# Patent

## Title
ABOS:M-based phosphors and light sources containing these phosphors

## Abstract

This invention is related to efficient anorganic phosphors, which are based on an oxysulfide host lattice of the general formula ABOS:M. Furthermore, this invention is related to the use of these phosphors in various technical applications such as fluorescent lamps, colored light or white light emitting LEDs, scanning beam displays working with UV or purple laser as exciting source and other devices in order to convert especially UV or NUV radiation or short-wave visible light into an useful longer-wave visible radiation. This invention is also related to light sources and/or display applications that contain the inventive phosphor. An inventive phosphor shows the general formula ABOS:M, where A is at least one element selected from the group consisting of Ca, Mg, Sr, and Ba; B is at least one element selected from the group consisting of Zn and Mg; M is at least one first element selected from the group consisting of Mn2+, Cu2+, and Eu2+, Pb2+, Sb3+, Sn2+, Bi3+, Ce3+, Tb3+, and Pr3+; and additionally at least one second element selected from the group consisting of Mn2+, Cu2+, Cu+, Ag+, Pb2+, Sb3+, Sn2+, Bi3+, Eu2+, Ce3+, Tb3+, Pr3+ and La3+ as well as Li+, Na+, K+, and Rb+, wherein at least one of the second elements is different from every one of the first elements.

