# Patent

## Title
Luminescent material

## Abstract

A luminescent material is disclosed. The luminescent material may include a first compound having a host lattice comprising first ions and oxygen. A first portion of the first ions may be substituted by copper ions. In one embodiment, the host lattice may include silicon, the copper ions may be divalent copper ions and the first compound may have an Olivine crystal structure, β-K0.2SO4 crystal structure, a trigonal Glaserite (K3Na(SO4)2) or monoclinic Merwinite crystal structure, a tetragonal Ackermanite crystal structure, a tetragonal crystal structure or an orthorhombic crystal structure. In another embodiment, the copper ions do not act as luminescent ions upon excitation with the ultraviolet or visible light.

## Background
CROSS REFERENCE TO RELATED APPLICATIONS
The present application is a continuation of U.S. patent application Ser. No. 11/948,813, filed on Nov. 30, 2007, which is a continuation-in-part of U.S. patent application Ser. No. 11/024,722, filed on Dec. 30, 2004, and claims priority from and the benefit of Korean Patent Application No. 10-2004-0042397, filed on Jun. 10, 2004, which is hereby incorporated by reference for all purposes as if fully set forth herein.


BACKGROUND OF THE INVENTION
1. Field of the Invention
Embodiments of the present invention relate generally to fluorescent materials containing rare earth elements and, more particularly, to such luminescent materials for exciting ultraviolet as well as visible light containing lead- and/or copper-containing compounds.
2. Description of the Related Art
Lead and copper activated materials are known for short wave excitation, e.g. from a low pressure mercury lamp, such as barium disilicate activated by lead (Keith H. Butler, The Pennsylvania State University Press, 1980, S 175, orthosilicate activated by lead (Keith H. Butler, The Pennsylvania State University Press, 1980, S. 181), akermanites activated by lead, or Ca-metasilicate activated by Pb2+.
Generally, the maxima of the emission bands of such lead activated phosphors are located between 290 nm and 370 nm at 254 nm excitation. Bariumdisilicate activated by lead is an U.V. emitting phosphor which currently is used in sun parlor lamps.
Lead has in the ground state 1S0 two outer electrons. The electron configuration of the ground state is d10s2, so that the lowest excited state has d10sp configuration. The excited sp configuration has four levels, 3P0, 3P1, 3P2 and 1P1, which can be achieved between 165.57 nm (3P0) and 104.88 nm (1P1) in the free ion. Transitions between 1S0 and 1P1 excited level are allowed by all selection rules. While transitions between 1S0 and 3P0 are only allowed with the lowest symmetry, transitions between 1S0 and 3P1 as well as 3P2 are allowed only under certain conditions. However, excitation between 180 and 370 nm has the same emission. Excitation with wavelength longer than 370 nm is not possible.
Otherwise, luminescent materials are known having lead as a host lattice component. Molybdate phosphors containing MoO42− centers are described in Bernhardt, H. J., Phys. Stat. Sol. (a), 91, 643, 1985. PbMoO4 shows at room temperature red emission with an emission maximum at 620 nm under photoexcitation at 360 nm.
However, such emission is not caused by lead itself. In molybdates the luminescence properties are not caused by the metal ion M2+ (M2+MoO4 where M2+=Ca, Sr, Cd, Zn, Ba, Pb etc). Here, defect centers of MoO42− ions coupled to O2−-ion vacancies seem to be the reason. Nevertheless, the Pb2+-ion influences the preferred emission properties because it stabilizes the host lattice.
As a familiar example, tungstates (Ca,Pb)WO4 as mixed crystals have a strong green emission with high quantum output of 75% (Blasse, G, Radiationless processes in luminescent materials, in Radiationless Processes, DiBartolo, B., Ed. Plenum Press, New York, 1980, 287). Under 250 nm excitation PbWO4 shows blue emission and under 313 nm excitation PbWO4 has an orange emission band, which can be caused by Schottky defects or by impurity ions (Phosphor Handbook, edited under the Auspice of Phosphor Research Society, CRC Press New York, 1998, S 205).
Copper was used as a monovalent activator in orthophosphates (Wanmaker, W. L. and Bakker, C., J. Electrochem. Soc., 106, 1027, 1959) with an emission maximum at 490 nm. The ground state of monovalent copper is a filled shell 3d10. That is the level 1S0. After exciting the lowest excited configuration is 3d94s. This configuration has two terms, 3D and 1D. The next higher configuration, 3d94p, gives 6 terms 3P°, 3F°, 3D°, 1F°, 1D° and 1P°. The transitions between the ground state 1S0 and the 1D or 3D are forbidden by parity or spin, respectively. In copper ions, the excitation to the crystal field levels of 4p terms are allowed. Emission will be got either by a direct return from the crystal field odd state to the ground state or by a combination of transitions first from the odd state to a crystal field level and after that a second transition from these 3D or 1D state of the 3d94s configuration to the ground state.
The ground state of bivalent copper has 3d9-configuration. That is the level 2D5/2. In the bivalent copper, one of the d-electrons can be excited to the 4s or 4p orbital. The lowest exciting configuration is the 3d84s with two quartet terms 4F, 4P and four doublet terms, 2F, 2D, 2P and 2G without emission caused by forbidden transitions. The higher exciting configuration is the 3d84p-configuration with four terms 4D°, 4G°, 4F°, and 4P°, where emission can occur.
Copper activated or co-activated sulphide-phosphors are well known and they are commercial used for cathode ray tubes. The green-emitting ZnS:Cu, Al (wherein, the copper is used as activator and Al is used as co-activator) is very important in CRT applications.
In zinc-sulphide phosphors, the luminescent materials can be classified into five kinds, depending on the relative ratio of the concentration of activators and co-activators (van Gool, W., Philips Res. Rept. Suppl., 3, 1, 1961). Here, the luminescent centers are formed from deep donors or deep acceptors, or by their association at the nearest-neighbor sites (Phosphor Handbook, edited under the Auspice of Phosphor Research Society, CRC Press New York, 1998, S. 238).
Orthophosphates activated by copper (Wanmaker, W. L., and Spier, H. L., JECS 109 (1962), 109), and pyrophosphates, alumosilicates, silicates, and tripolyphosphates all activated by copper are described in “Keith H. Butler, The Pennsylvania State University Press, 1980, S. 281”. However, such phosphors can only be used for a short wave U.V. excitation. Because of their unstable chemical properties and their temperature behavior, they cannot be used in fluorescent lamps.
It has been observed that conventional luminescent materials are generally unstable in water, air humidity, water steam and polar solvents.
SUMMARY OF THE INVENTION
One embodiment exemplarily described herein can be generally characterized as a luminescent material for a light emitting diode (LED) that includes a first compound including a host lattice and a luminescent ion within the host lattice. The host lattice may include first ions and oxygen. A first portion of the first ions may be substituted by divalent copper ions. The first compound may emit light upon excitation with ultraviolet light or visible light emitted by the LED. The first compound may have an Olivine crystal structure, a β-K0.2SO4 crystal structure, a trigonal Glaserite (K3Na(SO4)2) or monoclinic Merwinite crystal structure, a tetragonal Ackermanite crystal structure, a tetragonal crystal structure or an orthorhombic crystal structure.
According to another embodiment, the luminescent ion includes at least one of Bi, Sn, Sb, Sc, Y, La, In, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. According to another embodiment, the first compound includes Ge. According to another embodiment, the luminescent material further includes at least one second compound selected from the group consisting of an aluminate, a silicate, an antimonite, a germinate, a germinate-silicate and a phosphate. According to another embodiment, the luminescent material emits white light upon excitation with ultraviolet light or visible light.
Another embodiment exemplarily described herein can be generally characterized as a luminescent material for a light emitting diode (LED) that includes a first compound including a host lattice and a luminescent ion within the host lattice. The host lattice may include first ions and oxygen. A first portion of the first ions may be substituted by copper ions. The first compound may emit light upon excitation with ultraviolet light or visible light emitted by the LED. However, the copper ions do not act as luminescent ions upon excitation with the ultraviolet light or visible light. An additional object of the present invention is to provide lead and/or copper doped luminescent materials, which give high color temperature range about 2,000K to 8,000K or 10,000K and CRI over 90 in LED.


