Oxonitridoberyllosilicate phosphors

Abstract

The optionally substituted oxonitridoberyllosilicate photoluminescent compositions (i.e., phosphors) may be represented by the general formula AE 1-x-y-u A y+u Be 1-y-z-v B y+z+v S 1-z Al z O 1-v N 2+v :EU x ,Ce u It is expressed as where AE=Ba, Sr, Ca, Mg, A=Li, Na, K, Rb, 0≦x≦0.1, 0≦u≦0.1, 0<(x+u), 0≦y≦1, 0≦z≦1, (y+z+v)≦1, and (x+y+u)≦1. These phosphors are used in phosphor-converted LEDs, which may be advantageously used, for example, in lighting and display applications.

Description

[Technical Field]

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 287,797, filed December 9, 2021, which is incorporated herein by reference in its entirety.

[0002] This application relates generally to pcLEDs, pcLED arrays, light sources comprising pcLEDs or pcLED arrays, and displays comprising pcLED arrays. [Background technology]

[0003] Semiconductor light emitting diodes and laser diodes (collectively referred to herein as "LEDs") are among the most efficient light sources currently available. The emission spectrum of an LED typically has a single narrow peak at a wavelength determined by the device structure and the composition of the semiconductor materials from which it is constructed. By appropriate selection of device structure and material system, LEDs can be designed to operate at ultraviolet, visible, or infrared wavelengths.

[0004] LEDs may be combined with one or more wavelength-converting materials (collectively referred to herein as "phosphors") that absorb the light emitted by the LED and, in response, emit light at longer wavelengths. In such phosphor-converted LEDs ("pcLEDs"), the percentage of light emitted by the LED that is absorbed by the phosphor depends on the amount of phosphor material in the path of the light emitted by the LED, e.g., the concentration of the phosphor material in a phosphor layer disposed on or near the LED, and the thickness of the layer. Phosphor-converted LEDs may be designed so that all light emitted by the LED is absorbed by one or more phosphors, in which case the emission from the pcLED is entirely from the phosphor. In such cases, the phosphor may be selected, for example, to emit light in a narrow spectral range that cannot be efficiently produced directly by the LED. Alternatively, pcLEDs may be designed so that only a portion of the light emitted by the LED is absorbed by the phosphor, in which case the emission from the pcLED is a mixture of light emitted by the LED and light emitted by the phosphor. By appropriate selection of LEDs, phosphors, and phosphor compositions, such pcLEDs can be designed to emit, for example, white light having a desired color temperature and desired color rendering characteristics.

[0005] Technological and business applications of pcLEDs include their use in displays, matrices, and light engines. These include adaptive automotive headlights, augmented reality (AR) displays, virtual reality (VR) displays, mixed reality (MR) displays, displays for smart glasses and mobile phones, smartwatches, monitors and TVs, and flashlights for mobile phone cameras. Individual LED pixels in these architectures can have areas ranging from a few square millimeters to several square micrometers, depending on the size of the matrix or display and its pixel-per-inch requirements. LED matrices / displays can be realized, for example, by transfer of individual pixels from a donor substrate to a controller backplane or electronics board, or they can be formed via a monolithic approach. In the latter case, an array of monolithically integrated LED pixels is fabricated into an LED module on a donor epitaxial wafer, which is then transferred and attached to a controller backplane. Summary of the Invention [Problem to be solved by the invention]

[0006] Backlights for LCDs typically use pcLEDs with a combination of green and red phosphors. To achieve a wide color gamut, it is important to incorporate a green phosphor with as small a FWHM as possible. Eu-doped β-SiAlON is a green phosphor that has been widely applied in display technology. Another narrow-band green-emitting phosphor discussed for display applications is SrSi2O2N2:Eu.

[0007] Known problems with beta-SiAlON are low blue light absorption, limited by the low Eu concentration that can be incorporated by the lattice, concentration quenching at higher Eu concentrations, and emission reliability issues in the dark green spectral range. Other narrow-band green emitters, such as SrSi2O2N2:Eu, exhibit poor photothermal stability and poor reliability under application conditions. [Means for solving the problem]

[0008] The present application provides optionally substituted oxonitridoberyllosilicate photoluminescent compositions (i.e., phosphors) having the general formula AE 1-x-y-u A y+u Be 1-y-z-v B y+z+v Si 1-z Al z O 1-v N 2+v :EU x ,Ce u ; where AE=Ba, Sr, Ca, Mg, A = Li, Na, K, Rb, 0≦x≦0.1, 0≦u≦0.1, 0<(x+u), 0≦y≦1, 0≦z≦1, (y+z+v)≦1, and (x+y+u)≦1 A photoluminescent composition is disclosed, wherein:

[0009] Members of this phosphor family (e.g., Ba 1-x BeSiON2:Eu x ) may, for example, crystallize in an orthorhombic structure and may emit a narrow band of green light when excited, for example, with blue or shorter wavelength light. The peak emission may be in the range of 520 nm to 530 nm, with a full width at half maximum of, for example, 50 nm or less, or 45 nm or less. More typically, the peak emission may be in the range of, for example, 500 nm to 560 nm, with a full width at half maximum of, for example, 55 nm or less.

[0010] Substitution of Be with B (i.e., y+z+v>0) can result in a blue shift of the absorption and emission bands due to a decrease in the charge density of the O ligands surrounding the activator ions (Eu, Ce).

[0011] Combined doping of [B,Al] to [Be,Si] (ie, z>0) can improve the chemical stability of the host lattice.

[0012] Ce emits in the blue spectral range and can help improve the photostability of Eu(II) emission when added as a co-dopant (ie, x>0 and u>0).

[0013] Co-doping with monovalent alkali atoms (ie, y+u>0) can improve grain growth through the formation of reactive intermediates.

[0014] Examples of this family of phosphors include: Ba 0.9 Sr 0.05 K 0.015 Be 0.5 B 0.5 Si 0.5 Al 0.5 ON2:Eu 0.02 , Ce 0.015 ,Ba 0.48 Na 0.5 Be 0.5 B 0.5 SiON2:Eu 0.02 , Ba 0.5 Sr 0.49 Be 0.5 B 0.5 SiO 0.5 N 2.5 :EU 0.01 , Sr 0.99 BSiN3:Eu 0.01 Includes:

[0015] Another example of this family of phosphors is Ba 1-x BeSiON2:Eu x where, for example, 0 <x≦0.10、または0<x≦0.04、または0.005≦x≦0.02、またはx=0.005、またはx=0.0075、またはx=0.01、またはx=0.02である。

[0016] Also disclosed herein is a light emitting device, comprising a light emitting diode emitting primary light and, if necessary, a substituted oxonitridoberyllosilicate phosphor having the characteristics as described above, the phosphor being, for example, disposed in the optical path of light output from the light emitting diode, absorbing the primary light and responsively emitting secondary light having a wavelength longer than the primary light.

[0017] The phosphors and phosphor-converted LEDs disclosed herein may be used in a variety of devices and applications, such as those described in the Background section.

[0018] These and other embodiments, features and advantages of the present invention will become more apparent to those skilled in the art upon reference to the following more detailed description of the invention in conjunction with the accompanying drawings, which are first briefly described. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic cross-sectional view of an exemplary pcLED. [Figure 2A] FIG. 1 shows a cross-sectional view of an array of pcLEDs. [Figure 2B] FIG. 1 shows a schematic top view of an array of pcLEDs. [Figure 3A] FIG. 1 shows a schematic top view of an electronic board onto which an array of pcLEDs may be mounted. [Figure 3B] FIG. 3B is a similar view of an array of pcLEDs mounted on the electronics board of FIG. 3A. [Figure 4A] FIG. 1 shows a schematic cross-sectional view of an array of pcLEDs positioned relative to a waveguide and a projection lens. [Figure 4B] FIG. 4B shows an arrangement similar to that of FIG. 4A, but without the waveguide. [Figure 5] FIG. 1 is a schematic diagram illustrating an exemplary camera flash system having an adaptive lighting system. [Figure 6] FIG. 1 is a diagram illustrating an example display (e.g., AR / VR / MR) system having an adaptive lighting system. [Figure 7] FIG. 1 shows the crystal structure of BaBeSiON2. [Figure 8] FIG. 1 shows the XRD powder pattern (molybdenum radiation) measured for the material prepared in Example 1. [Figure 9] FIG. 1 shows the excitation spectrum (dashed line) and emission spectrum (solid line) of the material prepared in Example 1. [Figure 10] FIG. 1 shows the thermal quenching behavior of the material prepared in Example 1. [Figure 11] FIG. 1 shows the excitation (dashed lines) and emission (solid lines) spectra of a series of materials prepared in Example 2. [Figure 12] FIG. 1 shows the excitation spectrum (dashed line) and emission spectrum (solid line) of the material prepared in Example 3. [Figure 13] 1 shows the output spectrum of a white-emitting pcLED of Example 4 prepared by coating a blue LED with the green and red phosphors of Example 3. FIG. [Figure 14] FIG. 10 is a diagram showing the color gamut of the white-emitting pcLED of Example 4 displayed on the CIE 1931 chromaticity diagram. DETAILED DESCRIPTION OF THE INVENTION

[0020] The following detailed description should be read with reference to the drawings, in which like reference numerals represent like elements throughout the different drawings. The drawings, which are not necessarily to scale, depict selective embodiments and are not intended to limit the scope of the invention. The detailed description illustrates by way of example, and not by way of limitation, the principles of the invention.