## Background
FIELD OF THE INVENTION
This invention is related to efficient anorganic phosphors, which are based on an oxysulfide host lattice of the general formula ABOS:M. Furthermore, this invention is related to the use of these phosphors in various technical applications such as fluorescent lamps, colored light or white-light-emitting LEDs, scanning beam displays working with UV or purple lasers as exciting sources and other devices in order to convert especially UV or NUV radiation or short-wave visible light into useful longer-wave visible radiation. This invention is also related to light sources and/or display applications that contain the inventive phosphor.
BACKGROUND
CaZnOS was described as the first alkaline earth zinc oxysulfide compound in 1977 by V. I. Yarygin, M. M. Shokarev, V. E. Mamaev, I. M. Kolganov, N. I. Kopylov: Izvestija Akademii Nauk SSSR, Metally 2 (1977) 104-7.
Furthermore, the preparation, structure and physical properties of CaZnOS were presented in several publications, e.g., in S. A. Petrova, V. P. Marevich, R. G. Zakharov, E. N. Selivanov, V. M. Chumarev, L. Yu. Udoeva: Doklady Chemistry, 393 (2003) p. 255-258 and T. Sambrook, C. F. Smura, S. J. Clarke, K. M. Ok, P. Shiv Halasyamani: Inorg. Chem. 46 (2007) p. 2571-2574. Additionally, the preparation and structure of BaZnOS were published by S. Broadley, Z. A. Gál, F. Corá, C. F. Smura, S. J. Clarke in Inorg. Chem. 44 (2005) p. 9092-9096. It has been shown that CaZnOS and BaZnOS crystallize in different structures whereas CaZnOS has a hexagonal symmetry with a space group of P63mc and BaZnOS an orthorhombic one with a space group of Cmcm.
A first BaZnOS-based phosphor activated by Cu was presented in Xia, Y., et al.: “Luminescence properties of Cu-activated BaZnOS phosphor” in Solid State Science, 2007, 9, 1074. Additionally, BaZnOS-based phosphors that are activated by Mn and Cu are disclosed in CN 101081979 A.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide novel band-emitting phosphors that show improved efficiency properties when excited by radiation in the ultraviolet or blue range and regarding a small width at half maximum.
This invention discloses phosphors having the general formula ABOS:M, where A is at least one element selected from the group consisting of Ca, Mg, Sr, and Ba; B is at least one element selected from the group consisting of Zn and Mg; and M is at least one first element selected from the group consisting of Mn2+, Cu2+, and Eu2+, Pb2+, Sb3+, Sn2+, Bi3+, Ce3+, Tb3+, and Pr3+. M additionally contains one or more second elements selected from the group consisting of Mn2+, Cu2+, Cu+, Ag+, Pb2+, Sb3+, Sn2+, Bi3+, Eu2+, Ce3+, Tb3+, Pr3+ and La3+ as well as Li+, Na+, and Rb+. At least one of the second elements is different from every one of the first elements; i.e., M consists of at least two different elements. The single first element or the multiple first elements act as activators. The single second element or the multiple second elements act as coactivators or as sensitizers.
If trivalent activators Sb3+, Bi3+, Ce3+, Tb3+, and/or Pr3+ are used, charge equalization is possible by addition of monovalent cations, such as alkali metal ions Li+, Na+, Rb+. If more than one activator is used one of the activators can serve as a coactivator or sensitizer.
The concentrations of these activators, co-activators and/or sensitizers are preferably adjusted in the range from zero up to 50 atomic percent.
The inventive phosphors show excitation bands in the range of 200 nm to 550 nm. They can also be excited by cathode (CR) radiation.
Preferably, the phosphors of this invention emit a longer-wave radiation in the visible range of 400 nm to 780 nm depending on activator ion and activator concentration.
In a preferred embodiment, one of the first elements of M is Mn2+; i.e., the phosphor is activated by Mn2+. The single second element or the multiple second elements of M are selected from the group consisting of Cu2+, Pb2+, Sn2+, Eu2+, Bi3+, Ce3+, Tb3+, La3+, and Pr3+ as well as Li+, Na+, K+, and Rb+. These elements can serve as coactivators or sensitizers. If trivalent activators are used, charge equalization is possible by monovalent cations, such as Li+, Na+, K+, Rb+. The inventive Mn2+-activated ABOS phosphors show an efficient narrowband orange to red emission. Due to the sensitizer or coactivator ions, further weaker emission bands or lines can also occur. The Mn2+-activated ABOS phosphors can be excited by UV radiation or short-wave visible light. The advantage of these phosphors is that their excitability can be modified by the choice of the sensitizer and/or coactivator ions so that the application fields of phosphor can be expanded. The function of sensitizer ions consists in (1) the effective absorption of such an excitation radiation which can not be applied for Mn2+ ions as a luminescence center alone and in (2) an efficient energy transfer of the absorbed energy to the Mn2+ ions leading to an intensive Mn2+ emission. Therefore, the field of application can be expanded, especially for applications where an NUV or longer-wave radiation is used as excitation source such as white-light emitting LEDs.
In preferred embodiments of the inventive phosphor, Mn2+ is the only first element of M and the phosphor shows one of the following general formulas:
CaZnOS:M;
CaZnOS:M, wherein the second element of M is Pb2+;
BaZnOS:M;
BaZnOS:M, wherein the second elements of M are La3+ and Li+;
BaZnOS:M, wherein the second elements of M are Bi3+ and Li+;
