HK1120286A - Aluminate-based blue phosphors - Google Patents

Abstract

Embodiments of the present invention are directed in general to novel aluminate-blue phosphors; specifically, use in white light illumination systems, and in display applications such as back lighting in liquid crystal displays (LCD's) and plasma display panels (PDPs). Embodiments of the present invention are further directed toward aluminate-based phosphors having the general formula (M1-XEux)2-ZMgZAlyO[1+(3/2)y], where M is a divalent alkaline earth metal other than magnesium (Mg) from group IIA of the periodic table, where 0.05＜x＜0.5; 3≤y≤12; and 0.8≤y≤1.2. In another embodiment, 0.2＜x＜0.5. The composition may contain a halogen, such as fluorine or chlorine. M may be either Ba (barium) or Sr (strontium); when M is Ba, the phosphor is a member of the present barium aluminate magnesium (BAM) series; when M is strontium, the phosphor is a member of the present strontium magnesium aluminate (SAM) series.

Description

Aluminate-based blue phosphor

Reference to related applications

This application is a partial continuation of U.S. patent application No. 10/912,741 entitled "Novel phosphor systems for a white Light Emitting Diode (LED)" filed on 8/4 2004 by inventors Yi Dong, Ning Wang, Shifan Cheng and Yi-Qun Li. U.S. patent application 10/912,741 is incorporated herein by reference in its entirety.

Technical Field

Embodiments of the present invention are generally directed to novel aluminate-blue phosphors (referred to herein as blue phosphors). In particular, embodiments of the present invention are directed to the use of the novel aluminate-based blue phosphors in white light illumination systems, back-lit display applications, signaling lights, and indicators, such as in Liquid Crystal Displays (LCDs), Plasma Display Panels (PDPs), and Cathode Ray Tube (CRT) displays.

Background

It has been proposed that white light illumination sources based in whole or in part on light emitting diodes will likely replace the common incandescent bulbs. These devices are often referred to as "white LEDs," but such a designation may be somewhat of a misnomer, because LEDs are typically components of a system that provide energy to another component, namely a phosphor (a component that emits light having more or less one color); it is possible to mix the light from several of the phosphors in addition to the light from the initially pumped LED to produce white light.

Nonetheless, white light LEDs are known in the art and are relatively recent innovations. Until LEDs emitting in the blue/ultraviolet region of the electromagnetic spectrum were developed, it became possible to fabricate LED-based white light illumination sources. From an economic point of view, white LEDs have the potential to replace incandescent light sources (light bulbs), especially as production costs are further reduced and the technology is further developed. In particular, white LEDs are believed to have a potential for longer life, robustness and efficiency over incandescent bulbs. For example, it is expected that an LED-based white light illumination source will be able to meet industry standards of 100,000 hour operating life and 80% to 90% efficiency. High brightness LEDs have had a substantial impact in replacing incandescent bulbs in social areas such as traffic light signals and, therefore, in the near future, it is not surprising that they will meet the general lighting requirements of homes and businesses, as well as other everyday applications.

In general, there are three general methods of making white LEDs. One approach is to combine the outputs of two or more LED semiconductor junctions, such as combining the outputs emitted by a blue LED and a yellow LED or more commonly a red, green and blue (RGB) LED. The first method does not use a phosphor. The second method is called phosphor conversion (phosphor conversion), in which light of a blue-emitting LED semiconductor junction is combined with light obtained from a phosphor excited by a blue LED. In the second case, some of the photons are down-converted by the phosphor to produce a broadband emission centered at the yellow frequency; the yellow color is then mixed with other blue photons of the blue-emitting LED to produce white light. In a third approach, a blue phosphor and at least one other phosphor, which is typically or includes a yellow phosphor, are excited using an LED that emits in a substantially invisible Ultraviolet (UV) portion of the electromagnetic spectrum.

Phosphors are well known and can be found in different applications such as CRT displays, UV lamps and flat panel displays. Phosphors function by absorbing some form of energy (which may be in the form of a beam of electrons or photons, or in the form of an electrical current) and then emitting energy in the form of light in a region having longer wavelengths in a process known as luminescence. To achieve the desired amount of fluorescence (brightness) emitted by a white LED, a high intensity semiconductor junction is required to sufficiently excite the phosphor so that it emits the desired color to mix that color with other emitted colors to form a beam that the human eye perceives as white light.

In many technical fields, the phosphor is zinc sulfide or yttrium oxide doped with a transition metal (such as Ag, Mn, Zn) or a rare earth metal (such as Ce, Eu or Tb). Transition metal and/or rare earth element dopants act as point defects (point defects) in the crystal, providing an intermediate energy state for electron occupation in the energy band gap of the material when electrons transition to and from a valence or conduction band state. The mechanism of such luminescence is associated with temperature-dependent fluctuations of the atoms in the crystal lattice, wherein oscillations (photons) of the lattice will cause displaced electrons to escape potential wells created by defects. It can emit light in the process when it relaxes to the initial state energy state.

Blue phosphors that have been used in the past in combination with near ultraviolet radiation sources have typically been divalent europium (Eu2+) activated barium magnesium aluminate (BAM) phosphors. These blue phosphors have been used in white light systems as well as in other applications, such as in Plasma Display Panels (PDPs), as blue-emitting components.

An example of a BAM phosphor is disclosed in U.S. Pat. No. 4,110,660, wherein a BaF-containing phosphor is fired at a temperature in the range of 1400 to 1650 ℃ F. under a hydrogen atmosphere₂、LiF、Al(OH)₃And Eu₂O₃For 3 to 6 hours. Another blue phosphor is described in U.S. patent 4,161,457 to k. This particular phosphor may be represented by the formula aMgO₂O₃Euo, wherein a, b, c and d are numbers which satisfy the condition a + b + c + d ═ 10, and wherein 0 < a ≦ 2.00; b is more than or equal to 0.25 and less than or equal to 2.00; 6.0≤c≤8.5；0.05≤d≤0.30。

Other blue phosphors that have been described in the art can be exemplified by lanthanum phosphate phosphors that use trivalent Tm as the activator, Li⁺And an optional amount of an alkaline earth element as a co-activator, as disclosed in r.p. rao in us patent 6,187,225. The exemplary blue phosphor may be represented by the formula (La)_1-x-zTm_xLi_yAE_z)PO₄Wherein x is more than or equal to 0.001 and less than or equal to 0.05; y is more than or equal to 0.01 and less than or equal to 0.05; and z is more than or equal to 0 and less than or equal to 0.05. More specifically, blue phosphors using Tm3+ and Li + doped lanthanum phosphate phosphors are considered to be part of the present invention, especially when made by sol-gel/xerogel and solid state processes.

