmosphere. After firing, the material is ground into a fine powder, washed in water, dried and sieved using a 50 m nylon sieve to narrow the particle size range. The resulting compound shows an emission maximum at 513 nm (CIE x=0.253; y=0.517).

Example 5: Synthesis of Ba.SUB.1.90.Eu.SUB.0.10.Mg.SUB.0.95.Li.SUB.0.05.Si.SUB.2.O.SUB.6.95.F.SUB.0.05

[0187] 15.00 g BaCO.sub.3

[0188] 0.07 g Li.sub.2CO.sub.3

[0189] 3.69 g Mg.sub.5(CO.sub.3).sub.4(OH).sub.2

[0190] 0.70 g Eu.sub.2O.sub.3

[0191] 4.96 g SiO.sub.2

[0192] 0.21 g NH.sub.4Cl

[0193] 0.21 g BaF.sub.2

[0194] The starting materials are mixed in a mechanical mortar for 20 minutes and fired at 1100 C. for 6 h in an H.sub.2:N.sub.2 (70:30) atmosphere. After firing, the material is ground into a fine powder, washed in water, dried and sieved using a 50 m nylon sieve to narrow the particle size range. The resulting compound shows an emission maximum at 518 nm (CIE x=0.272; y=0.528).

Example 6: Synthesis of Ba.SUB.1.90.Eu.SUB.0.10.Mg.SUB.0.80.Li.SUB.0.1.Al.SUB.0.1.Si.SUB.2.O.SUB.7

[0195] 15.00 g BaCO.sub.3

[0196] 0.15 g Li.sub.2CO.sub.3

[0197] 3.11 g Mg.sub.5(CO.sub.3).sub.4(OH).sub.2

[0198] 0.70 g Eu.sub.2O.sub.3

[0199] 4.96 g SiO.sub.2

[0200] 0.21 g NH.sub.4Cl

[0201] 0.20 g A.sub.2O.sub.3

[0202] The starting materials are mixed in a mechanical mortar for 20 minutes and fired at 1100 C. for 6 h in an H.sub.2:N.sub.2 (70:30) atmosphere. After firing, the material is ground into a fine powder, washed in water, dried and sieved using a 50 m nylon sieve to narrow the particle size range. The resulting compound shows an emission maximum at 521 nm (CIE x=0.289; y=0.527).

Example 7: Synthesis of Ba.SUB.1.9.Eu.SUB.0.10.Mg.SUB.0.95.Zr.SUB.0.05.Si.SUB.2.O.SUB.7.05

[0203] 15.00 g BaCO.sub.3

[0204] 3.69 g Mg.sub.5(CO.sub.3).sub.4(OH).sub.2

[0205] 0.70 g Eu.sub.2O.sub.3

[0206] 4.96 g SiO.sub.2

[0207] 0.21 g NH.sub.4Cl

[0208] 0.25 g ZrO.sub.2

[0209] The starting materials are mixed in a mechanical mortar for 20 minutes and fired at 1050 C. for 14 h in an H.sub.2:N.sub.2 (70:30) atmosphere. After firing, the material is ground into a fine powder, washed in water, dried and sieved using a 50 m nylon sieve to narrow the particle size range. The resulting compound shows an emission maximum at 516 nm (x=0.260; y=0.515).

Example 8: Synthesis of Ba.SUB.1.90.Eu.SUB.0.10.Mg.SUB.0.95.Sc.SUB.0.05.Si.SUB.2.O.SUB.7.025

[0210] 7.499 g BaCO.sub.3

[0211] 1.845 g Mg.sub.5(CO.sub.3).sub.4(OH).sub.2

[0212] 0.352 g Eu.sub.2O.sub.3

[0213] 2.463 g SiO.sub.2

[0214] 0.107 g NH.sub.4Cl

[0215] 0.069 g Sc.sub.2O.sub.3

[0216] The starting materials are mixed in a mechanical mortar for 20 minutes and fired at 1100 C. for 6 h in an H.sub.2:N.sub.2 (70:30) atmosphere. After firing, the material is ground into a fine powder, washed in water, dried and sieved using a 50 m nylon sieve to narrow the particle size range. The resulting compound shows an emission maximum at 512 nm (CIE x=0.255, y=0.498).