DETAILED DESCRIPTION
According to embodiments exemplarily described herein, a luminescent material may include one or more lead- and/or copper-containing chemical compounds. The luminescent material may be excited by UV and/or visible (e.g., blue) light. In some embodiments, the lead- and/or copper-containing chemical compounds may be generally characterized as including a host lattice having anions and cations. In some embodiments, at least a portion of the cations are divalent cations. In some embodiments, the divalent cations include alkaline earth ions. In some embodiments, at least a portion of the divalent cations of the host lattice are substituted by divalent lead and/or divalent copper ions.
As mentioned above, conventional luminescent materials are generally unstable in water, air humidity, water steam and polar solvents. However, due to a higher covalency and a lower basicity, the substitutionally-incorporated divalent lead and/or divalent copper ions in the host lattice of the chemical compound yields luminescent materials having improved resistance against water, air humidity and polar solvents.
The divalent lead and/or divalent copper ions within the host lattice do not act as activators (also referred to herein as “luminescent ions”) and, therefore do not luminance. Rather, it has been found that these ions tend to influence the crystal field splitting as well as the covalency of the chemical compound. As a result, the substitutional incorporation of divalent lead and/or copper ions within the host lattice tends to influence luminescent-optical properties of the chemical compounds so as to improve luminescent intensity and desirably shift the emission maxima, color points, and shape of emission spectra.
It has been found that phosphors having chemical compounds that contain substitutionally-incorporated divalent lead and/or divalent copper ions show improved emission intensities as compared with phosphors having chemical compounds that do not contain substitutionally-incorporated divalent lead and/or divalent copper ions.
In addition, it has been found that phosphors having chemical compounds that contain substitutionally-incorporated divalent lead and/or divalent copper ions tend to show improved luminescent properties for excitation wavelength higher than about 360 nm. At excitation wavelengths higher than about 360 nm, the divalent lead and/or divalent copper ions do not exhibit their own radiation transfers due to the energy levels of their electron configuration, so that any kind of exciting radiation cannot be lost. Furthermore, by substitutionally incorporating divalent lead and/or divalent copper ions, the emission wavelength can be shifted to higher or lower energies as desired.
Lead ions having an ionic radius of 119 μm can substitute the alkaline earth ions Ca having an ionic radius of 100 μm and Sr having an ionic radius of 118 μm very easily. The electro negativity of lead with 1.55 is much higher than that of Ca (1.04) and Sr (0.99). The preparation of substances containing lead is complicated due to the possibility of an oxidation of these ions in reducing atmospheres. For the preparation of lead-containing compounds, which need reducing atmosphere, special preparation processes are necessary.
The influence of substitutionally-incorporated divalent lead ions in the crystal field on the shifting of emission characteristics depends upon the substituted ions. When divalent lead ions substitute Sr or Ba in Eu-activated aluminates and/or silicates, the emission maximum tends to be shifted to longer wavelengths due to smaller ionic radii of Pb as compared with the ionic radii of Ba and Sr. That leads to a stronger crystal field surrounding the activator ion.
A similar effect shows the substitution of divalent copper ions for alkaline earth ions. Here, an additional influence is effective. Due to the higher ionic potential of copper as a quotient of ionic charge and ionic radius compared to the bigger alkaline earth ions, the copper ions can attract the neighboring oxygen ions stronger than the alkaline earth ions. So the substitution of the bigger alkaline earth ions Ca, Sr and Ba by copper leads to a stronger crystal field in the surrounding of the activator ions, too. Thus, the shape of emission bands can be influenced, the shifting of the emission peak to longer wavelength is connected in a broadening of the emission curves for band emission. In addition, it should be possible to increase the intensity of emission by substitution of ions copper and lead. Generally, the shifting of emission peaks to longer or shorter wavelengths are desirable in the field of LED lighting. Here, it is necessary to realize a fine tuning to get a special wavelength for desired color points as well as for better brightness of optical devices. By using cations, copper and lead, such a fine tuning should be possible.
As described above, the luminescent material may include one or more chemical compounds such as, for example, aluminates, silicates, antimonates, germinates, germinate-silicates, and/or phosphates. Exemplary embodiments of these luminescent materials are described in greater detail below.
EXAMPLE 1
Luminescent materials for ultraviolet light or visible light excitation comprise lead- and/or copper-containing aluminates exemplarily characterized according to the formula as follows:

a(M′O).b(M′′2O).c(M′′X).dAl2O3.e(M′′′O).f(M′′′′2O3).g(M′′′′′oOp).h(M′′′′′′xOy)  (1)

wherein M′ may be Pb, Cu, and/or any combination thereof; M′′ may be one or more monovalent elements, for example, Li, Na, K, Rb, Cs, Au, Ag, and/or any combination thereof; M′′′ may be one or more divalent elements, for example, Be, Mg, Ca, Sr, Ba, Zn, Cd, Mn, and/or any combination thereof; M′′′′ may be one or more trivalent elements, for example, Sc, B, Ga, In, and/or any combination thereof; M′′′′′ may be Si, Ge, Ti, Zr, Mn, V, Nb, Ta, W, Mo, and/or any combination thereof; M′′′′′′ may be Bi, Sn, Sb, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and/or any combination thereof; X may be F, Cl, Br, I, and/or any combination thereof; 0<a≦2; 0≦b≦2; 0≦c≦2; 0<d≦8; 0<e≦4; 0≦f≦3; 0≦g≦8; 0<h≦2; 1≦o≦2; 1≦p≦5; 1≦x≦2; and 1≦y≦5.

a(M′O).b(M′′2O).c(M′′X).4−a−b−c(M′′′O).7(Al2O3).d(B2O3).e(Ga2O3).f(SiO2).g(GeO2).h(M′′′′xOy)  (2)

wherein M′ may be Pb, Cu, and/or any combination thereof; M′′ may be one or more monovalent elements, for example, Li, Na, K, Rb, Cs, Au, Ag, and/or any combination thereof; M′′′ may be one or more divalent elements, for example, Be, Mg, Ca, Sr, Ba, Zn, Cd, Mn, and/or any combination thereof; M′′′′ may be Bi, Sn, Sb, Sc, Y, La, In, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and any combination thereof; X may be F, Cl, Br, I, and any combination thereof; 0<a≦4; 0≦b≦2; 0≦c≦2; 0≦d≦1; 0≦e≦1; 0≦f≦1; 0≦g≦1; 0<h≦2; 1≦x≦2; and 1≦y≦5.
The preparation of copper- as well as lead-containing luminescent materials may be a basic solid state reaction. Pure starting materials without any impurities, e.g. iron, may be used. Any starting material which may transfer into oxides via a heating process may be used to form oxygen dominated phosphors.
Examples of Preparation:
Preparation of the Luminescent Material Having Formula (3)

Cu0.02Sr3.98Al14O25:Eu  (3)

Starting materials: CuO, SrCO3, Al(OH)3, Eu2O3, and/or any combination thereof.
The starting materials in the form of oxides, hydroxides, and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux, e.g., H3BO3. The mixture may be fired in an alumina crucible in a first step at about 1,200° C. for about one hour. After milling the pre-fired materials a second firing step at about 1,450° C. in a reduced atmosphere for about 4 hours may be followed. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum of about 494 nm.







TABLE 1







copper containing Eu2+-activated aluminate compared with Eu2+-


activated aluminate without copper at about 400 nm excitation wavelength











Compound 



Compound containing copper
without copper



Cu0.02Sr3.98Al14O25: Eu
Sr4Al14O25: Eu













Luminous density (%)
103.1
100


Wavelength (nm)
494
493









Preparation of the Luminescent Material Having Formula (4)

Pb0.05Sr3.95Al14O25:Eu  (4)

Starting materials: PbO, SrCO3, Al2O3, Eu2O3, and/or any combination thereof.
The starting materials in form of very pure oxides, carbonates, or other components which may decompose thermically into oxides, may be mixed in stoichiometric proportion together with small amounts of flux, for example, H3BO3. The mixture may be fired in an alumina crucible at about 1,200° C. for about one hour in the air. After milling the pre-fired materials a second firing step at about 1,450° C. in air for about 2 hours and in a reduced atmosphere for about 2 hours may be followed. Then the material may be milled, washed, dried, and sieved. The resulting luminescent material may have an emission maximum of from about 494.5 nm.