Ono et al have described in U.S. Pat. No. 6,576,157 that Eu is the activator generally represented by the formula (Ba)_xM_1-x)_1-0.25yMg_1-yAl_10+yO_17+0.25yAnd wherein M represents Ca, Sr, or Ca and Sr, wherein the stoichiometric amounts of the constituent elements are represented by the relationships 0.5 ≦ x ≦ 1 and 0.05 ≦ y ≦ 0.15, and wherein the phosphor is excited by vacuum ultraviolet radiation.

Multiphase structured Eu has been prepared²⁺Activated La, Mg aluminate phosphor. It is disclosed in U.S. patent 4,249,108 that the raw material La can be treated at about 1500 to 1650 ℃ in a reducing atmosphere₂O₃、MgO、Al(OH)₃And Eu₂O₃The burning is carried out for about 1 to 5 hours. Other blue phosphors that may be used with the present green phosphor include those disclosed in U.S. Pat. No. 5,611,959, which teaches the inclusion of at least one element selected from the group consisting of Ba, Sr, and Ca; a Eu activator; mg and/or Zn; and optionally Mn. Such phosphors may be prepared by firing individual oxides and/or hydroxides in a reducing atmosphere at temperatures of 1200 to 1700 ℃ for 2 to 40 hours.

What is needed in the art is an improved blue phosphor capable of emitting light at higher intensities than currently available BAM materials. Improved blue phosphors with small changes in composition to change the emission wavelength are also desirable.

Disclosure of Invention

Embodiments of the invention include those having the formula (M)_1-xEu_x)_2-zMg_zAl_yO_[1+(3/2)y]The aluminate-based blue phosphor of (1); wherein M is at least one divalent metal selected from the group consisting of Ba and Sr. When M is Ba, the novel phosphor of the present invention may be referred to as BAM phosphor. Also, when M is Sr, the phosphor may be referred to as a SAM phosphor.

The relative amounts of M and Eu activator contained in the phosphor can be represented by the parameter "x", which will describe the contents of M and Eu in the stoichiometric formula in terms of atomic number. In one embodiment of the invention, 0.05 < x < 1. In another embodiment of the invention, 0.2 < x < 1. Since the prior art does not teach the high content of Eu mainly due to fluorescence quenching phenomenon (luminescence quenching phenomena), the concentration range of Eu is novel. Also, the amount of aluminum contained in the phosphors of the present invention can be described by the "y" parameter, and it has been found that the composition can be varied continuously over a range of 3. ltoreq. y.ltoreq.12, which is novel and advantageous. It has also been found that the blue phosphors of the present embodiments exhibit a host aluminate crystal structure that is substantially hexagonal in nature. In some embodiments, the value of Z may be in the range of about 0.8 to about 1.2, thus the stoichiometric amount of Mg in the formulation is about 1 mole per mole of the combined amount of M (Ba or Sr) and Eu.

The phosphors of the present invention have been constructed to absorb radiation having wavelengths in the range of about 280nm to 420nm and emit visible light having wavelengths in the range of about 420nm to 560 nm. In particular, the blue phosphors of the present invention have enhanced absorption and emission efficiencies in the near UV range (360-410nm) and visible blue (420-480nm) wavelengths, which would be beneficial for LED applications.

In addition, the present inventionAn illustrative embodiment includes a compound having the formula (M)_1-xEu_x)_2-zMg_zAl_yO_[1+(3/2)y]H, wherein M is at least one divalent metal selected from the group consisting of Ba and Sr. The "x", "y" and "z" parameters have the same values as described above. Halogen "H" may be fluorine, chlorine, bromine or iodine.

The aluminate-based blue phosphor in this embodiment is configured to be excitable by radiation emitted by an invisible or UV LED having a wavelength in the range of about 280 to 420 nm. The blue phosphor is configured to absorb at least a portion of the radiation from the radiation source and, in one embodiment, emits blue light at a peak intensity having a wavelength in the range of about 440 to 560; in another embodiment, light having a wavelength in the range of about 480 to 520nm is emitted; and in another embodiment emits light having a wavelength in the range of about 480 to 520 nm. Embodiments of the present invention include white light systems that utilize the blue phosphors of the present invention in combination with a source of invisible UV radiation and at least one other phosphor, which may be a yellow, green or red phosphor.

Drawings

FIG. 1 is a schematic representation of a prior art illumination system comprising a radiation source emitting visible light and a phosphor emitting light in response to excitation by the radiation source, wherein the light generated by the system is a mixture of the light of the phosphor and the light from the radiation source;

FIG. 2 is a schematic representation of an illumination system that includes a radiation source that emits non-visible light, so that light from the radiation source does not contribute to the light produced by the illumination system;

FIG. 3 is x-ray diffraction (XRD) data for a series of barium magnesium aluminate (BAM) phosphors of the present invention having different aluminum contents and higher contents of the activator Eu than those previously used in the art: the general stoichiometric formula of these phosphors is Ba_0.25Mg_0.5Eu_0.25Al_yO_[1+(3/2)y](ii) a Also shown are compounds of the formula BaMgAl₁₀O₁₇:Eu²⁺XRD data for conventional BAM shown;

FIGS. 4A and 4B are the emission and reflection spectra, respectively, of a series of Barium Aluminum Magnesium (BAM) phosphors of the present invention having different aluminum contents and represented by the formula Ba_0.25Mg_0.5Eu_0.25Al_yO_[1+(3/2)y]Represents;

FIG. 5 shows the emission spectra of another series of Barium Aluminum Magnesium (BAM) phosphors of the present invention having different aluminum contents, this time with the barium content set at a higher value than the BAM phosphors of FIGS. 4A-4B; the BAM phosphor of FIG. 5 is represented by the formula Ba_0.45Mg_0.5Eu_0.05Al_yO_[1+(3/2)y]Represents;

FIG. 6 shows the emission spectra of a series of the present Strontium Aluminum Magnesium (SAM) phosphors with different aluminum contents, which are prepared from Sr_0.25Mg_0.5Eu_0.2sAl_yO_[1+(3/2)y]Represents;

FIGS. 7A and 7B are graphs of the emission and reflection spectra, respectively, of a series of Barium Aluminum Magnesium (BAM) phosphors of the present invention in which the relative amounts of barium and Eu activator have been varied: these phosphors may be represented by the formula Ba_0.5-xEu_xMg_0.5Al₅O_8.5Represents;

FIG. 8 shows the emission spectra of a series of Strontium Aluminum Magnesium (SAM) phosphors of the present invention in which the relative amounts of strontium and Eu activator have been varied: these phosphors may be represented by the formula Sr_0.5-xEu_xMg_0.5Al₅O_8.5Represents;