BaZnOS:M, wherein the second element of M is Pb2+.
In a special embodiment, the inventive phosphor is based on BaZnOS, whereas Ba can be partially replaced by Mg, Ca and/or Sr, and whereas Zn can be partially replaced by Mg. The phosphor is activated by Mn2+ and one or more elements selected from the main group elements Pb2+, Sn2+, Bi3+, Sb3+, Li+, Na+, K+ and Rb+; from the rare earth elements such as Eu2+, Ce3+, Tb3+, Pr3+, and La3+; and from the group of transition metals Ag+, Cu+ and Cu2+. The other activators, besides Mn2+, serve as coactivators or sensitizers. If trivalent activators are used, charge equalization is possible by monovalent cations, such as alkali metal ions Li+, Na+, K+, Rb+. Mn2+-activated BaZnOS phosphors show a red emission band in the wavelength range between 550 nm and 780 nm peaking at 620 nm to 650 nm. Due to sensitizer or coactivator ions, further weaker emission bands or lines can also occur. The maximum of excitation of the inventive sensitized Mn2+-activated BaZnOS is red-shifted compared to that of non-sensitized BaZnOS. Therefore, it is possible to use UV radiation of 350 nm or longer wavelengths to excite the phosphor. As a consequence, the inventive phosphor can be applied e.g., in light applications such as high-pressure mercury discharge lamps or white-light emitting LEDs.
In a further special embodiment, the inventive phosphor is based on CaZnOS, whereas Ca can be partially replaced by Mg, Sr, and/or Ba, and whereas Zn can be partially replaced by Mg.
In contrast to the alkaline earth oxysulfides like Sr2OS or Ca2OS and alkaline earth metal sulfides, CaZnOS is chemically stable in moist air. This phosphor can be activated by one or more first elements of M selected from the group of transition metals Mn2+, Cu2+, Cu+, and Ag+ main group elements Pb2+, Sb3+, Sn2+, Bi3+, Li+, Na+, K+, and Rb+; and rare earth elements Eu2+, Ce3+, Tb3+, Pr3+, and La3+. If more than one activator is used, one of the activators can serve as coactivator or sensitizer. If trivalent activators are used, charge equalization is possible by monovalent cations, such as alkali metal ions Li+, Na+, K+, Rb+. The inventive phosphors according to this embodiment can be excited by UV radiation or short-wave visible light and show longer-wave emission bands in the visible range of 400 nm to 780 nm depending on activator ion and activator concentration, e.g., Pb2+ or Bi3+-activated CaZnOS phosphors show a blue emission band in the wavelength range 350 nm to 550 nm with peak centers at 405 nm to 425 nm and 460 nm to 480 nm, respectively, when excited by UV radiation.
Due to its non-centrosymmetric structure, CaZnOS is especially suitable for an Mn-based luminescence. Mn2+-activated CaZnOS phosphors can not only be excited by UV-B radiation, but also have strong excitation bands in the wavelength range 380 nm to 550 nm. These phosphors show an orange-red emission band in the wavelength range 550 nm to 780 nm peaking at 610 nm to 620 nm.
Preferably, the Mn2+-activated CaZnOS phosphors are coactivated and/or sensitized by Cu2+, Cu+, Ag+, Pb2+, Sn2+, Bi3+, Ce3+, Tb3+, La3+ and Pr3+. By that, the excitability of the phosphor can be modified and the efficiency can be increased. Due to the function of the sensitizer ion, it is possible to apply an excitation radiation which is not applicable for the Mn2+ ion alone, but which can effectively be absorbed by the sensitizer ion. After an efficient transfer of the absorbed energy from the sensitizer ion to the Mn2+ luminescent center, an intense Mn2+ based emission is shown as it is observed for, e.g., CaZnOS:Mn2+, Pb2+, i.e., M consists of Mn2+ and Pb2+. The advantage of these combinations of activators consists in a considerable enhancement of the excitability of the inventive phosphors in the NUV range between 300 nm and 400 nm.
Due to the described luminescence characteristics, the phosphors according to the present invention can be used as a radiation converter for the transformation of cathode, UV, violet or blue radiation into a longer-wave visible light that will be emitted by the phosphor preferably in the blue to red spectral region.
As appropriate technical devices, cathode ray tubes (CRT), special laser-based large screen displays, fluorescent lamps, colored light or white emitting LED's, and also, for example, photovoltaic cells or greenhouse foils or glasses can be regarded.
As excitation sources for the inventive phosphors, electron generators, high or low-pressure discharge plasmas, UV or blue emitting organic or inorganic light emitting diodes (LED) or appropriate lasers or laser diodes, or, in addition, inorganic thin or thick electroluminescent screens are used.
The inventive phosphor can be used as single component in a relevant light emitting element or in combination with other red, yellow, green, and/or blue-emitting phosphors in order to improve the performance of the respective application. The latter meets, for example, the improvement of the color rendering indices (CRI) of fluorescent lamps and white emitting LED's.
An inventive light source comprises a first phosphor according to the invention and a second phosphor that emits red, yellow, green, and/or blue light.
The inventive phosphor can be prepared by careful mixing of alkaline earth metal oxide and ZnS as well as one or more activator or coactivator compounds and subsequent firing of the mix at 900-1200° C. (preferably 1000-1100° C.) in an inert atmosphere (nitrogen, noble gas) or in a reduced atmosphere (H2/N2) for 4-48 h.

