WO2016094863A1

WO2016094863A1 - Nitride phosphor element for light emitting diodes

Info

Publication number: WO2016094863A1
Application number: PCT/US2015/065379
Authority: WO
Inventors: Hiroaki Miyagawa; James Chienchung Shih
Original assignee: Nitto Denko Corporation
Priority date: 2014-12-11
Filing date: 2015-12-11
Publication date: 2016-06-16

Abstract

Described herein is a method for making a phosphor ceramic element. Also described herein are ceramic elements including a phosphor having the following formula: (Eu_xCa_1-x)_m/2Si_12-(m+n)AL_m+nO_nN_16-n, Formula 1, wherein 0.001≤x≤0.25, 0.001≤m≤7, and 0.001≤n≤5.

Description

NITRIDE PHOSPHOR ELEMENT FOR LIGHT EMITTING DIODES

Inventors:

Hiroaki Miyagawa and James C. Shih BACKGROUND

Field of Invention

[0001] Some embodiments relate to light emitting diodes. Specifically, some embodiments relate to phosphors such as oxynitride phosphors activated by a rare earth element. Furthermore, some embodiments relate to a Ca-a-SiAION compound activated by Eu³⁺.

Description of Related Art

[0002] Light Emitting Diode (LED) based lighting has been attractive technology for future lighting development due to longer operational lives of LEDs in comparison to incandescent lamps. For LEDs, phosphor plates outperform phosphor powders in high intensity lighting applications. For white-light applications, the preferred light source is a blue LED driving white-light luminescence. In addition, over thousands of years, people have developed a preference towards warm white light for indoor lighting instead of cool colors. As a result, there is a need for phosphors activated by blue LEDs which will result in the generation of warm-white lighting.

[0003] White light-emitting devices may be fabricated using a combination of a blue light-emitting diode (LED) and a phosphor material. These devices are often configured so that the blue light from the blue light-emitting diode comes in contact with the phosphor material so that the phosphor material may absorb a portion of the blue light and emit light that is of a longer wavelength. As a result, these materials have been described as wavelength converting or color changing. This allows the device to emit a combination of light that appears more white. There are two common methods for doing so. First, the phosphor particles may be dispersed in another solid component through which the light passes, thus coming into contact with the dispersed phosphor particles. Second, the phosphor material may be in the form of a phosphor ceramic compact, in which case the blue light would pass through the compact.

[0004] The disadvantage of the phosphor particles is that particles that are large enough to be emissive have a tendency to scatter the light, thus reducing the light emission of the device. On the other hand, the phosphor ceramic compacts are generally prepared by sintering under conditions that may affect the luminescent efficiency and/or other physical characteristics of the phosphor ceramic. Furthermore, the conventional atmospheric conditions for sintering of phosphor materials are usually under a vacuum, which may require more instrumentation to provide the desired level of vacuum, increasing the overall manufacturing costs. Thus, there is a need for a translucent phosphor ceramic compact with improved luminescence that can be manufactured without the need of vacuum conditions.

[0005] SiAION phosphor powders have been described for use in white light generating devices. Some SiAION materials can be alpha SiAION (a-SiAION) compounds or beta SiAION (β-SiAION) compounds. Europium (Eu) doped a-SiAION materials can emit an orange light (between about 570 nm to about 610 nm, e.g., about 590 nm). In contrast, Eu-doped β-SiAION materials can emit a more yellow light (between about 500 to about 570 nm). A light emitting device having a blue emitter and an orange translucent ceramic could provide a warm light device. Thus, there is a need for a translucent phosphor SiAION phosphor ceramic comprising primarily an a-SiAION phosphor.

SUMMARY

[0006] The present embodiments include a method for making a nitride phosphor ceramic element for use in LED applications.

[0007] Some embodiments include a method of preparing a nitride phosphor ceramic element comprising: heating a green form between about 400 °C to about 1000 °C for a period of about 30 minutes to about 36 hours to provide a brown form; and pressureless sintering the brown form at a temperature in a range of about 1500 °C to about 1900 °C for a time period between about 3 hours to about 48 hours.