FIG. 9 shows fluorine addition to a compound of formula_.25Mg_0.5Eu_0.25Al₅O_8.5The effect on excitation spectrum in a series of BAM phosphors;

FIG. 10 is a graph showing a heightEu activator content and having a composition Ba_0.25Eu_0.25Mg_0.5Al₅O_8.5A graph of the temperature dependence of the emission intensity of the phosphor of (a), indicating that the phosphor emits light at a relatively constant intensity over a wide temperature range;

FIG. 11 is an emission spectrum of a white LED containing the BAM phosphor of the present invention, wherein the data is compared to that of a white LED with a conventional BAM phosphor; and

FIG. 12 is a graph of emission intensity versus wavelength for a phosphor assembly comprising a phosphor having the formula (Sr)_0.5Eu_0.5)MgAl₁₀O₁₇And an orange phosphor (to be described in a separate invention) of the same inventor's invention, having the formula Sr₃SiO₅:EuF。

Detailed Description

Embodiments of the present invention are directed to compounds having the general formula (M)_1-xEu_x)_2-zMg_zAl_yO_[1+(3/2)y]Wherein M is a divalent alkaline earth metal other than magnesium (Mg) of group IIA of the periodic Table. In one embodiment, M may be Ba (barium) or Sr (strontium). When M is Ba, the phosphor is a member of the barium magnesium aluminate (BAM) series of the present invention; when M is strontium, the phosphor is a member of the strontium magnesium aluminate (SAM) family of the present invention. Embodiments of the invention may also include mixtures of BAM and SAM components.

One commonly used BAM phosphor may be of the formula BaMgAl₁₀O₁₇:Eu²⁺Denotes, i.e., a compound which has been used in fluorescent lamps, CRT displays, Plasma Display Panels (PDP) and possibly in light-emitting diodes (LED). In the prior art representative diagrams, the symbol "Eu²⁺"means that an amount of Eu activator as small as 2 atomic% is used as a dopant (see the article" Fluorescence of Eu, Blass et al)²⁺-activated alkoline-earth aluminates, "Philips research Reports volume 23, page 201-. The prior art teaches that the Eu content must be kept low in order to avoid the so-called "quenching effect".

The BAM of the present invention is distinguished from the known art in that the inventors of the present invention have surprisingly found that the Eu content can be greatly increased beyond the amount previously used without any detrimental effect taught by the quenching rules, i.e. an increase in Eu content will result in a decrease in the emission intensity of the phosphor. In fact, the inventors of the present invention have found that the exact opposite is true for BAM and SAM phosphors: increasing the Eu content beyond what was previously accepted will enable beneficial control of the emission and reflection characteristics of the phosphor.

Other embodiments of the present invention include the above-mentioned aluminate-based blue phosphors, which additionally include a halogen dopant; these phosphors may be represented by the formula M_1-xEu_xMg_0.5Al_yO_[1+(3/2)y]H represents; wherein H is a halogen of group VIIB of the periodic Table. In some embodiments of the invention, H may be F (fluorine), Cl (chlorine), Br (bromine) or I (iodine). Embodiments of the invention may also include a mixture of BAM and SAM components with halogen dopants.

In addition, the inventors of the present invention have found that the aluminum content in the phosphor composition can be varied continuously while preserving the host aluminate crystal structure. Without wishing to be bound by any particular theory, it is believed that this crystalline structure is hexagonal. In any case, the aluminum content is varied in such a way that the host aluminate crystal structure is substantially unchanged macroscopically. It is believed that altering the asymmetric local crystal structure will enhance the luminescent properties and still further advantageously control the emission and reflection properties of the phosphor.

Thus, the novel BAM and SAM phosphor series of the present invention, which have the ability to fine-tune the color output (fine-tube color output), can be used in a variety of applications where prior art BAM compositions are not suitable.

Embodiments of the invention will be described in the following order: an example of the utility of the present aluminate-based blue phosphors will first be discussed with emphasis on white LED illumination systems. Discussion of the utility will be followed by a summary of the present BAM/SAM phosphors, including the following novel characteristics: 1) many variations in aluminum content can be tolerated without substantially affecting the host crystal structure; 2) the content of Eu activator (relative to the divalent alkaline earth metal content) can be increased beyond what was previously taught; and 3) halogen dopants are also novel according to embodiments of the present invention. The characteristics of the light emitted by the phosphor can be advantageously controlled by varying the aluminum and europium content and optionally including a halogen.

Since a white LED using the aluminate-based blue phosphor of the present invention can be regarded as one of the most important market applications of the BAM and SAM phosphors of the present invention, the present invention will conclude by comparing the emission spectrum of a white LED using the aluminate-based blue phosphor of the present invention with that of a white LED having a conventional BAM for a blue phosphor.

Market applications for blue phosphors, including white LED lighting systems

Embodiments of the present invention are generally directed to novel aluminate-blue phosphors (referred to herein as blue phosphors). The novel aluminate-based blue phosphors of embodiments of the present invention are particularly useful in a variety of display applications, including white light display applications, back lighting in Liquid Crystal Displays (LCDs), Plasma Display Panels (PDPs), and Cathode Ray Tubes (CRTs), as well as projection displays, such as displays for televisions. Furthermore, it is also applicable to any separate blue LED use, such as decorative lights, sign lights (sign light), signal lights, indicators, and general lighting. The white light illumination system of embodiments of the present invention is dependent on the excitation source, which does not contribute substantially to the white light output of the system because it emits in a region of the electromagnetic spectrum that is invisible to the human eye. These concepts are schematically depicted in fig. 1 and 2.

Referring to prior art system 10 of fig. 1, radiation source 11, which may be an LED, emits light 12, 15 in the visible portion of the electromagnetic spectrum. Light 12 and 15 are the same light but are depicted as two separate beams for illustrative purposes. A portion of the light emitted by the radiation source 11, light 12, excites a phosphor 13, which is a photoluminescent material capable of emitting light 14 upon absorption of energy from the LED 11. The light 14 is typically yellow. Radiation source 11 also emits blue light in the visible region that phosphor 13 cannot absorb; this is the visible blue light 15 shown in fig. 1. The visible blue light 15 mixes with the yellow light 14 to provide the desired white light illumination 16 shown in the figure. A disadvantage of the prior art illumination system 10 of fig. 1 is that the color output of the system 10 depends on the output 15 of the radiation source 11.