TABLE 2







lead-containing Eu2+-activated aluminate compared with Eu2+-activated


aluminate without lead at about 400 nm excitation wavelength











Compound



Lead-containing compound
without lead



Pb0.05Sr3.95Al14O25: Eu
Sr4Al14O25: Eu













Luminous density (%)
101.4
100


Wavelength (nm)
494.5
493
















TABLE 3







optical properties of some copper-and/or lead-containing aluminates


excitable by long wave ultraviolet and/or by visible light and their luminous


density in % at 400 nm excitation wavelength














Peak wave






length of lead-




Luminous density at 400 nm
and/or copper



Possible
excitation compared
containing
Peak wave length of



excitation
with compounds not
materials
materials without


Composition
range(nm)
containing copper/lead (%)
(nm)
lead/copper (nm)














Cu0.5Sr3.5Al14O25: Eu
360-430
101.2
495
493


Cu0.02Sr3.98Al14O25: Eu
360-430
103.1
494
493


Pb0.05Sr3.95Al14O25: Eu
360-430
101.4
494.5
493


Cu0.01Sr3.99Al13.995Si0.005O25:
360-430
103
494
492


Eu


Cu0.01Sr3.395Ba0.595Al14O25: Eu,
360-430
100.8
494
493


Dy


Pb0.05Sr3.95Al13.95Ga0.05O25: Eu
360-430
101.5
494
494









EXAMPLE 2
Luminescent materials for ultraviolet light or visible light excitation comprise lead and/or copper doped aluminates according to the formula as follows:

a(M′O).b(M′′O).c(Al2O3).d(M′′′2O3).e(M′′′′O2).f(M′′′′′xOy)  (5)

wherein M′ may be Pb, Cu, and/or any combination thereof; M′′ may be Be, Mg, Ca, Sr, Ba, Zn, Cd, Mn, and/or any combination thereof; M′′′ may be B, Ga, In, and/or any combination thereof; M′′′′ may be Si, Ge, Ti, Zr, Hf, and/or any combination thereof; M′′′′′ may be Bi, Sn, Sb, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and/or any combination thereof; 0<a≦1; 0≦b≦2; 0<c≦8; 0≦d≦1; 0≦e≦1; 0<f≦2; 1≦x≦2; and 1≦y≦5.
The luminous peak and density of Example 2 are described in Table 7, which will be shown below.
Example of Preparation:
Preparation of the Luminescent Material Having Formula (6)

Cu0.05Sr0.95Al1.9997Si0.0003O4:Eu  (6)

Starting materials: CuO, SrCO3, Al2O3, SiO2, Eu2O3, and/or any combination thereof.
The starting materials in the form of, for example, pure oxides and/or as carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, AlF3. The mixture may be fired in an alumina crucible at about 1,250° C. in a reduced atmosphere for about 3 hours. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum of about 521.5 nm.







TABLE 4







copper containing Eu2+-activated aluminate compared with Eu2+-


activated aluminate without copper at about 400 nm excitation wavelength











Compound



Compound containging copper
without copper



Cu0.05Sr0.95Al1.9997Si0.0003O4: Eu
SrAl2O4: Eu













Luminous density
106
100


(%)


Wavelength (nm)
521.5
519









Preparation of the Luminescent Material Having Formula (7)

Cu0.12BaMg1.88Al16O27:Eu  (7)

Starting materials: CuO, MgO, BaCO3, Al(OH)3, Eu2O3, and/or any combination thereof.
The starting materials in the form of, for example, pure oxides, hydroxides, and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, AlF3. The mixture may be fired in an alumina crucible at about 1,420° C. in a reduced atmosphere for about 2 hours. After that the material may be milled, washed, dried, and sieved. The resulting luminescent material may have an emission maximum of about 452 nm.







TABLE 5







copper-containing Eu2+-activated aluminate compared with copper not


doped Eu2+-activated aluminate at 400 nm excitation wavelength










Compound
Comparison



containing copper
without copper



Cu0.12BaMg1.88Al16O27: Eu
BaMg2Al16O27: Eu













Luminous density (%)
101
100


Wavelength (nm)
452
450









Preparation of the Luminescent Material Having Formula (8)

Pb0.1Sr0.9Al2O4:Eu  (8)

Starting materials: PbO, SrCO3, Al(OH)3, Eu2O3, and/or any combination thereof.
The starting materials in form of, for example, pure oxides, hydroxides, and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, H3BO3. The mixture may be fired in an alumina crucible at about 1,000° C. for about 2 hours in the air. After milling the pre-fired materials a second firing step at about 1,420° C. in the air for about 1 hour and in a reduced atmosphere for about 2 hours may be followed. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum of about 521 nm.







TABLE 6







lead-containing Eu2+-activated aluminate compared with Eu2+-


activated aluminate without lead at about 400 nm excitation wavelength










Lead-containing




compound
Compound without lead



Pb0.1Sr0.9Al2O4: Eu
SrAl2O4: Eu





Luminous density (%)
102
100


Wavelength (nm)
521
519









Results obtained in regard to copper and/or lead doped aluminates are shown in table 7.







TABLE 7







optical properties of some copper-and/or lead-containing aluminates


excitable by long wave ultraviolet and/or by visible light and their luminous density in % at 400 nm


excitation wavelength














Peak wave





Luminous density at
length of




Possible
400 nm excitation
lead/copper




excitation
compared with
doped
Peak wave length of



range
copper/lead not doped
materials
materials without


Composition
(nm)
compounds (%)
(nm)
lead/copper (nm)














Cu0.05Sr0.95Al1.9997Si0.0003O4: Eu
360-440
106
  521.5
519


Cu0.2Mg0.7995Li0.0005Al1.9Ga0.1O4:
360-440
101.2
482
480


Eu, Dy






Pb0.1Sr0.9Al2O4: Eu
360-440
102
521
519


Cu0.05BaMg1.95Al16O27: Eu, Mn
360-400
100.5
451, 515
450, 515


Cu0.12BaMg1.88Al16O27: Eu
360-400
101
452
450


Cu0.01BaMg0.99Al10O17: Eu
360-400
102.5
451
449


Pb0.1BaMg0.9Al9.5Ga0.5O17: Eu,
360-400
100.8
448
450


Dy






Pb0.08Sr0.902Al2O4: Eu, Dy
360-440
102.4
521
519


Pb0.2Sr0.8Al2O4: Mn
360-440
100.8
658
655


Cu0.06Sr0.94Al2O4: Eu
360-440
102.3
521
519


Cu0.05Ba0.94Pb0.06Mg0.95Al10O17:
360-440
100.4
451
449


Eu






Pb0.3Ba0.7Cu0.1Mg1.9Al16O27: Eu
360-400
100.8
452
450


Pb0.3Ba0.7Cu0.1Mg1.9Al16O27: Eu,
360-400
100.4
452, 515
450, 515


Mn









EXAMPLE 3
Luminescent materials for ultraviolet light or visible light excitation comprise lead and/or copper doped silicates according to the formula as follows:

a(M′O).b(M′′O).c(M′′′X).d(M′′′2O).e(M′′′′2O3).f(M′′′′′oOp).g(SiO2).h(M′′′′′′xOy)  (9)

wherein M′ may be Pb, Cu, and/or any combination thereof; M′′ may be Be, Mg, Ca, Sr, Ba, Zn, Cd, Mn, and/or any combination thereof; M′′′ may be Li, Na, K, Rb, Cs, Au, Ag, and/or any combination thereof; M′′′′ may be Al, Ga, In, and/or any combination thereof; M′′′′′ may be Ge, V, Nb, Ta, W, Mo, Ti, Zr, Hf, and/or any combination thereof; M′′′′′′ may be Bi, Sn, Sb, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and/or any combination thereof; X may be F, Cl, Br, I, and any combination thereof; 0<a≦2; 0<b≦8; 0≦c≦4; 0≦d≦2; 0≦e≦2; 0≦f≦2; 0<g≦10; 0<h≦5; 1≦o≦2; 1≦p≦5; 1≦x≦2; and 1≦y≦5.
The copper-containing silicates exemplarily described herein may, in some embodiments, contain SiO4 and be characterized as having an Olivine structure (orthorhombic) or β-K0.2SO4 structure (orthorhombic); contain Si2O8 and be characterized as having a trigonal Glaserite (K3Na(SO4)2) or monoclinic Merwinite structure; contain Si2O7 and be characterized as having a tetragonal Ackermanite structure; contain SiO5 and be characterized as having a tetragonal structure; and/or contain Si2O5 and be characterized as having an orthorhombic structure.
The superior luminous density of Example 3 can be seen below.
Example of Preparation:
Preparation of the Luminescent Material Having Formula (10)

Cu0.05Sr1.7Ca0.25SiO4: Eu  (10)

Starting materials: CuO, SrCO3, CaCO3, SiO2, Eu2O3, and/or any combination thereof.
The starting materials in the form of pure oxides and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, NH4Cl. The mixture may be fired in an alumina crucible at about 1,200° C. in an inert gas atmosphere (e.g., N2 or noble gas) for about 2 hours. Then the material may be milled. After that, the material may be fired in an alumina crucible at about 1,200° C. in a slightly reduced atmosphere for about 2 hours. Then, the material may be milled, washed, dried, and sieved. The resulting luminescent material may have an emission maximum at about 592 nm.







TABLE 8







copper-containing Eu2+-activated silicate compared with Eu2+-


activated silicate without copper at about 400 nm excitation wavelength










Copper-containing
Compound without



compound
copper



Cu0.05Sr1.7Ca0.25SiO4: Eu
Sr1.7Ca0.3SiO4: Eu





Luminous density (%)
104
100


Wavelength (nm)
592
588









Preparation of the Luminescent Material Having Formula (11):

Cu0.2Ba2Zn0.2Mg0.6Si2O7:Eu  (11)

Starting materials: CuO, BaCO3, ZnO, MgO, SiO2, Eu2O3, and/or any combination thereof.
The starting materials in the form of very pure oxides and carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, NH4Cl. In a first step the mixture may be fired in an alumina crucible at about 1,100° C. in a reduced atmosphere for about 2 hours. Then the material may be milled. After that the material may be fired in an alumina crucible at about 1,235° C. in a reduced atmosphere for about 2 hours. Then that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum at about 467 nm.







TABLE 9







copper-containing Eu2+-activated silicate compared with Eu2+-activated


silicate without copper at 400 nm excitation wavelength










Copper-containing compound
Compound without copper



Cu0.2Sr2Zn0.2Mg0.6Si2O7: Eu
Sr2Zn2Mg0.6Si2O7: Eu












Luminous
101.5
100


density (%)




Wavelength
467
465


(nm)









Preparation of the Luminescent Material Having Formula (12)

Pb0.1BaO0.95Sr0.95Si0.998Ge0.002O4:Eu  (12)

Starting materials: PbO, SrCO3, BaCO3, SiO2, GeO2, Eu2O3, and/or any combination thereof.
The starting materials in the form of oxides and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, NH4Cl. The mixture may be fired in an alumina crucible at about 1,000° C. for about 2 hours in the air. After milling the pre-fired materials a second firing step at 1,220° C. in air for 4 hours and in reducing atmosphere for 2 hours may be followed. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum at about 527 nm.







TABLE 10







lead-containing Eu2+-activated silicate compared with Eu2+-activated


silicate without lead at about 400 nm excitation wavelength











Compound



Lead-containing compound
without lead



Pb0.1Ba0.95Sr0.95Si0.998Ge0.002O4: Eu
BaSrSiO4: Eu












Luminous
101.3
100


density (%)




Wavelength (nm)
527
525









Preparation of the Luminescent Material Having Formula (13)

Pb0.25Sr3.75Si3O8Cl4:Eu  (13)

Starting materials: PbO, SrCO3, SrCl2, SiO2, Eu2O3, and any combination thereof.
The starting materials in the form of oxides, chlorides, and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, NH4Cl. The mixture may be fired in an alumina crucible in a first step at about 1,100° C. for about 2 hours in the air. After milling the pre-fired materials a second firing step at about 1,220° C. in the air for about 4 hours and in a reduced atmosphere for about 1 hour may be followed. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum at about 492 nm.