[0008] Some embodiments include a method for making a nitride phosphor ceramic comprising: mixing at least one precursor in a dispersant slurry; tape casting the dispersant slurry to provide a green form; debinding the green form at temperatures between about 400 °C to about 1000 °C for a period of time between about 30 minutes to about 36 hours to provide a brown form; and pressureless sintering the brown form at a temperature between about 1500 °C and about 1900 °C for a time period between about 3 hours to about 48 hours. In some embodiments, the method further comprises bisque-firing the brown form at a temperature between 800 °C to about 1400 °C for about 30 minutes to about 4 hours. In some embodiments, the method further comprises adding a sintering aid to the dispersant slurry. In some embodiments, the method further comprises cold- isostatic pressing (CIP) the green form at between about 30 MPa to about 60 MPa for about 5 minutes to about 2 hours. In some embodiments, the method further comprises hot-isostatic pressing (HIP) the sintered brown form at about 100 MPa to about 1000 MPa at between 1600 °C and 1750 °C for about 30 minutes to about 6 hours.

[0009] Some embodiments include a nitride phosphor ceramic element that can be made by the method described above. In some embodiments, the element comprises at least a phosphor, whose emissive peak wavelength is between about 580 nm to about 620 nm. In some embodiments, where the phosphor can be defined by the following chemical formula: (EUxCa_{1 -x})_m/2Sii2-m- _nAl_m+nOnNi6-n, wherein 0.001 <x<0.25, 0.001 <m<7, 0.001 <n<5. In some embodiments, the phosphor can comprise at least one of the following: (Eu₀.i 5Cao.85)o.75Si9.3Al2.70i.₂Ni4.8 [Composition #1 (Comp-1 )];

(Eu₀.i5Cao.85)i .oSi8.8Al3.20i.₂Ni4.8 [CoiTip-2]; (Eu₀.o75Cao.925)i .oSi8.8Al3.20i .₂Ni4.8 [Comp-

3]; (EUo.i5Cao.85)2.oSi5.₇Al6.302.₃Nl3.7 [Comp-4]; (EUo.ioCao.9o)3.oSi2.6Al9.₄0₃.₄Ni2.6

[Comp-5]; (Eu₀.ioCao.9o)3.oSii .eAlio.20₄.2Ni i .8 [Comp-6];

(Euo.i 5Cao.85)2.oSi5.₂Al6.₈02.8 i 3.2 [CoiTip-7]; (Eu₀.o75Cao.925)i .oSi8.6Al3.40i.₄Ni4.6 [Comp- 8]; (Euo.o75Cao.925)i .oSi9.oAI₃.oOi .oNi5.o [Comp-9]; (Euo.isCao.eskoSig.oAkoOi .oNis.o [Comp-10]; (Eu₀.o75Cao.925)i .oSi8.3Al3.70i.₇Ni4.3 [Comp-1 1 ]; (Euo.o75Cao.925)i .oSi_B.4Al3.eOi .eNi4.4 [Comp-12];

.sNuj [Comp-13];

.sN .s [Comp-14];

(Euo.o5Cao.95)i .25Si₇.₇5AI₄.250i .₇₅Ni₄.25 [CoiTip-15]; (Euo.osCao 95)l .25Si .5AI₄.502.o l₄.o [Comp-16]. In some embodiments, the phosphor comprises at least

(EUo.075Ca₀.925)l .oSi8.6AI₃.40l .4Nl4.6 [Comp-8] and/Or (EUo.075Ca₀.925)l .oSi8.3AI₃.70l .7Nl4.3

[Comp-1 1 ]. In some embodiments, the phosphor is a crystalline phosphor. In other embodiments, the phosphor is a polycrystalline phosphor. In some embodiments, the ceramic element can further comprise a sintering aid. In some embodiments, the sintering aid can comprise MgO and/or CaO. In some embodiments, the nitride phosphor ceramic element can be characterized as having a transmittance of more than 20 T_t% at 800 nm light wavelength.