If the white light emitted by the white light illumination system of the present invention does not emit radiation at wavelengths that are significantly visible to the human eye, the color output of the system does not vary significantly with the color output of the radiation source (e.g., LED). For example, and the LED may be configured to emit Ultraviolet (UV) radiation having a wavelength of 380nm or less that is not visible to the human eye. Furthermore, the human eye is less sensitive to UV radiation having a wavelength between about 380nm and 400nm, and is also substantially insensitive to violet light having a wavelength between about 400nm and 420 nm. Thus, radiation emitted by a light source having a wavelength of about 420nm or less will not substantially affect the color output of the white light illumination system.

This aspect of the invention is depicted in fig. 2. Referring to fig. 2, the substantially invisible light is the light 22, 23 emitted by the radiation source 21. The lights 22, 23 have the same characteristics, but different reference numerals are used to illustrate the following points: light 22 may be used to excite a phosphor, such as phosphor 24 or 25, while light 23 does not contribute to the color output 28 of the phosphor because the light 23 emitted by the radiation source 21 that does not impinge on the phosphor is substantially invisible to the human eye. In one embodiment of the invention, radiation source 21 is an LED that emits light having a wavelength generally in the range of about 350nm to 410 nm. In alternative embodiments, radiation sources having an excitation wavelength of at most 420nm are possible. Those skilled in the art will appreciate that near UV radiation of 400nm and higher can help to reproduce the color of white light emitted by a white LED if the intensity of the radiation source is sufficiently strong.

Another way to avoid affecting the color output of the white light illumination system 30 is to construct the luminescent materials 24, 25 (see fig. 2) to each have a thickness sufficient to prevent radiation of the LED 21 from passing through the materials. For example, if the LED emits visible light between about 420nm and 650nm, to ensure that the thickness of the phosphor does not affect the color output of the system, the phosphor should be thick enough to prevent any effective amount of visible radiation emitted by the LED from penetrating the phosphor.

Aluminate structure and aluminum content of novel blue phosphors

The blue phosphors of the present embodiments are based on various compositions having different aluminum contents. One novel characteristic of the phosphors of the invention is that the aluminum content can be varied within certain limits without substantially altering the host aluminate crystal structure. This can be confirmed by x-ray diffraction (XRD) as shown in fig. 3.

FIG. 3 shows a formula of Ba_0.25Mg_0.5Eu_0.25Al_yO_[1+(3/2)y]Wherein when the total number of atoms of divalent elements (e.g., Ba, Mg, and Eu) in the formula is equal to 1, the value of "y" is in the range of about 3 to about 12. Also shown in FIG. 3, below the drawing is a structural formula Ba_0.5Mg_0.5Al₅O_8.5:Eu²⁺XRD data for the conventional BAM shown (again, written by convention, where the total number of atoms of the divalent elements adds up to 1).

The data in fig. 3 show that while the aluminum content has changed for "y" values in the range of about 3 to about 12 (including the boundaries), the hexagonal crystal structure remains substantially unchanged throughout the series. Particular values for y in the composition as measured by x-ray diffraction are 3, 3.5, 4, 5,8, and 12, but one skilled in the art will recognize that any combination of the above compositions may exist and that "y" is not necessarily an integer value. Furthermore, the value of y need not be constant across any particular phosphor; in fact, experiments have shown that formulations with y values equal to 8 and 12 show the appearance of a second phase (second phase).

Writing a stoichiometric formulation of the present phosphors in another format may be beneficial to emphasize the fact that: the atomic ratio of aluminum to oxygen in the formula can be varied significantly without destroying the hexagonal nature of the host aluminate crystal structure. In these formulae, M is Ba or Sr. For example, an aluminate phosphor with y equal to 3 can also be written as (M)_1-xEu_xMg_0.5)₂Al₆O₁₁。

Alternatively, according to the previous nomenclature, the aluminate phosphors of the present invention may be provided according to embodiments of the present invention with y equal to 3.5, the phosphors thus having the formula (M)_1-xEu_xMg_0.5)Al₁₄O₂₅。

Alternatively, the aluminate phosphors of the present invention having y equal to 4 may be provided according to embodiments of the present invention, and thus the phosphors have the formula (M)_1-xEu_xMg_0.5)Al₄O₇。

Alternatively, the aluminate phosphors of the present invention having y equal to 5 may be provided according to embodiments of the present invention, and thus the phosphors have the formula (M)_1-xEu_xMg_0.5)₂Al₁₀O₁₇。

Alternatively, the aluminate phosphors of the present invention having y equal to 8 may be provided according to embodiments of the present invention, and thus the phosphors have the formula (M)_1-xEu_xMg_0.5)Al₈O₁₃。

Alternatively, the aluminate phosphors of the present invention having y equal to 12 may be provided according to embodiments of the present invention, and thus the phosphors have the formula (M)_1-xEu_xMg_0.5)Al₁₂O₁₉。

Although the data of fig. 3 have shown the case where M is Ba, the same tendency is found when the divalent alkaline earth metal M is strontium (Sr); in other words, changing the aluminum content and/or the ratio of aluminum to oxygen does not change the host crystal structure of the SAM phosphor. The flexibility of the aluminum content variation is significant in that it can be used to optimize the phosphor composition to meet the needs of a particular market application.

Although, as discussed above, varying the amount of aluminum content relative to the amount of divalent element (or, stated another way, the ratio of aluminum to oxygen) in the composition does not affect the hexagonal nature of the bulk aluminate crystal structure, it can have a profound effect on emission and reflection characteristics. FIGS. 4A and 4B are diagrams of compounds represented by formula Ba having different aluminum contents_0.25Mg_0.5Eu_0.25Al_yO_[1+(3/2)y]A series of emission and reflection spectra of the Barium Aluminum Magnesium (BAM) phosphors of the present invention are shown; where y has an exemplary value in the range of y 3 to 12 (including the border). In these exemplary compositions, the total content of divalent elements amounts to 1, and the amount of barium plus europium is approximately equal to the amount of magnesium. The excitation wavelength used to produce the emission and reflection spectra of fig. 4A and 4B is about 400 nanometers (nm).

The experimental arrangement can be briefly described as follows: directing excitation radiation at 400nm to a sample, wherein a portion of the radiation is reflected from the sample back to a detector; and a portion of the radiation is absorbed by the sample. Of course, the reflected radiation also has the same wavelength of about 400nm as the excitation radiation. The absorbed radiation may excite electrons across the band gap of the material, causing a so-called "down-conversion" process, so the material emits photons of lower energy (and hence longer wavelength; e.g., about 450nm to about 460nm) in a geometric direction (also toward the detector).

The data in FIG. 4A shows that the wavelength at which peak emission occurs decreases slightly as the amount of aluminum (expressed in terms of the "y" parameter) increases from 3 to 4, i.e., from about 468nm to about 460 nm; a further increase in the amount of aluminium content (to y-12) will cause the wavelength at which the peak emission occurs to increase to an intermediate value between 460 and 480 nm. Similarly, the peak intensity increases significantly from y 3 to y 4, and then decreases to an intermediate value of the relative intensity as the aluminum content further increases to 12.