[0021] 1 shows an example of an individual pcLED 100. It has a light emitting semiconductor diode (LED) structure 102 disposed on a substrate 104 and a phosphor layer 106 (also referred to herein as a wavelength conversion structure) disposed on the LED. The light emitting semiconductor diode structure 102 typically has an active region disposed between an n-type layer and a p-type layer. When an appropriate forward bias is applied to the diode structure, light is emitted from the active region. The wavelength of the emitted light is determined by the composition and structure of the active region.

[0022] The LED may be, for example, a III-nitride LED that emits ultraviolet, blue, green, or red light. LEDs formed from any other suitable material system and emitting light at any other suitable wavelength may also be used. Other suitable material systems may include, for example, III-phosphide materials, III-arsenide materials, and II-VI materials.

[0023] Any suitable phosphor material may be used depending on the desired light output and color specifications from the pcLED.

[0024] 2A-2B show cross-sectional and top views, respectively, of an array 200 of pcLEDs 100 having phosphor pixels 106 disposed on a substrate 202. Such an array may have any suitable number of pcLEDs arranged in any suitable manner. In the illustrated example, the array is shown as monolithically formed on a shared substrate, but an array of pcLEDs may alternatively be formed from separate individual pcLEDs. The substrate 202 may optionally include CMOS circuitry for driving the LEDs and may be formed from any suitable material.

[0025] 2A-2B show a 3x3 array of nine pcLEDs, but such an array may have, for example, tens, hundreds, or thousands of LEDs. Individual LEDs (pixels) may have a width (e.g., side length) in the plane of the array of, for example, 1 millimeter (mm) or less, 500 microns or less, 100 microns or less, or 50 microns or less. LEDs in such an array may be spaced apart from one another by streets or lanes having widths in the plane of the array of, for example, several hundred microns, 100 microns or less, 50 microns or less, 10 microns or less, or 5 microns or less. While the illustrated example shows rectangular pixels arranged in a symmetrical matrix, the pixels and array may have any suitable shape or arrangement.

[0026] LEDs with an in-plane dimension (e.g., side length) of the array of about 50 microns or less are typically referred to as micro LEDs, and an array of such micro LEDs may be referred to as a micro LED array.

[0027] An array of LEDs, or a portion of such an array, may be formed as a segmented monolithic structure, with individual LED pixels electrically isolated from one another by trenches and / or insulating materials, but the electrically isolated segments remaining physically connected to one another by portions of the semiconductor structure.

[0028] Individual LEDs in an LED array may be individually addressable, addressable as part of a group or subset of pixels in the array, or non-addressable. Light-emitting pixel arrays are therefore useful for any application requiring or benefiting from fine intensity, spatial, and temporal control of light distribution. These applications may include, but are not limited to, highly precise, specialized patterns of light emitted from pixel blocks or individual pixels. Depending on the application, the emitted light may be spectrally distinct, adaptive over time, and / or environmentally responsive. Such light-emitting pixel arrays may provide preprogrammed light distributions in spatial or temporal patterns of varying intensity. The emitted light may be based at least in part on received sensor data and may be used for optical wireless communication. The associated electronics and optics may be separate at the pixel, pixel block, or device level.

[0029] 3A-3B, the pcLED array 200 may be mounted on an electronics board 300, which may include a power and control module 302, a sensor module 304, and an LED mounting area 306. The power and control module 302 may receive power and control signals from an external source and may receive signals from the sensor module 304, based on which the power and control module 302 controls the operation of the LEDs. The sensor module 304 may receive signals from any suitable sensor, such as a temperature sensor or a light sensor. Alternatively, the pcLED array 200 may be mounted on a separate board (not shown) from the power and control module and the sensor module.