TABLE 11







lead-containing Eu2+-activated chlorosilicate compared with Eu2+-


activated chlorosilicate without lead at 400 nm excitation wavelength










Lead-containing compound
Compound without lead



Pb0.25Sr3.75Si3O8Cl4: Eu
Sr4Si3O8Cl4: Eu












Luminous
100.6
100


density (%)




Wavelength (nm)
492
490









Results obtained with respect to copper- and/or lead-containing silicates are shown in table 12.







TABLE 12







optical properties of some copper- and/or lead-containing rare earth


activated silicates excitable by long wave ultraviolet and/or by visible light and their luminous


density in % at about 400 nm excitation wavelength














Peak wave





Luminous density at
length




Possible
400 nm excitation
of lead-and/or
Peak wave length



excitation
compared with
copper-
of materials



range
copper/lead not doped
containing
without


Composition
(nm)
compounds (%)
materials (nm)
lead/copper (nm)














Pb0.1Ba0.95Sr0.95Si0.998Ge0.002O4:
360-470
101.3
527
525


Eu






Cu0.02(Ba,Sr,Ca,Zn)1.98SiO4:
360-500
108.2
565
560


Eu






Cu0.05Sr1.7Ca0.25SiO4: Eu
360-470
104
592
588


Cu0.05Li0.002Sr1.5Ba0.448SiO4:
360-470
102.5
557
555


Gd, Eu






Cu0.2Sr2Zn0.2Mg0.6Si2O7: Eu
360-450
101.5
467
465


Cu0.02Ba2.8Sr0.2Mg0.98Si2O8:
360-420
100.8
440, 660
438, 660


Eu, Mn






Pb0.25Sr3.75Si3O8Cl4: Eu
360-470
100.6
492
490


Cu0.2Ba2.2Sr0.75Pb0.05Zn0.8Si2O8:
360-430
100.8
448
445


Eu






Cu0.2Ba3Mg0.8Si1.99Ge0.01O8:
360-430
101
444
440


Eu






Cu0.5Zn0.5Ba2Ge0.2Si1.8O7: Eu
360-420
102.5
435
433


Cu0.8Mg0.2Ba3Si2O8: Eu, Mn
360-430
103
438, 670
435, 670


Pb0.15Ba1.84Zn0.01Si0.99Zr0.01O4:
360-500
101
512
510


Eu






Cu0.2Ba5Ca2.8Si4O16: Eu
360-470
101.8
495
491









EXAMPLE 4
Luminescent materials for ultraviolet light or visible light excitation comprise lead and/or copper-containing antimonates according to the formula as follows:

a(M′O).b(M′′2O).c(M′X).d(Sb2O5).e(M′′′O).f(M′′′′xOy)  (14)

wherein M′ may be Pb, Cu, and/or any combination thereof; M′′ may be Li, Na, K, Rb, Cs, Au, Ag, and/or any combination thereof; M′′′ may be Be, Mg, Ca, Sr, Ba, Zn, Cd, Mn, and/or any combination thereof; M′′′′ may be Bi, Sn, Sc, Y, La, Pr, Sm, Eu, Tb, Dy, Gd, and/or any combination thereof; X may be F, Cl, Br, I, and/or any combination thereof; 0<a≦2; 0≦b≦2; 0≦c≦4; 0≧d≦8; 0≦e≦8; 0<f≦2; 1≦x≦2; and 1≦y≦5.
Examples of Preparation:
Preparation of the Luminescent Material Having Formula (15)

Cu0.2Mg0.7Li0.2Sb2O7:Mn  (15)

Starting materials: CuO, MgO, Li2O, Sb2O5, MnCO3, and/or any combination thereof.
The starting materials in the form of oxides may be mixed in stoichiometric proportion together with small amounts of flux. In a first step the mixture may be fired in an alumina crucible at about 985° C. in the air for about 2 hours. After pre-firing the material may be milled again. In a second step the mixture may be fired in an alumina crucible at about 1,200° C. in an atmosphere containing oxygen for about 8 hours. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum at about 626 nm.







TABLE 13







copper-containing antimonate compared with antimonate without


copper at about 400 nm excitation wavelength










Copper-containing compound
Comparison without copper



Cu0.2Mg1.7Li0.2Sb2O7: Mn
Mg2Li0.2Sb2O7: Mn












Luminous
101.8
100


density (%)




Wavelength
652
650


(nm)









Preparation of the Luminescent Material Having Formula (16)

Pb0.006Ca0.6Sr0.394Sb2O6  (16)

Starting materials: PbO, CaCO3, SrCO3, Sb2O5, and/or any combination thereof.
The starting materials in the form of oxides and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux. In a first step the mixture may be fired in an alumina crucible at about 975° C. in the air for about 2 hours. After pre-firing the material may be milled again. In a second step the mixture may be fired in an alumina crucible at about 1,175° C. in the air for about 4 hours and then in an oxygen-containing atmosphere for about 4 hours. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum at about 637 nm.







TABLE 14







lead-containing antimonate compared with antimonate without lead at


400 nm excitation wavelength










Lead-containing compound
Compound without lead



Pb0.006Ca0.6Sr0.394Sb2O6
Ca0.6Sr0.4Sb2O6





Luminous
102
100


density (%)




Wavelength (nm)
637
638









Results obtained in respect to copper- and/or lead-containing antimonates are shown in table 15.