Interestingly, the reflectance data in fig. 4B exhibited slightly different tendencies. It is found in fig. 4B that the wavelength at which the reflection peak occurs increases as the aluminum content reaches 12 from 3. Also, the reflection intensity is continuously increased throughout the series.

The trends discussed in fig. 4A and 4B relate to a fixed amount of divalent elements, where the barium and europium content is equal to the magnesium content, and where the total divalent element content is 1 (in atomic number); the question is what happens at different barium contents? FIG. 5 provides data for answering the question, and FIG. 5 is a series of data represented by formula Ba_0.45Eu_0.05Mg_0.5Al_yO_[1+(3/2)y]A graph of the emission spectrum shown. In this case, the composition of y ═ 3.5 exhibits the highest emission intensity and the shortest peak emission wavelength, and the composition of y ═ 6 has the lowest intensity and the longest peak emission wavelength. The peak emission wavelength and intensity of the composition with a y value between 3.5 and 12 is in an intermediate state.

Just as the relative amount of Ba to Eu in the BAM phosphor may vary, the relative amount of Sr to Eu in the SAM phosphor may also vary. FIG. 6 is the composition Sr_0.25Eu_0.25Mg_0.5Al_yO_[1+(3/2)y]Which is a similar pattern to the emission spectrum of the BAM shown in fig. 4A. As in the case of Ba, the peak emission wavelength shifts slightly from a higher value (about 473nm) to a lower value (about 465nm) as the aluminum content decreases within y-3 to y-5. The composition of y-4 was found to have the maximum emission intensity, which is the same as that found for the BAM series. However, the results of the SAM series shown in fig. 6 are different from those of the BAM series of fig. 4A in that europium quenching begins to develop itself gradually as the aluminum content in the composition where y is greater than about 5 increases, and thus emission intensities of y-8 and y-12 are not shown in fig. 6.

Although not shown graphically, SAM reflection series with different aluminum content exhibit the same trend as BAM series: the height of the reflection peak decreases with decreasing aluminum content.

Fig. 4A, 4B, 5 and 6 show how the emission and reflection behavior of the novel BAM and SAM phosphors can be optimized to meet the appropriate market demand by varying the varying aluminum content in the phosphors. Advantageously, it has been shown that the hexagonal crystal structure of the aluminate host is not altered by this optimization.

Relative content of group IIA alkaline earth metal to activator

The novel phosphors of the embodiments of the present invention may be represented by the formula (M)_1-xEu_x)_2-zMg_zAl_yO_[1+(3/2)y]Wherein the "x" parameter represents the relative amounts of alkaline earth metal M (excluding magnesium) and the Eu activator. It has been proposed above that the BAM and SAM phosphors of the present invention may differ from known techniques in that: eu content has been increased significantly beyond the amounts previously used, and surprisingly, the deleterious effects taught by the "quenching rule" do not occur. As will be shown in the present section, increasing the Eu content beyond the previously accepted levels will enable advantageous control of the emission and reflection characteristics of the phosphor.

Emission and reflection spectra of exemplary BAMs of embodiments of the invention are shown in fig. 7A and 7B, which demonstrate the effect of different Ba and Eu contents. The composition tested in this series of experiments may consist of the stoichiometric formula Ba_0.5-xEu_xMg_0.5Al₅O_8.5And (4) showing. Also, this formula has been written in a form such that the amount of all divalent elements totals the number 1 (in terms of atomic number). To illustrate the concept of relative Ba and Eu content, the amount of aluminum has been kept fixed in each composition of the present series. It should be noted that if the formula is written in another form as discussed above, the aluminate host hexagonal crystal will adopt Al₁₀O₁₇In the form of (1).

Referring to fig. 7A, one skilled in the art will appreciate that as the Eu content increases from x 0.05 to x 0.5, the wavelength at which the emission peak maximum occurs shifts from about 450nm to about 470 nm. In the Eu content range, the height of the emission peak increases first, reaching the strongest emission at compositions x ═ 0.2 to x ═ 0.3. Subsequently, as more Eu is added to reach a composition of x ═ 0.5, the emission intensity decreases.

FIG. 7B shows a signal from Ba_0.5-xEu_xMg_0.5Al₅O_8.5Reflectance spectra of the compound series shown. In this figure, as the Eu content increases from x ═ 0.05 to x ═ 0.5, the intensity of the reflection peak decreases in order.

Has the composition Sr in FIG. 8_0.5-xEu_xMg_0.5Al₅O_8.5The SAM phosphor of (a) exhibits a similar tendency to the BAM phosphor of fig. 7A. As the Eu content increases from x 0.05 to x 0.5, the wavelength at which the maximum of the emission peak occurs shifts from about 465nm to about 478 nm. Within the Eu content range, the height of the emission peak first increases (same as in the case of BAM series), the strongest emission is also achieved at a composition of x 0.2 to x 0.3, and subsequently, the emission intensity decreases as more Eu is added to achieve a composition of x 0.5.

Although not shown graphically, SAM reflection series with different europium content exhibit the same trend as BAM series: the height of the reflection peak decreases with increasing Eu content.

Overall, when x varies from 0.05 to 0.5, the maximum emission is reached for both the BAM and SAM composition series if the Eu content is between about x-0.2 and 0.3 and the wavelength shift of the emitted light ranges from about 28nm for the BAM series and 14nm for the SAM series. Thus, FIGS. 7A, 7B, and 8 show that the composition of the BAM and SAM phosphors can be optimized to achieve low reflection, high brightness, and desired output color. This ability to fine-tune the composition with respect to brightness and color is particularly useful for white LED applications.

Effect of halogen dopant in phosphor of the present invention

According to the inventionEmbodiments include aluminate-based blue phosphors that additionally include a halogen dopant; these phosphors may be represented by the formula (M)_1-xEu_x)_2-zMg_zAl_yO_[1+(3/2)y]H represents; wherein H is a halogen of group VIIB of the periodic Table. In some embodiments of the invention, H may be F (fluorine), Cl (chlorine), Br (bromine) or I (iodine). The halogen atoms may be present in substitution at the main lattice sites or as interstitial components (referred to as "addenda" in the present invention). Whether the halogen is present as an "addition" or as a "substitution", it was found that the presence of the halogen plays an important role in the behavior of the phosphor.

Embodiments of the invention may also include mixtures of BAM and SAM components with halogen dopants.

The effect of including a halogen dopant in a BAM phosphor according to embodiments of the present invention will be described in table 1 and fig. 9.