[0030] Individual pcLEDs may incorporate or be combined with lenses or other optical elements, if desired, disposed adjacent to or above the phosphor layer. While not shown, such optical elements may be referred to as "primary optics." Also, as shown in FIGS. 4A-4B , the pcLED array 200 (e.g., mounted on an electronics board 300) may be combined with secondary optical elements, such as a waveguide, a lens, or both, for use in an intended application. In FIG. 4A , light emitted by the pcLEDs 100 is collected by a waveguide 402 and directed to a projection lens 404. The projection lens 404 may be, for example, a Fresnel lens. This arrangement is suitable for use in, for example, an automobile headlight. In FIG. 4B , light emitted by the pcLEDs 100 is collected directly by the projection lens 404 without the use of an intervening waveguide. This arrangement is particularly suitable when the pcLEDs are spaced sufficiently close to each other and may be used in camera flash applications in addition to automobile headlights. In a micro LED display application, for example, an optical arrangement similar to that shown in Figures 4A-4B may be used. In general, any suitable arrangement of optical elements may be used in combination with the LED arrays described herein, depending on the desired application.

[0031] Arrays of independently operable LEDs may be used in combination with lenses, lens systems, or other optical systems (e.g., as described above) to provide illumination that can be adapted for a particular purpose. For example, during operation, such adaptive lighting systems may provide illumination that varies in color and / or intensity across an illuminated scene or object and / or is aimed in a desired direction. A controller may be configured to receive data representing the placement and color characteristics of objects or people in a scene and, based on that information, control the LEDs in the LED array to provide illumination adapted to the scene. Such data can be provided, for example, by an image sensor or optical (e.g., laser scanning) or non-optical (e.g., millimeter radar) sensor. Such adaptive lighting is becoming increasingly important for automotive, mobile device camera, VR, and AR applications.

[0032] 5 schematically illustrates an exemplary camera flash system 500 that includes an LED array and lens system 502, which may be similar or identical to the systems described above. The flash system 500 also includes an LED driver 506, which is controlled by a controller 504, such as a microprocessor. The controller 504 is also coupled to a camera 507 and a sensor 508, and may operate according to instructions and profiles stored in a memory 510. The camera 507 and adaptive lighting system 502 may be controlled by the controller 504, and their fields of view may be aligned.

[0033] The sensors 508 may include, for example, position sensors (e.g., gyroscopes and / or accelerometers) and / or other sensors, which may be used to determine the position, velocity, and orientation of the system 500. Signals from the sensors 508 may be provided to the controller 504 and used to determine a preferred course of action for the controller 504 (e.g., which LEDs are currently illuminating the target and which LEDs will illuminate the target after a predetermined time).

[0034] In operation, illumination from some or all of the pixels of the LED array may be adjusted, deactivated, operated at full intensity, or operated at intermediate intensities, at 502. Beam focusing or steering of the light emitted by the LED array, at 502, is performed electronically by activating one or more subsets of the pixels, allowing dynamic adjustment of the beam shape without moving optics within the lighting device or changing the focus of lenses.

[0035] 6 schematically illustrates an exemplary display (e.g., AR / VR / MR) system 600. The system includes an adaptive light emitting array 610, a display 620, a light emitting array controller 630, a sensor system 640, and a system controller 650. Control inputs are provided to the sensor system 640, and power and user data inputs are provided to the system controller 650. In some embodiments, the modules included in the system 600 may be compactly arranged in a single structure, or one or more elements may be separately mounted and connected via wireless or wired communication. For example, the light emitting array 610, the display 620, and the sensor system 640 may be mounted in a headset or glasses, and the light emitting controller and / or the system controller 650 may be separately mounted.

[0036] The light emitting array 610 may include one or more adaptive light emitting arrays as described above, for example, used to project light in graphical or object patterns to support AR / VR / MR systems. In some embodiments, an array of micro LEDs may be used.

[0037] System 600 can incorporate a wide range of optical elements in adaptive light emitting array 610 and / or display 620 , for example, light emitted by adaptive light emitting array 610 may be coupled into display 620 .

[0038] The sensor system 640 may include external sensors, such as a camera, depth sensor, or audio sensor, to monitor the environment, and internal sensors, such as an accelerometer or two- or three-axis gyroscope, to monitor the AR / VR / MR headset position. Other sensors may include, but are not limited to, air pressure, stress sensors, temperature sensors, or any other suitable sensors necessary for local or remote environmental monitoring. In some embodiments, the control input may include detected touch or tap, gesture input, or control based on headset or display position.