Example 9: Synthesis of Ba.SUB.1.86.Eu.SUB.0.10.La.SUB.0.04.MgSi.SUB.2.O.SUB.7.02

[0217] 11.779 g BaCO.sub.3

[0218] 3.185 g Mg.sub.5(CO.sub.3).sub.4(OH).sub.2

[0219] 0.577 g Eu.sub.2O.sub.3

[0220] 4.040 g SiO.sub.2

[0221] 0.175 g NH.sub.4Cl

[0222] 0.214 g La.sub.2O.sub.3

[0223] The starting materials are mixed in a mechanical mortar for 20 minutes and fired at 1100 C. for 6 h in an H.sub.2:N.sub.2 (70:30) atmosphere. After firing, the material is ground into a fine powder, washed in water, dried and sieved using a 50 m nylon sieve to narrow the particle size range. The resulting compound shows an emission maximum at 512 nm (CIE x=0.255, y=0.507).

Example 10: Thermal Quenching Behaviour

[0224] The thermal quenching behaviour of the inventive compounds was investigated by measuring the emission efficiency at 150 C. and comparing it to the efficiency at room temperature. The results are summarized in Table 1.

TABLE-US-00001 TABLE 1 Thermal quenching behaviour Efficiency at 150 C. Example (compared to r.t.) Ba.sub.2MgSi.sub.2O.sub.7: Eu * 50% 2 87% 4 85% 6 72% 7 95% * value according to J. Van et al., J. Mater. Chem. C 2, 2014, 8328.

Example 11: LED Examples

[0225] General Instructions for Manufacturing and Measurement of Phosphor-Converted-LEDs (pc-LEDs):

[0226] A mass of m.sub.p,n (where the index n denotes the number of the phosphor component of the phosphor blend related to the particular LED-example), of the phosphor component mentioned in the particular LED-example, is weighed together with the other phosphor components (masses of m.sub.p,n, n>1) and subsequently mixed (e. g. by use of a planetary centrifugal mixer). To the phosphor blend obtained by the process mentioned before, a mass of m.sub.Silicone of an optical transparent silicone is added and subsequently homogenously mixed by means of a planetary centrifugal mixer, in order to obtain a phosphor concentration of c.sub.p (in % by mass) in the whole mass of the Silicone-phosphor slurry. The slurry is then dispensed onto a blue or near-UV or UV- or violet-light-emitting LED-dye by means of an automated dispensing equipment and cured under elevated temperatures, depending on the properties of the used transparent Silicone. The LED-dyes used in the examples mentioned below emit visible violet light at a wavelength of 407 nm or 411 nm, respectively and are driven at an operating current of 350 mA. The lighting-technology-related parameters are obtained by means of a spectrometer from Instrument Systems, type CAS 140 CT combined with an Integration sphere ISP 250. The characterization of the pc-LED is performed by measurement of the wavelength-dependent spectral power density. The spectrum of the emitted light from the pc-LED is then used for the calculation of colour coordinates x and y (CIE 19312-degree observer), photometric fluxes .sub.v, Correlated Colour Temperature (CCT) and the Colour Rendering Index (CRI).

TABLE-US-00002 TABLE 2 Phosphor components for LED manufacturing. Phosphor component no. Phosphor designation 1 Sr.sub.2.5Eu.sub.0.12Ca.sub.0.38MgSi.sub.2O.sub.8 2 Ba.sub.1.9Eu.sub.0.1Mg.sub.0.95Zr.sub.0.05Si.sub.2O.sub.7.05* 3 CaAlSiN.sub.3: Eu *according to Example 7

TABLE-US-00003 TABLE 3 LED manufacturing examples. Refer to Table 2 for the specific components. Parameter LED example a LED example b peak-wavelength 407 410 of LED dye m.sub.p, 1/g 1.52 1.52 m.sub.p, 2/g 3.05 3.05 m.sub.p, 3/g 0.23 0.23 m.sub.Silicone/g 5.20 5.20 c.sub.p/wt. % 48 48 CIE x 0.431 0.431 CIE y 0.408 0.400 CCT/K 3133 3076 CRI 89 89 .sub.v/lm 41 41

DESCRIPTION OF THE FIGURES

[0227] FIG. 1: Emission spectra of different Ba-pyrosilicate modifications under a 410 nm excitation, showing spectral shift of the emission band depending on composition compared to the inventive compound of Example 1.

[0228] FIG. 2: Excitation spectrum of Ba-pyrosilicate modification of Example 7 monitoring the emission at 517 nm.

[0229] FIG. 3: Temperature quenching (TQ) profile of the typical modification of the Ba-pyrosilicate of Example 7 under 410 nm excitation (see Example 10 for comparison with the literature data).

[0230] FIG. 4: Emission spectra of Sc- and La-modified Ba-pyrosilicate modifications according to Examples 8 and 9 under a 410 nm excitation (note: the spectra overlay each other almost perfectly).

[0231] FIG. 5: Spectrum of the LED of LED example a (407 nm violet LED chip).

[0232] FIG. 6: Spectrum of the LED of LED example b (410 nm violet LED chip).