TABLE 1

Ba with halogen dopant_0.25Eu_0.25Mg_0.5Al₅O_8.5Emission intensity of

Fluorine precursor	Amounts (mol) included	Including type	Emission intensity (A.U.)	Reflection intensity (A.U.)
					Is free of	Is free of	Is free of	810	3450
AlF3	0.1	Additive	1000	3300
					AlF3	0.2	Additive	1020	3000
AlF3	0.3	Additive	900	3600
					AlF3	0.4	Additive	920	3750
MgF2	0.05	Substituent(s)	880	3200
					MgF2	0.10	Substituent(s)	890	3550
MgF2	0.15	Substituent(s)	880	3600
					BaF2	0.10	Substituent(s)	950	3600
BaF2	0.15	Substituent(s)	1040	3500

While not wishing to be bound by any particular theory, the data in table 1 indicate that the halogen may be present as an interstitial component (i.e., "addendum" in table 1) or alternatively to the bulk aluminate crystal, where the halogen atoms are located at lattice points of the crystal. Either way, the presence of the halogen affects the emission and reflection characteristics of the phosphor.

The effect of including halogens can also be represented graphically. FIG. 9 is a formula of Ba_0.25Eu_0.25Mg_0.5Al₅O_8.5The excitation spectrum of BAM (a), wherein the intensity of 460nm light emitted by the phosphor is plotted as a function of the wavelength of the excitation radiation. Fig. 9 shows that inclusion of halogen fluorine does have an effect on the emission intensity of the BAM phosphor.

Temperature dependence of emission intensity

It will be apparent to those skilled in the art that the emission intensity of the phosphor should desirably be substantially independent of temperature. Certain market applications of phosphors, such as high-energy LEDs, may require the phosphors to be used at high temperatures up to 200 ℃, and the phosphors should optimally exhibit relatively constant emission intensity over a wide temperature range, including high temperatures that challenge market applications.

As illustrated in fig. 10, the aluminate-based blue phosphor of the present invention can exhibit the temperature stability. The inventors of the present invention have found that using a phosphor having a relative emission intensity of about 100% as tested at about 20 degrees celsius, the intensity (in arbitrary units) decreases by no more than about 4% as the test temperature increases to 200 degrees celsius.

Near UV radiation source

In general, the aluminate-based blue phosphors of the present embodiments are not particularly responsive to excitation radiation having a wavelength greater than about 420 nm. According to embodiments of the invention, the near UV LED emits light substantially in the non-visible portion of the electromagnetic spectrum, e.g., radiation having a wavelength of up to about 420 nm. The LED may comprise any semiconductor diode based on a suitable II-V, II-VI or IV-IV semiconductor multilayer with semiconductor junctions having emission wavelengths below 420nm and 420 nm. For example, an LED may contain at least one semiconductor layer based on GaN, ZnSe, or SiC semiconductor. The LED may also optionally contain one or more quantum wells in the active region. Preferably, the LED active region may comprise a p-n junction comprising GaN, AlGaN, and/or InGaN semiconductor layers. The p-n junctions may be separated by a thin layer of undoped InGaN or one or more InGaN quantum wells. The LED may have an emission wavelength between 300 and 420nm, preferably between 340 and 405 nm. For example, an LED may have the following wavelengths: 350. 355, 360, 365, 370, 375, 380, 390, 405 or 410.

The near-UV excitation device of embodiments of the present invention is generally described herein as "LEDS", but those skilled in the art will appreciate that the source of the excitation radiation may be at least one of an LED, a laser diode, a surface emitting laser diode, a resonant cavity light emitting diode, an inorganic electroluminescent device, and an organic electroluminescent device (where it is contemplated to have several operations simultaneously).

Yellow phosphor in combination with the inventive blue BAM and SAM phosphors

The Yellow phosphor that may be used in the white LED lighting system may be a conventional Yttrium Aluminum Garnet (YAG) phosphor as previously described in the prior art, or it may comprise a phosphor as described in U.S. patent application No. Novel silicon-Based Yellow-Green Phosphors, filed on 9/22/2004, which is incorporated herein by reference (attorney docket No. 034172-. Such yellow phosphors are configured to absorb at least a portion of the radiation from the radiation source and emit light having a peak intensity in the wavelength range of about 530 to 590 nm.

Red and green phosphors in combination with the present blue phosphor

Many red phosphors known in the art can be used in combination with the aluminate-based blue phosphors of the present invention in a white light illumination system. One red phosphor that can be used is selected from the group consisting of CaS Eu²⁺、SrS:Eu²⁺、MgO*MgF*GeO:Mn⁴⁺And M_xSi_yN_z:Eu⁺²Wherein M is selected from the group consisting of Ca, Sr, Ba, and Zn; 2/3x +4/3y, and wherein the red phosphor is configured to absorb at least a portion of the radiation from the radiation source and emit light having a peak intensity in the wavelength range of about 590-690 nm.

Can be combined with bookThe inventive aluminate-based blue phosphors use a combination of a green phosphor comprising an aluminate oxide or an alkaline earth metal silicate, and a rare earth metal activator, such as europium in the +2 valence state (e.g., Eu)²⁺). For example, early h.lange in the disclosure of U.S. patent 3,294,699 describes europium (II) oxide activated strontium aluminate compositions wherein the amount of europium oxide added to the strontium aluminate is between about 2 and 8 mole percent. The specific luminescent material is 0.9 SrO.Al₂O₃0.03EuO, which was demonstrated to emit light in a broad band spectrum with a peak response in the green range of about 520 nanometers when excited by 365 nanometer (nm) mercury lines.

Another green phosphor that may be used in combination with the aluminate-based blue phosphor of the present invention is described in U.S. patent 6,555,958 to a.m. srivastava et al. Silicate-based blue-green phosphors and aluminate-based blue-green phosphors are disclosed in the patent, the aluminate-based composition being generally of the formula AAlO Eu²⁺Wherein A comprises at least one of Ba, Sr, or Ca. The preferred composition disclosed in said patent is AAl₂O₄:Eu²⁺Wherein A comprises at least 50% Ba, preferably at least 80% Ba and 20% or less Sr. When a contains Ba, the phosphor peak emission wavelength is about 505nm and the phosphor quantum efficiency is "high". When a contains Sr, the phosphor peak emission wavelength is about 520nm and the phosphor quantum efficiency is "quite high". Thus, it is disclosed in said patent that a most preferably contains Ba to obtain a peak wavelength close to 505nm and to obtain the highest relative quantum efficiency. It is also disclosed that in the alkaline earth metal aluminate phosphor, the europium activator is substituted at the alkaline earth metal lattice sites, so that the phosphor can be written as (A)_1-xEu_x)Al₂O₄Wherein x is more than 0 and less than or equal to 0.2. The most preferred phosphor composition is (Ba)_1-xEu_x)Al₂O₄Wherein x is more than 0 and less than or equal to 0.2. The compositions disclosed in the patents do not contain magnesium or manganese.