[0010] Some embodiments include a nitride phosphor ceramic element, which is not restricted to being made by the methods described herein. In some embodiments, the nitride phosphor comprises at least a phosphor whose emissive peak wavelength is between about 580 nm to about 620 nm.

[0011] Some embodiments include a ceramic element comprising a phosphor of Formula 1 :

(Eu_xCai-x)_m/2Sii2-m-nAl_m+nO_nNi6-n wherein x is between about 0.001 and about 0.25, m is between about 0.001 and about 7, and n is between about 0.001 and about 5.

[0012] In some embodiments, the phosphor can comprise at least one of the following: (Eu₀.o75Cao.925)i .oSi8.6Al3.40i .₄Ni4.6 [Comp-8];

(EUo.0 5Cao.925)l .oSi8.₃Al3. 0l .₇Ni4.3 [COITip-1 1 ]; (EUo.075Ca₀.925)l .oSi_B.4 AI3.6 Ο1.6 N14.4

[Comp-12];

Sis.o AU.o Oi .s N14.5 [Comp-14]; (Euo.o5Ca₀.95)i .25 Si₇.75 AI4.25 Ο1.75 N14.25 [Comp-15]; (Eu₀.o5Ca₀.95)i .25 Si_{7 5} AI4.5 O_{2 0} N14.0 [Comp-16]. In some embodiments, the phosphor comprises at least (Eu₀.o75Ca₀.925)i .oSi8.6 AI3.4O1.4N14.6 [Comp-8] and/or (Eu₀.o75Cao.925)i .oSi8.3Al3.70i .₇Ni4.3 [Comp-1 1 ]. In some embodiments, the phosphor comprises a crystalline phosphor. In other embodiments, the phosphor comprises a polycrystalline phosphor. In some embodiments, the element further comprises a sintering aid. In some embodiments, the sintering aid can be at least MgO or CaO. In some embodiments, the nitride phosphor ceramic element can be characterized as having a transmittance of more than 20 T_t% at 800 nm light wavelength.

[0013] In some embodiments, a lighting device is also described; where the lighting device can comprise either aforementioned ceramic elements or a combination thereof, applied directly as a layer on an LED. In some embodiments, the LED is a blue LED. In some embodiments, the phosphor element emits orange light, wherein the lighting device provides a soft white light.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1 is one possible embodiment of the process for making the nitride phosphor ceramic element.

[0015] FIG. 2 is a plot showing the Transmittance and Internal Quantum Efficiency of Examples 1 through 4 before Hot Isostatic Pressing (HIP) treatment at 1875°C.

[0016] FIG. 3 is a plot showing the Transmittance and Internal Quantum Efficiency of Examples 2 through 4 after HIP treatment at 1875°C.

[0017] FIG. 4 is a plot showing the Transmittance and Internal Quantum Efficiency of Examples 2 through 1 1 before HIP treatment at 1675°C.

[0018] FIG. 5 is a plot showing the Transmittance and Internal Quantum Efficiency of Examples 3 through 1 1 after HIP treatment at 1675°C.

[0019] FIG. 6 is a plot presenting the chromaticities of LED-1 through LED- 7 plotted on an International Commission on Illumination (CIE) 1931 X-Y plot.

[0020] FIG. 7 is a plot presenting the plug-in efficiencies versus input current for LED-1 and LED-2.

[0021] FIG. 8 is a plot presenting the plug-in efficiencies versus input current for LED-3 and LED-5. [0022] FIG. 9 is a plot presenting the plug-in efficiencies versus input current for LED-6 and LED-7.

DETAILED DESCRIPTION

[0023] As used herein, the term "variant" refers to different compounds which can satisfy the chemical equation dictated in Formula 1 so long as the variables pertaining to the chemical ratios (e.g. x, m, and n) are within the stated limits.

[0024] As used herein, the terms "green form" and/or "brown form" refer to the physical form of the ceramic element after a specific stage in its manufacturing method. This nomenclature does not in any way limit the applicable materials under this disclosure to only compositions that appear to be green or brown. The terms "green" and "brown" have the ordinary meaning known to a person of ordinary skill in the art as related to the processes of debinding and sintering.