    
    
        Instead of alkaline earth metal oxide, another alkaline earth metal oxide precursor such as the corresponding acetate, carbonate, nitrate, oxalate, or sulfate can be used.
        ZnS may be partially replaced by MgS.
        MnO, manganese oxide precursors such as manganese(II) carbonate, manganese nitrate, manganese sulfate, as well as other manganese compounds such as MnS or further manganese(II) salts can be used as activator compounds.
        The oxides of copper, silver, lead, tin, bismuth, cerium, europium, lanthanum, praseodym and terbium as well as their precursors such as the corresponding acetates, carbonates, nitrates, oxalates, or sulfates, or further salts of the above mentioned metals can be used as activator compounds.
        The oxides of lithium, sodium, potassium or rubidium as well as their precursors such as the corresponding acetates, carbonates, nitrates, oxalates, or sulfates, or further salts of the above-mentioned metals can be used as coactivator compounds to keep the charge neutrality when trivalent activators are used.
        Melting agents, such as alkali metal halide, alkaline earth metal halide and ammonium halide can be used in order to improve the crystal habit and in order to control the grain size.
    
    


In another embodiment, the phosphor is made from an alkaline earth metal sulfide and ZnO as well as one or more activator compounds according to the above procedure. ZnO can be partially replaced by MgO. A third method of preparing the inventive phosphor is based on the reaction of alkaline earth metal oxide or a corresponding precursor and ZnO as well as one of the above-mentioned activator compounds with sulfur, soda and an appropriate fluxing agent such as alkali phosphate at a temperature between 900° C. and 1200° C. in air. ZnO can be partially replaced by MgO.
The grain size of the inventive phosphor may vary in a large range. An average grain size of the phosphor can be a few nanometers. However, the grain size can be adjusted to particle sizes up to 30 μm.
In the context of this invention, a further phosphor was found that is currently not claimed in this patent application. This phosphor shows the general formula ABOS:M, where A is at least one element selected from the group consisting of Ca, Mg, Sr, and Ba; B is at least one element selected from the group consisting of Zn and Mg; and M is at least one first element selected from the group consisting of Mn2+, Cu2+, and Eu2+, Pb2+, Sb3+, Sn2+, Bi3+, Ce3+, Tb3+ and Pr3+; and additionally none or at least one second element selected from the group consisting of Mn2+, Cu2+, Cu+, Ag+, Pb2+, Sb3+, Sn2+, Bi3+, Eu2+, Ce3+, Tb3+, Pr3+ and La3+ as well as Li+, Na+, K+, and Rb+. In one of the preferred embodiments, M contains none of the second elements. In another preferred embodiment, the phosphor shows the general formula CaZnOS:M, whereas Ca can be partially replaced by Mg, Sr, and/or Ba; whereas Zn can be partially replaced by Mg; and whereas M contains none of the second elements. In a further preferred embodiment, the phosphor shows the general formula CaZnOS:Mn2+, whereas Ca can be partially replaced by Mg, Sr, and/or Ba; whereas Zn can be partially replaced by Mg. Moreover, this phosphor can be implemented analogously to the abovementioned embodiments of the inventive phosphor.