Kitamura et al, U.S. Pat. No. 5,879,586, discloses a green phosphor according to the formula (Ce)_1-wTb_w)Mg_xAl_yO_zThe rare earth metal component of the phosphor is cerium and terbium, wherein w is more than or equal to 0.03 and less than or equal to 0.6; x is more than or equal to 0.8 and less than or equal to 1.2; y is more than or equal to 9 and less than or equal to 13; and z is more than or equal to 15 and less than or equal to 23. This terbium-containing compound is reported to emit "high brightness green light," but does not provide relative intensity and peak emission wavelength, and does not contain europium as an active rare earth metal element. A "high brightness blue-green" emitting phosphor with strontium as the alkaline earth metal and europium as the activator is represented by the formula (Sr)_4(1-w)Eu_4w)Al_xO_yWherein w is more than or equal to 0.01 and less than or equal to 0.6; x is more than or equal to 11 and less than or equal to 17; and 20. ltoreq. y.ltoreq.30, but again without providing relative intensities and peak emission wavelengths.

Gallate-sulfide based green phosphors have been disclosed. In U.S. patent 6,686,691 to g.o.mueller et al, a device is disclosed that includes a green phosphor and a blue LED (the green phosphor absorbs the blue light of the blue LED). In one embodiment, the green phosphor is based on a host sulfide material; in other words, a lattice including sulfide ions. Preferred host sulfide materials are thiogallates such as SrGa₂S₄And when activated with a rare earth metal europium, a green phosphor SrGa₂S₄Eu exhibits a spectrum having a luminescence equivalent value of about 575lm/W at a maximum wavelength of about 535 nm. SrGa₂S₄The concentration of the dopant (rare earth metal Eu) in the host is preferably about 2 mol% to 4 mol%. The blue LED providing excitation radiation to the green phosphor is an (In, Ga) N diode emitting radiation at a wavelength of about 450 to 480 nm.

Lowery has been described in published U.S. application 2004/0061810 as a similar strontium-sulfide-based phosphor for LCD backlighting. In that application, the wavelength converting material selected to absorb light emitted by the LED die active region may be the strontium gallate sulfide phosphor, or a nitridosilicate (nitridosilicate) phosphor, described above. Strontium gallate sulfide phosphors have a dominant emission wavelength of about 542 nm. The wavelength converting material absorbs blue light from the LED die in the region of about 420 to 460nm, or in other embodiments in the range of about 380 to 420 nm. In addition, these devices containing green-emitting phosphors eliminate problems encountered with green LEDs, such as high temperature stability and temperature-induced color changes.

Ezuhara et al, U.S. patent 6,805,814, describes a green-emitting phosphor or its use in plasma displays, the phosphor being of the formula M¹ _1-aM² _11-bMn_a+bO_18-(a+b)/2Is represented by the formula, wherein M¹Is at least one of La, Y and Gd, and M²Is at least one of Al and Ca. In the case where the phosphor contains Al, wherein the phosphor is an aluminate, the alumina has a purity of not less than 99.9%, and a crystal structure of alpha alumina or intermediate alumina such as aluminum hydroxide. The peak emission wavelength of these green light-emitting phosphors is not provided. The excitation wavelength is in the range of vacuum ultraviolet light.

Green Phosphors that may be used in combination with the Aluminate-based blue Phosphors of the present invention in white light illumination systems have been described in U.S. patent application "Novel Aluminate-based Phosphors" (attorney docket No. 034172-029), filed on 14/1/2005, which is incorporated herein by reference.

Assembling together: white LED based on the blue phosphor of the present invention

Advantages of the present BAM and SAM blue phosphors include their ability to provide the colors required for white LED illumination systems. The optical characteristics of a white LED system using the blue aluminate-based phosphor of the present invention are depicted in fig. 11.

Method for producing phosphor

The method of manufacturing the novel aluminate-based phosphor of the present embodiments is not limited to any one manufacturing method, but may be manufactured, for example, in a three-step method including: 1) blending raw materials; 2) firing the raw material mixture; and 3) subjecting the fired material to various treatments including grinding and drying. The raw materials may comprise various kinds of powders such as alkaline earth metal compounds, aluminum compounds, and europium compounds. Examples of the alkaline earth metal compound include alkaline earth metal carbonates, nitrates, hydroxides, oxides, oxalates, and halides. Examples of the aluminum-containing compound include nitrates, fluorides, and oxides thereof. Examples of the europium compound include europium oxide, europium fluoride, and europium chloride.

The raw materials are blended in a manner to achieve the desired final composition. For example, in one embodiment, an alkaline earth metal, aluminum-containing compound (and/or germanium), and europium compound are blended in the appropriate ratios and then fired to obtain the desired composition. The blended raw materials are fired in a second step, and a flux may be used to enhance the reactivity of the blended materials (at any or various stages of firing). The flux may comprise various types of halides and boron compounds, examples of which include strontium fluoride, barium fluoride, calcium fluoride, europium fluoride, ammonium fluoride, lithium fluoride, sodium fluoride, potassium fluoride, strontium chloride, barium chloride, calcium chloride, europium chloride, ammonium chloride, lithium chloride, sodium chloride, potassium chloride, and combinations thereof. Examples of boron-containing flux compounds include boric acid, boron oxide, strontium borate, barium borate, and calcium borate.

In some embodiments, an amount of flux compound is used wherein the mole percent number is in the range of about 0.01 to 0.2 mole percent, wherein values may generally be in the range of about 0.01 to 0.1 mole percent, inclusive.

Various techniques for mixing the raw materials (with or without flux) include mixing using a mortar, mixing with a ball mill, mixing using a V-blender, mixing using a cross-rotating shaft mixer, mixing using a jet mill, and mixing using a stirrer. The raw materials may be mixed by dry mixing or wet mixing, wherein dry mixing refers to mixing performed without using a solvent. Solvents that may be used in the wet mixing process include water or organic solvents, where the organic solvent may be methanol or ethanol.

The mixture of raw materials can be fired by a variety of techniques known in the art. A heater such as an electric furnace or a gas furnace may be used for firing. The heater is not limited to any particular type as long as it can fire the raw material mixture at a desired temperature for a desired length of time. In some embodiments, the firing temperature may be in the range of about 800 to 1600 ℃. The firing time may be in the range of about 10 minutes to 1000 hours. The firing atmosphere may be selected from air, a low pressure atmosphere, a vacuum, an inert gas atmosphere, a nitrogen atmosphere, an oxygen atmosphere, an oxidizing atmosphere, and/or the composition may be fired in a reducing atmosphere at a temperature of 100 to 1600 ℃ for about 2 to 10 hours.