[0039] In response to data from the sensor system 640, the system controller 650 can send images or instructions to the light emitting array controller 630. Changes or modifications to the images or instructions can also be made by user data input or automatic data entry, as needed. User data input may include, but is not limited to, voice commands, tactile feedback, eye or pupil placement, or provided by a connected keyboard, mouse, or game controller.

[0040] As previously mentioned, the present application discloses optionally substituted oxonitridoberyllosilicate phosphors, which have the general formula AE 1-x-y-u A y+u Be 1-y-z-v B y+z+v Si 1-z Al z O 1-v N 2+v :EU x ,Ce uwhere AE = Ba, Sr, Ca, Mg; A = Li, Na, K, Rb; 0≦x≦0.1; 0≦u≦0.1; 0<(x+u); 0≦y≦1; 0≦z≦1; (y+z+v)≦1; and (x+y+u)≦1. These phosphors exhibit peak photoluminescent emission, for example, from 500 nm to 600 nm or 520 nm to 530 nm, with a FWHA of, for example, ≦55 nm, ≦50 nm, or ≦45 nm. These phosphors may be used, for example, in pcLEDs used in displays and lighting.

[0041] The oxonitridoberyllosilicate phosphor BaBeSiON2 crystallizes in the orthorhombic space group Ama2 (no. 40) with lattice parameters a = 5.6366(3), b = 11.6363(7), and c = 4.9295(3). Figure 7 shows its crystal structure. Ba atoms are shown as gray spheres, [BeN3] units are shown as black triangles, and [SiON3] units are shown as gray tetrahedra.

[0042] The crystal structure is closely related to oxonitridosilicates of the AE[Si2O2N2] type, especially BaSi2O2N2. BaBeSiON2 is a condensed trigonal planar [BeN3] 7- Unit and [SiON3] 7- [BeSiON2] constructed by alternating chains of tetrahedra 2- The layers show the hexahedral chains exhibiting strictly alternating UDU... sequences. [SiON3] within each other BaSi2O2N2 7- The tetrahedron is [BeN3] in BaBeSiON2. 7- Replaced by the unit.

[0043] The barium ions in BaBeSiON2 are 2 ] 2- It is found between the layers and is coordinated seven times by four O atoms and three N atoms, forming a distorted pentagonal bipyramid.

[0044] Table 1 below provides the crystallographic data for BaBeSiON2.

[0045] [Table 1] Table 2 below provides the atomic coordinates and equivalent substitution parameters for BaBeSiON2.

[0046] [Table 2] Table 3 below provides selected bond lengths (Å) for BaBeSiON2.

[0047] [Table 3] The synthesis and properties of one example of an optionally substituted oxonitridoberyllosilicate phosphor as described above are given below.

[0048] Example 1 Ba 0.995 BeSiON2:Eu 0.005 50.8 mg of barium amide prepared from barium metal (Alfa Aesar, 99.9%) by the ammonothermal method, 5.5 mg of beryllium nitride (ABCR, 99%) prepared by firing beryllium metal (ABCR, 99%) in a nitrogen atmosphere, 4.2 mg of silicon (Alfa Aesar, 99.9%), 9.0 mg of silicon oxide, and 0.3 mg of europium fluoride (Sigma-Aldrich) were mixed in an agate mortar and fired in a high-frequency furnace at a set temperature of 1400°C for 5 hours in a nitrogen atmosphere.

[0049] Figure 8 shows the XRD powder pattern of Example 1. This is crystallized in the orthorhombic structure of BaBeSiON2 with lattice constants a0 = 5.6366 Å, b0 = 11.6363 Å, and c0 = 4.9295 Å. Figure 9 shows the excitation spectrum (dashed line, monitoring at 530 nm) and emission spectrum (solid line, excitation at 440 nm) of Example 1. When this material is excited with blue light at 440 nm, it shows peak emission at 522 nm and the emission full-width at half-maximum is 45 nm. Figure 10 shows the thermal quenching behavior of Example 1 between 6 K and 550 K.

[0050] The elemental composition of BaBeSiON2 was confirmed by energy-dispersive X-ray spectroscopy (EDS). Table 4 shows the elemental analysis results of BaBeSiON2 in atomic%. Note that it is necessary to pay attention that Be cannot be detected by EDS.

[0051]

Table 4

[0052] Figure 11 shows the excitation spectrum (dashed line, 530 nm monitoring) and emission spectrum (solid line, 440 nm monitoring) for the series of materials prepared in Example 2. Powders with a range of doping concentrations exhibit peak emission ranges from 522 to 528 nm when excited with 440 nm blue light, with FWHMs ranging from 45 to 54 nm.