DETAILED DESCRIPTION
The foregoing features and advantages of the present invention will become better understood and more readily appreciated by reference to the following detailed description of the preferred embodiments of invention taken in conjunction with the accompanying drawings, wherein:
FIG. 1: Diffuse reflection spectra of CaZnOS (comparative sample 1) and CaZnOS:Mn2+ sample 1 and 2, respectively;
FIG. 2: Excitation and Emission spectra of CaZnOS:Mn2+ sample 1;
FIG. 3: Emission spectra of CaZnOS:Mn2+ (sample 3) and CaZnOS:Mn2+, Pb2+ (sample 4) under 365 nm excitation; and
FIG. 4: Emission spectra of BaZnOS:Mn2+ comparative example 2, BaZnOS:Mn2+, Bi3+, Li+ (sample 5) and BaZnOS:Mn2+, La3+, Li+ (sample 6) under 365 nm excitation.



In the following, preparation and photoluminescence properties of some preferred examples of inventive Mn2+-activated CaZnOS phosphor are presented. The polycrystalline CaZn1-xMnxOS (0≦x≦0.2) powders were prepared by a solid state reaction at high temperature. The appropriate amounts of CaCO3, ZnS and MnCO3 powders were weighed out and subsequently mixed and ground together. In detail the following were used for 0.015 mol phosphor:












Comparative sample 1
Sample 1
Sample 2







CaZnOS
CaZnOS:Mn2+ (5%)
CaZnOS:Mn2+ (20%)


1.5013 g CaCO3
1.5013 g CaCO3
1.5013 g CaCO3


1.4616 g ZnS
1.3885 g ZnS
1.1693 g ZnS



0.0862 g MnCO3
0.3448 g MnCO3









The powder mixtures were then transferred into molybdenum crucibles. Subsequently, those powder mixtures were fired at 1000° C. for 48 h under flowing N2 atmosphere. After firing, the samples were gradually cooled down to room temperature in the furnace.
FIG. 1 shows the diffuse reflection spectra of undoped comparative and the Mn2+-doped CaZnOS samples. Both undoped and Mn2+-doped samples show a strong drop in reflection in the UV range below 300 nm, corresponding to the absorption of the CaZnOS host lattice. Additionally, several narrow strong absorption bands located at 396 nm, 438 nm and 490 nm can be seen from the reflection spectra of higher Mn2+ concentration samples 1 and 2, which can be attributed to the absorption by Mn2+ ions due to the absence of them in undoped CaZnOS (comparative sample 1). The intensities of these increase for higher Mn2+ concentration. As a consequence of the strong absorption of the Mn2+ ions in the visible range, around 350-550 nm, CaZnOS:Mn2+ phosphors show white to pink color varying with the Mn2+ concentration. In fact, the absorption behavior of CaZnOS:Mn2+ phosphor is unusual and contrary to the expectation because weak absorption in the visible range is expected due to strictly forbidden d-d transitions of Mn2+ ions.
FIG. 2 shows the excitation and emission spectra of CaZnOS:Mn2+ (5%) phosphor (sample 1).
The emission spectrum of CaZnOS:Mn2+ phosphor shows a narrow symmetric emission band in the wavelength range of 550 nm to 700 nm with a peak center at 614 nm irrespective of the excitation wavelength. The half-width for this single narrow emission band is about 50 nm.
The excitation spectrum of CaZnOS:Mn2+ phosphor extends for a broad range of wavelengths (230 nm to 550 nm) and is consistent with the diffuse reflectance spectra in FIG. 1. Definitely, the short strong excitation bands below 350 nm originate from host lattice excitation as can be concluded from the comparison with the reflection spectrum. The appearance of the host lattice excitation bands in the excitation spectrum of Mn2+ indicates that there exists efficient energy transfer from the host lattice of CaZnOS to Mn2+ ions. The remaining excitation bands in the wavelength range of 350 nm to 550 nm can be assigned to the transitions of Mn2+ ions. The shape and position of the host lattice excitation bands and Mn2+ excitation bands are almost independent of the Mn2+ doping concentrations except for a minor redshift in the peak center of host lattice excitation bands with increasing Mn2+ concentration. In addition, the ratio between the intensities of the excitation bands increases with increasing Mn2+ concentration. Finally, a typical band emission of Mn2+ in a CaZnOS host lattice can be realized in both ways—exciting the Mn2+ ion directly in its own excitation levels or exciting the host lattice with following efficient energy transfer from the host lattice to the Mn2+ ion—making the phosphor suitable for UV as well as white-light emitting LED applications. It should be mentioned that as for the compounds of CaZnOS and BaZnOS, Mn2+ shows a different luminescence property in these two compounds, which can be ascribed to the different crystal structure and different coordination environment for Mn ion in these two compounds. Especially, the high absorption and strong excitation bands of CaZnOS:Mn phosphor in the wavelength range of 350 nm to 550 nm are very favorable properties for applications as LED conversion phosphors.
An important feature of the inventive phosphor is the addition of further activators and/or sensitizers to Mn2+-activated CaZnOS or BaZnOS phosphors. Such sensitized phosphors were prepared as described in the following: Appropriate amounts of CaCO3 or BaC2O4, ZnS, MnS, PbCO3, Bi2O3, La2O3 and Li2CO3 powders were weighed out and subsequently mixed and ground together. In detail the following were used for 0.25 mol phosphor:


