One method of making aluminate-based blue phosphors is directed to making phosphors having the formula M_1-xEu_xAl_yO_1+3y/2Wherein M is at least one divalent metal selected from the group consisting of Ba, Sr, Ca, Mg, Mn, Zu, Cu, Cd, Sm, and Tm; wherein x is more than 0.1 and less than 0.9, and y is more than 2 and less than 12. The method of preparing the phosphor may be one of a sol-gel method or a solid-phase reaction method. In the method, a metal nitrate may be used to provide the divalent metal component of the green phosphor, and to provide the aluminum component of the aluminate-based green phosphor. The metal nitrate providing the divalent metal component may be Ba (NO)₃)₂、Mg(NO₃)₂、Sr(NO₃)₂Or Ca (NO)₃)₂And the metal nitrate providing aluminum may be Al (NO)₃)₃。

The method additionally comprises the step of using the metal oxide to provide the oxygen component of the aluminate-based green phosphor.

An example of the method includes the steps of:

a) providing a signal selected from the group consisting of Ba (NO)₃)₂、Mg(NO₃)₂、Ca(NO₃)₂、Sr(NO₃)₂、Al(NO₃)₃And Eu₂O₃Raw materials of the group;

b) eu is mixed₂O₃Dissolving in a nitric acid solution and then mixing a desired amount of metal nitrate to form an aqueous nitrate solution;

c) heating the solution of step b) to form a gel;

d) heating the gel of step c) to about 500-; and

e) sintering the powder in step d) in a reducing atmosphere at a temperature of about 1000-1500 ℃ for about 1 to 10 hours.

Next, a general description of the CIE diagram and a description of the situation where the present blue phosphor appears on the CIE diagram will be provided.

Chromaticity coordinates and CRI on CIE diagram

Color quality can be measured by a number of different rating systems. Chroma defines color by hue and saturation. The CIE is a chromaticity coordinate system established by the Commission International de l' Eclairage (International Commission on illumination). The CIE chromaticity coordinates are coordinates that define colors in the "1931 CIE" color space. These coordinates are defined as x, y, z and are the ratio of the standard three primary colors X, Y, Z (tristimulus values) relative to the sum of the three tristimulus values. The CIE diagram contains a diagram of the x, y and z ratios of the tristimulus values to their sum. In the case where reduced coordinates (reduced coordinates) x, y, and z are added to 1, a two-dimensional CIE (x, y) diagram is generally used.

For display applications related to the blue phosphors of the present invention, the color space is independent of the position of the red, green, and blue light components in the color space. The blue phosphors of the present embodiments are particularly useful for creating a larger color space conducive to RGB backlit displays (known in the art as "wide color gamut displays"). Color coordinates within the stated range of values have a higher luminous efficiency which is clearly of benefit for the lighting and display industry.

The use of invisible UV LED chips with multi-color phosphors is one of the best approaches for all different white LED applications. By this method, superior color reproduction CRI and more uniform and controllable white light can be achieved than the conventional yellow phosphor method using blue LED chips. The present blue phosphor with higher efficiency in the near UV range will play a crucial role for white LEDs using the UV chip approach. A display of the white LED spectrum from a component of a 405nm UV chip and the present BAM phosphor and yellow or orange phosphor combination is shown in FIG. 11. FIG. 12 shows a display of a white LED spectrum from a component of a 405nm UV chip and the present SAM phosphor and yellow or orange phosphor combination.

FIG. 12 is a graph of emission intensity versus wavelength for a phosphor assembly comprising a phosphor having the formula (Sr)_0.5Eu_0.5)MgAl₁₀O₁₇The present blue phosphor and the same inventor's inventive orange phosphor (to be described in a separate invention) having the formula Sr₃SiO₅EuF. The excitation wavelength was 395 nm. The phosphor assembly exhibits a maximum intensity in the blue region of the electromagnetic spectrum at about 460 to 480nm, and a sub-maximum in the orange region at about 580 to 600 nm.

Numerous modifications to the exemplary embodiments of the invention disclosed above will be readily apparent to those skilled in the art. Accordingly, the invention is to be construed as including all such structures and methods as fall within the scope of the appended claims.

Claims (6)

1. Has the formula (M)_1-xEu_x)_2-zMg_zAl_yO_[1+(3/2)y]The aluminate-based blue phosphor of (1), wherein:

m is at least one divalent metal selected from the group consisting of Ba and Sr;

wherein

0.05＜x＜0.5；

3≤y≤12；

Y is more than or equal to 0.8 and less than or equal to 1.2, and

wherein the phosphor is configured to absorb radiation having a wavelength in the range of about 280nm to 420nm and to emit visible light having a wavelength in the range of about 420nm to 560 nm.

2. The blue phosphor of claim 1, wherein the host aluminate crystal structure is substantially a hexagonal crystal structure.

3. Has the formula (M)_1-xEu_x)_2-zMg_zAl_yO_[1+(3/2)y]The aluminate-based blue phosphor of (1), wherein:

m is at least one divalent metal selected from the group consisting of Ba and Sr;

wherein

0.2＜x＜0.5；

3≤y≤12；

Y is more than or equal to 0.8 and less than or equal to 1.2, and

wherein the phosphor is configured to absorb radiation having a wavelength in the range of about 280nm to 420nm and to emit visible light having a wavelength in the range of about 420nm to 560 nm.

4. Has the formula (M)_1-xEu_x)_2-zMg_zAl_yO_[1+(3/2)y]H, an aluminate-based blue phosphor, wherein:

m is at least one divalent metal selected from the group consisting of Ba and Sr;

wherein

X is more than 0.05 and less than 0.5; and is

Y is more than or equal to 3 and less than or equal to 12; and is

Wherein H is a halogen selected from the group consisting of fluorine, chlorine, bromine, and iodine.

5. Has the formula (M)_1-xEu_x)_2-zMg_zAl_yO_[1+(3/2)y]H, an aluminate-based blue phosphor, wherein:

m is at least one divalent metal selected from the group consisting of Ba and Sr;

wherein

X is more than 0.2 and less than 0.5; and is

Y is more than or equal to 3 and less than or equal to 12; and is

Wherein H is a halogen selected from the group consisting of fluorine, chlorine, bromine, and iodine.

6. The blue phosphor of claim 5, wherein said phosphor is configured to absorb radiation having a wavelength in the range of about 280nm to 420nm and to emit visible light having a wavelength in the range of about 420nm to 560 nm.