[0025] Some embodiments include a method for making a nitride phosphor ceramic element. In some embodiments, the method can comprise mixing at least one precursor in a dispersant solution to provide a dispersant mixture that can be a solution or suspension. In some embodiments, the suspension is a dispersant slurry. In some embodiments, the precursors can be a carbonate, oxide and/or nitride. In some embodiments, the carbonate, oxide and/or nitride can comprise the desired chemical element, e.g., Ca, Si, Al, O, N and/or Eu to form a Ca-a-SiAION- based phosphor. In some embodiments, the precursors can comprise: CaC0₃, Si₃N₄, AIN, and/or Al₂0₃. In some embodiments, the dispersant mixture can further comprise the precursor Eu₂0₃, as a dopant.

[0026] In some embodiments, the method can comprise adding one or more sintering aids to the dispersant mixture. In other embodiments, one or more sintering aids can be formed as an intermediate, by-product and/or end product from reactions among the precursors. In some embodiments, the one or more sintering aids can be directly added to the dispersant mixture. In some embodiments, one or more sintering aids are added to the dispersant mixture in addition to one or more sintering aids formed as the result of precursor interactions. In some embodiments, CaO can be formed from the dispersant precursors.

[0027] In some embodiments, the method can comprise tape casting the dispersant mixture or slurry to provide a green form. The tape casting process can be conducted in order to provide accurate thickness control of the sintered phosphor ceramic. In some embodiments, the slurry can then be cast on a releasing substrate (e.g., a silicone coated polyethylene teraphthalate substrate) to form a tape. For example, the slurry may be cast onto a moving carrier using a doctor blade and dried to form a tape. The thickness of the cast tape can be adjusted by changing the gap between the doctor blade and the moving carrier. In some embodiments, the gap between the doctor blade and the moving carrier is in the range of about 0.125 mm to about 1 .25 mm, about 0.15 mm to about 0.75 mm, or about 0.2 mm to about 0.4 mm. Meanwhile, the speed of the moving carrier can have a rate in the range of about 10 cm/min to about 150 cm/min, between about 20 cm/min and about 50 cm/min, or between about 20 cm/min and about 40 cm/min. By adjusting the moving carrier speed and the gap between the doctor blade and moving carrier, the tape is expected to have a thickness between about 20 μιη and about 300 μιη. In some embodiments, the tapes may be optionally cut into desired shapes after tape casting.

[0028] In some embodiments, after tape casting, the green form then undergoes a cold-isostatic press (CIP) process. In some embodiments, the CIP process comprises heating the samples to between about 70 °C to about 100 °C at an isostatic pressure of between about 30 MPa to about 60 MPa lasting in duration from about 5 minutes to 2 hours. In some embodiments, the CIP comprises heating the green forms to about 85 °C at a pressure of about 42 MPa for about 10 minutes.

[0029] Some methods can comprise tape casting the dispersant mixture or slurry to provide a green form. In some embodiments, the tape-cast green forms then undergo debinding in air atmosphere at temperatures that can range from about 400 °C to about 1000 °C for a timeframe appropriately ranging from about 30 minutes to about 36 hours in an oven. Debinding can provide the burning off of any binding additives in the green form prior to sintering. In some embodiments, debinding comprises heating in an oven between about 600 °C to about 800 °C. In some embodiments, the mixture is debinded at about 700 °C in air for about 3 hours. The result of debinding is a brown form.

[0030] In some embodiments, after debinding, the brown form may then be bisque-fired at a temperature that can range from about 800 °C to about 1400 °C at a time that can appropriately range from about 30 minutes to about 4 hours. In some embodiments, the method comprises bisque firing the brown form at temperatures of between 800 °C to about 1400 °C or between about 1000 °C to about 1300 °C. In some embodiments, bisque firing is done for about 2 hours to about 3 hours. In some embodiments, bisque firing is done at about 1200 °C for about 2 hours. In some embodiments, the bisque firing is performed under a reducing atmosphere. In some embodiments, the reducing atmosphere can be an atmosphere of mixed gases of nitrogen gas (N₂) and hydrogen gas (H₂). In some embodiments, the atmosphere can comprise a 97% N₂ / 3% H₂ atmosphere. The bisque firing can impart material strength to the material in order to facilitate handling in subsequent manufacturing operations.