Comparative


Sample 3
Sample 4
Sample 5
Sample 6
sample 2







CaZnOS:Mn2+
CaZnOS:Mn2+,
BaZnOS:Mn2+,
BaZnOS:Mn2+,
BaZnOS:Mn2+


(3%)
Pb2+ (3%/5%)
Bi3+, Li+ (1%/0.5%)
La3+, Li+ (1%/0.5%)
(1%)
















25.022
g CaCO3
23.771
g CaCO3
55.774
g BaC2O4
55.774
g BaC2O4
56.337
g BaC2O4


23.629
g ZnS
23.629
g ZnS
24.116
g ZnS
24.116
g ZnS
24.116
g ZnS


0.652
g MnS
0.652
g MnS
0.217
g MnS
0.217
g MnS
0.217
g MnS




3.340
g PbCO3
0.291
g Bi2O3
0.204
g La2O3






0.046
g Li2CO3
0.046
g Li2CO3









The powder mixtures were then transferred into alumina crucibles. Subsequently, those powder mixtures were fired at 920-1050° C. for 8 h under flowing N2 atmosphere. After firing, the samples were gradually cooled down to room temperature in the furnace.
Unfortunately, MZnOS:Mn2+ phosphors with M=Ca, Ba show a lack in excitibiliy in the range 320 nm to 430 nm. In the case of CaZnOS, this problem can be overcome by using Pb2+ ions as a further activator that also acts as a sensitizer.
FIG. 3 shows the emission spectra of CaZnOS:Mn2+ phosphors and CaZnOS:Mn2+, Pb2+ phosphors at 365 nm excitation, in comparison. CaZnOS phosphors doped with Pb2+ ions only show a blue emission band in the wavelength range 350 nm to 550 nm with peak center at 405 nm to 425 nm, respectively, when excited by UV radiation at 330 nm to 380 nm. When the phosphor is co-doped with Mn2+ ions, an efficient energy transfer from the excited Pb2+ ions to the Mn2+ ions takes place and an intensive red Mn2+ emission can be observed.
The excitability of BaZnOS:Mn2+ phosphors in the NUV range can be especially increased by co-doping of Bi3+, La3+ or Pb2+ as it is demonstrated for Bi3+ and La3+ in FIG. 4. For keeping the charge neutrality of the compound monovalent ions like Li+, Na+, K+ or Rb+ can be added when trivalent activators are used.
Bi3+ and Pb2+-activated BaZnOS phosphors show a blue emission band in the wavelength range 400 nm to 550 nm with peak center at 470 nm to 495 nm and 455 nm to 460 nm, respectively, when excited by NUV radiation at 365 nm. BaZnOS phosphors doped with Mn2+ and Bi3+ or La3+ and Li+ show a narrow symmetric emission band in the wavelength range of 550 nm to 700 nm with peak center at about 630 nm to 635 nm when excited in the NUV range. This emission band can be ascribed to the manganese luminescence and is the consequence of an efficient energy transfer from the excited Bi3+ or La3+ ions to the Mn2+ ions.
However, the composition of the inventive phosphor is not limited to the examples described.