TABLE 15







optical properties of some copper and/or lead-containing antimonates


excitable by long wave ultraviolet and/or by visible light and their luminous density in % at


about 400 nm excitation wavelength













Luminous density






at 400 nm

Peak wave




excitation

length of




compared with
Peak wave length
materials



Possible
copper/lead not
of lead-and/or
without



excitation
doped compounds
copper-containing
lead/copper


Composition
range (nm)
(%)
materials (nm)
(nm)














Pb0.2Mg0.002Ca1.798Sb2O6F2: Mn
360-400
102
645
649


Cu0.15Ca1.845Sr0.005Sb1.998Si0.002O7:
360-400
101.5
660
658


Mn






Cu0.2Mg1.7Li0.2Sb2O7: Mn
360-400
101.8
652
650


Cu0.2Pb0.01Ca0.79Sb1.98Nb0.02O6: Mn
360-400
98.5
658
658


Cu0.01Ca1.99Sb1.9995V0.0005O7: Mn
360-400
100.5
660
657


Pb0.006Ca0.6Sr0.394Sb2O6
360-400
102
637
638


Cu0.02Ca0.9Sr0.5Ba0.4Mg0.18Sb2O7
360-400
102.5
649
645


Pb0.198Mg0.004Ca1.798Sb2O6F2
360-400
101.8
628
630









EXAMPLE 5
Luminescent materials for ultraviolet light or visible light excitation comprise lead- and/or copper-containing germanates and/or a germanate-silicates exemplarily characterized according to the formula as follows:

a(M′O)b(M′′2O)c(M′′X)dGeO2e(M′′′O)f(M′′′′2O3)g(M′′′′′oOp)h(M′′′′′′xOy)  (17)

wherein M′ may be Pb, Cu, and/or any combination thereof; M′′ may be Li, Na, K, Rb, Cs, Au, Ag, and/or any combination thereof; M′′′ may be Be, Mg, Ca, Sr, Ba, Zn, Cd, and/or any combination thereof; M′′′′ may be Sc, Y, B, Al, La, Ga, In, and/or any combination thereof; Mm′′′′′ may be Si, Ti, Zr, Mn, V, Nb, Ta, W, Mo, and/or any combination thereof; M′′′′′′ may be Bi, Sn, Pr, Sm, Eu, Gd, Dy, and/or any combination thereof; X may be F, Cl, Br, I, and/or any combination thereof; 0<a≦2; 0≦b≦2; 0≦c≦10; 0≦d≦10; 0≦e≦14; 0≦f≦14; 0≦g≦10; 0≦h≦2; 1≦o≦2; 1≦p≦5; 1≦x≦2; and 1≦y≦5.
Example of Preparation:
Preparation of the Luminescent Material Having Formula (18)

Pb0.004Ca1.99Zn0.006Ge0.8Si0.2O4:Mn  (18)

Starting materials: PbO, CaCO3, ZnO, GeO2, SiO2, MnCO3, and/or any combination thereof,
The starting materials in the form of oxides and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, NH4Cl. In a first step the mixture may be fired in an alumina crucible at about 1,200° C. in an oxygen-containing atmosphere for about 2 hours. Then, the material may be milled again. In a second step the mixture may be fired in an alumina crucible at about 1,200° C. in oxygen containing atmosphere for about 2 hours. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum at about 655 nm.







TABLE 16







lead-containing Mn-activated germanate compared with Mn-activated


germinate without lead at about 400 nm excitation wavelength











Comparison without



Copper-containing compound
copper



Pb0.004Ca1.99Zn0.006Ge0.8Si0.2O4:
Ca1.99Zn0.01Ge0.8Si0.2O4:



Mn
Mn












Luminous
101.5
100


density (%)




Wavelength
655
657


(nm)









Preparation of the Luminescent Material Having Formula (19)

Cu0.46Sr0.54Ge0.6Si0.4O3:Mn  (19)

Starting materials: CuO, SrCO3, GeO2, SiO2, MnCO3, and/or any combination thereof.
The starting materials in the form of oxides and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, NH4Cl. In a first step the mixture may be fired in an alumina crucible at about 1,100° C. in an oxygen-containing atmosphere for about 2 hours. Then, the material may be milled again. In a second step the mixture may be fired in an alumina crucible at about 1,180° C. in an oxygen-containing atmosphere for about 4 hours. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum at about 658 nm.







TABLE 17







copper-containing Mn-activated germanate-silicate compared with Mn-


activated germanate-silicate without copper at 400 nm excitation


wavelength











Compound



copper-containing compound
without copper



Cu0.46Sr0.54Ge0.6Si0.4O3: Mn
SrGe0.6Si0.4O3: Mn





Luminous density
103
100


(%)




Wavelength (nm)
658
655
















TABLE 18







optical properties of some copper and/or lead-containing germanate-


silicates excitable by long wave ultraviolet and/or by visible light and their luminous density in


% at about 400 nm excitation wavelength













Luminous density at






400 nm excitation
Peak wave
Peak wave



Possible
compared with
length of lead-
length of materials



excitation
copper/lead not
and/or copper-
without



range
containing
containing
lead/copper


Composition
(nm)
compounds (%)
materials (nm)
(nm)














Pb0.004Ca1.99Zn0.006Ge0.8Si0.2O4: Mn
360-400
101.5
655
657


Pb0.002Sr0.954Ca1.044Ge0.93Si0.07O4:
360-400
101.5
660
661


Mn






Cu0.46Sr0.54Ge0.6Si0.4O3: Mn
360-400
103
658
655


Cu0.002Sr0.998Ba0.99Ca0.01Si0.98Ge0.02O4:
360-470
102
538
533


Eu






Cu1.45Mg26.55Ge9.4Si0.6O48: Mn
360-400
102
660
657


Cu1.2Mg26.8Ge8.9Si1.1O48: Mn
360-400
103.8
670
656


Cu4Mg20Zn4Ge5Si2.5O38F10: Mn
360-400
101.5
658
655


Pb0.001Ba0.849Zn0.05Sr1.1Ge0.04Si0.96O4:
360-470
101.8
550
545


Eu






Cu0.05Mg4.95GeO6F2: Mn
360-400
100.5
655
653


Cu0.05Mg3.95GeO5.5F: Mn
360-400
100.8
657
653









EXAMPLE 6
Luminescent materials for ultraviolet light or visible light excitation comprise lead and/or copper-containing phosphates exemplarily characterized according to the formula as follows:

a(M′O)b(M′′2O)c(M′′X)dP2O5e(M′′′O)f(M′′′′2O3)g(M′′′′′O2)h(M′′′′′′xOy)  (20)

wherein M′ may be Pb, Cu, and/or any combination thereof; M′′ may be Li, Na, K, Rb, Cs, Au, Ag, and/or any combination thereof; M′′′ may be Be, Mg, Ca, Sr, Ba, Zn, Cd, Mn, and/or any combination thereof; M′′′′ may be Sc, Y, B, Al, La, Ga, In, and/or any combination thereof, Mm′′′′′ may be Si, Ge, Ti, Zr, Hf; V, Nb, Ta, W, Mo, and/or any combination thereof; M′′′′′′ may be Bi, Sn, Pr, Sm, Eu, Gd, Dy, Ce, Tb, and/or any combination thereof; X may be F, Cl, Br, I, and/or any combination thereof; 0<a≦2; 0≦b≦12; 0≦c≦16; 0<d≦3; 0≦e≦5; 0≦f≦3; 0≦g≦2; 0<h≦2; 1≦x≦2; and 1≦y≦5.
The luminescent materials comprising the lead and/or copper-containing phosphates may be used as compounds for ultraviolet light in a light emitting device.
Examples of Preparation:
Preparation of the Luminescent Material Having Formula (21)

Cu0.02Ca4.98(PO4)3Cl:Eu  (21)

Starting materials: CuO, CaCO3, Ca3(PO4)2, CaCl2, Eu2O3, and/or any combination thereof,
The starting materials in the form of oxides, phosphates, and/or carbonates and chlorides may be mixed in stoichiometric proportions together with small amounts of flux. The mixture may be fired in an alumina crucible at about 1,240° C. in reducing atmosphere for about 2 hours. After that the material may be milled, washed, dried and sieved. The luminescent material may have an emission maximum at about 450 nm.







TABLE 19







copper-containing Eu2+-activated chlorophosphate compared


with Eu2+-activated chlorophosphate without copper at about


400 nm excitation wavelength










Copper-containing
Compound



compound
without copper



Cu0.02Ca4.98(PO4)3Cl: Eu
Ca5(PO4)3Cl: Eu












Luminous density (%)
101.5
100


Wavelength (nm)
450
447
















TABLE 20







copper- and/or lead-containing phosphates excitable by long wave


ultraviolet and/or by visible light and their luminous density in % at about 400 nm excitation


wavelength













Luminous density at






400 nm
Peak wave length





excitation compared
of lead/copper-
Peak wave length



Possible
with copper/lead not
containing
of materials



excitation
doped compounds
materials
without


Composition
range (nm)
(%)
(nm)
lead/copper (nm)














Cu0.02Sr4.98(PO4)3Cl: Eu
360-410
101.5
450
447


Cu0.2Mg0.8BaP2O7: Eu, Mn
360-400
102
638
635


Pb0.5Sr1.5P1.84B0.16O6.84: Eu
360-400
102
425
420


Cu0.5Mg0.5Ba2(P,Si)2O8: Eu
360-400
101
573
570


Cu0.5Sr9.5(P,B)6O24Cl2: Eu
360-410
102
460
456


Cu0.5Ba3Sr6.5P6O24(F,Cl)2:
360-410
102
443
442


Eu






Cu0.05(Ca,Sr,Ba)4.95P3O12Cl:
360-410
101.5
438, 641
435, 640


Eu, Mn






Pb0.1Ba2.9P2O8: Eu
360-400
103
421
419









Lead- and/or copper-containing luminescent materials exemplarily described above can be act as converter for light emitting devices, such as ultraviolet as well as blue emitting LEDs, back lights and painting pigments. They can convert the excitation wavelength from the ultraviolet and blue light to longer visible wavelength. According to some embodiments, one or more of the lead- and/or copper-containing luminescent materials exemplarily described above may be used or mixed to produce a luminescent material with a color temperature ranging from about 2,000K to about 8,0000K or about 10,000K and superior color rendering index of greater than about 60 (e.g. between about 60 and about 90, or greater than about 90, or between about 90 and about 95). Thus, for all color temperatures as well as for all color coordinates inside of the white light coordinates, an appropriate luminescent material or mixture thereof can be found.

## Claims

1. A luminescent material for a light emitting diode (LED), comprising:
a first compound including a host lattice and a luminescent ion within the host lattice,
wherein the host lattice comprises first ions and oxygen,
wherein a first portion of the first ions is substituted by divalent copper ions,
wherein the first compound emits light upon excitation with ultraviolet light or visible light emitted by the LED,
wherein the first compound has a trigonal Glaserite (K3Na(SO4)2) crystal structure, a monoclinic Merwinite crystal structure, a tetragonal crystal structure, or an orthorhombic crystal structure, and
wherein the first ions comprise at least one of Be, Mg, Ca, Sr, Ba, Zn, Cd and Mn.

2. The luminescent material of claim 1, wherein the luminescent material has a color temperature ranging from about 2,000K to about 8,000K.

3. The luminescent material of claim 1, wherein the luminescent material has a color temperature of about 10,000K.

4. The luminescent material of claim 1, wherein the luminescent material has a color rendering index greater than about 60.

5. The luminescent material of claim 4, wherein the luminescent material has a color rendering index between about 60 and about 90.

6. The luminescent material of claim 4, wherein the luminescent material has a color rendering index greater than about 90.

7. The luminescent material of claim 1, wherein the luminescent ion comprises at least one of Bi, Sn, Sb, Sc, Y, La, In, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.

8. The luminescent material of claim 1, wherein the first compound comprises a silicate.

9. The luminescent material of claim 8, wherein the first compound comprises Ge.