[0053] Example 3 Ba 0.9925 BeSiON2:Eu 0.0075 Synthesis of 83.6 mg of barium hydride (Materion, 99.5%), 15.0 mg of beryllium oxide (Alfa Aesar, 99.95%), 28.1 mg of silicon nitride (Ube Industries, SN-E10), 0.9 mg of europium fluoride (Sigma-Aldrich), and 1.3 mg of barium fluoride (abcr, 99.999%) were mixed in an agate mortar and fired in a high-frequency furnace at a set temperature of 1400°C for 5 hours under a nitrogen atmosphere.

[0054] Figure 12 shows the excitation spectrum (dashed line, 538 nm monitoring) and emission spectrum (solid line, 420 nm excitation) of Example 3. A Eu doping level of ∼0.75% results in narrow band green emission with a FWHM of 46 nm with an emission maximum at ∼522 nm.

[0055] Example 4 Ba 0.9925 BeSiON2:Eu 0.0075 pcLED with The green phosphor of Example 3 (Ba 0.9925 BeSiON2:Eu 0.0075 ) and red-emitting KSIF:Mn (K2SiF6:Mn 4+) was coated onto a blue LED to fabricate a white-emitting pcLED. Figure 13 shows its output spectrum. Figure 14 shows the color gamut (solid line - FOS) of this white pcLED displayed on the CIE 1931 chromaticity diagram and compared to the DCI P3 color gamut. The displayed color gamut achieves 108.3% compared to the NTSC standard and 109.0% compared to the DCI P3 color gamut.

[0056] Example 5 Ba 0.9925 BeSiON2:Eu 0.0075 Synthesis of 83.6 mg of barium hydride (Materion, 99.5%), 15.0 mg of beryllium oxide (Alfa Aesar, 99.95%), 28.1 mg of silicon nitride (Ube Industries, SN-E10), 0.9 mg of europium fluoride (Sigma-Aldrich), 1.3 mg of barium fluoride (abcr, 99.999%), and 1.4 mg of LiN (Materion, 99.5%) were mixed in an agate mortar and fired in a high-frequency furnace at a set temperature of 1375°C under a nitrogen atmosphere for 3 hours. The addition of LiN has been observed to shorten the firing time and improve the phase formation and crystallization of the target compound.

[0057] The present disclosure is illustrative and not limiting. Other modifications will be apparent to those skilled in the art in light of the present disclosure, and such modifications are intended to be included within the scope of the appended claims.

Claims

1. 1. A photoluminescent composition comprising: AE 1－x－y－u A y＋u Drink 1－y－z－v B y＋z＋v And 1－z the z A 1－v N 2+v :I x ,What u ; where AE = Ba, Sr, Ca, Mg, A = Li, Na, K, Rb, 0≦x≦0.1、 0≦u≦0.1、 0<(x+u), 0≦y＜1、 0≦z＜1、 0≦v＜1、 (y + z + v) < 1 and (x + y + u) ≤ 1 1. A photoluminescent composition comprising:

2. 2. The photoluminescent composition of claim 1, wherein (y+z+v)>0.

3. 3. The photoluminescent composition of claim 2, wherein z>0.

4. 2. The photoluminescent composition of claim 1, wherein x>0 and u>0.

5. 2. The photoluminescent composition of claim 1, wherein (y+u)>0.

6. Ba 0.9 Sr 0.05 K 0.015 Be 0.5 B 0.5 Si 0.5 Al 0.5 ON 2 :EU 0.02 , Ce 0.015 10. The photoluminescent composition of claim 1, characterized by:

7. Ba 0.48 Na 0.5 Be 0.5 B 0.5 SiON 2 :EU 0.02 10. The photoluminescent composition of claim 1, characterized by:

8. Ba 0.5 Sr 0.49 Be 0.5 B 0.5 SiO 0.5 N 2.5 :EU 0.01 10. The photoluminescent composition of claim 1, characterized by:

9. Ba 1－x BeSiON 2 :EU x , and 0＜x≦0.10 10. The photoluminescent composition of claim 1, characterized by:

10. 10. The photoluminescent composition of claim 9, wherein 0<x≦0.

04.

11. 10. The photoluminescent composition of claim 9, wherein 0.005≦x≦0.

02.

12. 10. The photoluminescent composition of claim 9, wherein x=0.

01.

13. 10. The photoluminescent composition of claim 9, wherein x=0.

005.

14. 10. The photoluminescent composition of claim 9, wherein x=0.0075.

Images