## Claims

1. A phosphor having the general formula:
ABOS:M, where
A is at least one element selected from the group consisting of Ca, Mg, and Sr;
B is at least one element selected from the group consisting of Zn and Mg; and
M is at least one element selected from the group consisting of Mn2+, Pb2+, Sb3+, and Bi3+; and wherein M optionally further comprises at least one element selected from the group consisting of Pb2+, Bi3+, Li+, Na+, K+, and Rb+.

2. The phosphor according to claim 1, having the general formula:
CaZnOS:M, where
Ca is partially replaced by Mg, and/or Sr; and/or
Zn is partially replaced by Mg.

3. The phosphor according to claim 2, wherein M contains at least one element selected from the group consisting of Sb3+ and Bi3+ and at least one element selected from the group consisting of Li+, Na+, K+, and Rb+.

4. The phosphor according to claim 2, wherein M contains Mn2+ and additionally none or at least one element selected from the group consisting of Pb2+ and Bi3+ as well as Li+, Na+, K+, and Rb+.

5. The phosphor according to claim 1, wherein M contains at least one element selected from the group consisting of Sb3+ and Bi3+ and at least one element selected from the group consisting of Li+, Na+, K+, and Rb+.

6. The phosphor according to claim 5, wherein M contains Mn2+ and additionally none or at least one element selected from the group consisting of Pb2+ and Bi3+ as well as Li+, Na+, K+, and Rb+.

7. The phosphor according to claim 1, wherein M contains Mn2+ and optionally further consists of at least one element selected from the group consisting of Pb2+, Bi3+, Li+, Na+, K+, and Rb+.

8. The phosphor according to claim 7, wherein Mn2+ is the only first element of M and the phosphor shows one of the following general formulas:
CaZnOS:M;
CaZnOS:M, wherein the second element of M is Pb2+.

9. The phosphor according to claim 1, wherein M is adjusted in the range from zero up to 50 atomic percent.

10. The phosphor according to claim 1, wherein the phosphor shows emission bands in the visible range of 400-780 nm.

11. The phosphor according to claim 1, wherein the phosphor shows excitation bands in the range of 200-550 nm.

12. The phosphor according to claim 1, wherein the phosphor shows emission bands with a small width at half-maximum.

13. A light source comprising a light emitting element that emits a first radiation and a phosphor according to claim 1, wherein the phosphor is used as a radiation converter for the transformation of at least a part of said first radiation emitted by the light emitting element.

14. The light source according to claim 13, wherein the first radiation emitted by said light emitting element comprises cathode or X-rays, UV, violet or blue radiation, which is transformed partly or in full into a longer-wave visible light that will be emitted by the phosphor preferably in a blue to red spectral region.

15. The light source according to claim 14, wherein the light emitting element is an electron or X-ray generator, a high or low-pressure discharge plasma, a UV or blue emitting organic or inorganic light emitting diode (LED) or laser or laser diode, or in addition, an inorganic thin or thick electroluminescent screen.

16. The light source according to claim 14 further comprising at least a second phosphor that emits red, yellow, green, and/or blue light.

17. The light source according to claim 13, wherein the light emitting element is an electron or X-ray generator, a high or low-pressure discharge plasma, a UV or blue emitting organic or inorganic light emitting diode (LED) or laser or laser diode, or an inorganic thin or thick electro-luminescent screen.

18. The light source according to claim 15 further comprising at least a second phosphor that emits red, yellow, green, and/or blue light.

19. The light source according to claim 18 wherein the light source is embodied in a fluorescent lamp or white emitting LED with an improved CRI.

20. The light source according to claim 15, wherein the light source is embodied in a CRT, a laser-based display, a fluorescent lamp, a colored light or white emitting LED, a PV cell, or a greenhouse foil or glass.