[0031] After debinding (or optionally bisque firing), the brown form, or the product of debinding, may be subject to pressureless sintering. Sintering may occur at any suitable temperature, such as about 1500-1900 °C, about 1600-1800 °C, about 1600-1700 °C, about 1650-1700 °C, about 1700-1800 °C, about 1625 °C, about 1650 °C, about 1675 °C, about 1700 °C, about 1725 °C, about 1750 °C, or any temperature in a range bounded by any of these values.

[0032] Sintering may be carried out for any suitable amount of time, such as about 3-48 hours (h), about 4-30 h, about 4-10 h, about 10-20 h, about 20-30 h, about 8 h, about 16 h, about 24 h, or any time in a range bounded by any of these values.

[0033] Pressureless sintering can be the sintering of a green form or brown form or compact without applied pressure, e.g., mechanical pressure. While not wanting to be limited to any particular theory, unlike methods that also utilize pressure from a mold or surrounding gas to form the ceramic, such as in hot-press methods, sintering is done primarily using temperature to transform the material without the assistance of external forces applied directly to the material.

[0034] In some embodiments, sintering is carried out at a temperature between or greater than about 1500 °C and but less than about 1900 °C for a time period of 3 hours to about 48 hours. In some embodiments the duration can be between about 6 hours to about 24 hours.

[0035] In some embodiments, pressureless sintering can be performed at less than 10 MPa, less than 5 MPa, less than 1 MPa, less than 0.5 MPa, and or less than 0.25 MPa. In some embodiments, the sintering can be performed at atmospheric pressure. In some embodiments, the sintering can be performed at about 0.1 MPa. In some embodiments, the sintering excludes the application of mechanical force to the ceramic body or green sheet being sintered.

[0036] In some embodiments, sintering the brown form, including pressureless sintering, can be done at a temperature greater than 1500 °C, 1550 °C, 1600 °C, or 1650 °C and less than about 1700 °C, 1725 °C, 1750 °C, 1760 °C, 1775 °C, 1780 °C, 1790 °C, 1800 °C, 1875 °C, or 1900 °C. While not wanting to be limited by theory, it is believed that increased sintering temperatures, e.g., those at and/or exceeding about 1750 °C, can increase the amount or vol% of β-SiAION present in the resulting end-product or element. In some embodiments, the pressureless sintering can range in duration from about 3 hours to about 48 hours or about 6 to about 24 hours. In some embodiments, the pressureless sintering can be performed between about 1625 °C and about 1750 °C for durations about 24 hours to about 8 hours. In general, sintering transforms the brown form into a ceramic preform. In some embodiments, before pressureless sintering, the brown form can be embedded in a sacrificial packing powder in order to prevent its material from being partially reduced to constituent metals due to a strong reducing atmosphere during the sintering process.

[0037] After sintering, the ceramic plate, or sintered brown form, may be allowed to cool to room temperature. In some embodiments, the cooling may be controlled. For example, cooling may be controlled to occur at a rate of about 5-20 °C/min, about 5-10 °C/min, about 10-15 °C/min, about 10 °C/min, or at any rate in a range bounded by any of these values.

[0038] In some embodiments, after sintering, the method can further comprise Hot Isostatic Pressing (HIP) the Ca-a-SiAION ceramic preform.

[0039] HIP may be carried out at any suitable temperature such as in a range of about 1600-1750 °C, about 1650-1700 °C, about 1675 °C, about 1875 °C, or any temperature in a range bounded by any of these values.

[0040] HIP may be carried out at any suitable pressure such as in a range of about 15-70 MPa, about 20-40 MPa, about 30-50 MPa, about 35 MPa, or at any pressure in a range bounded by any of these values.

[0041] HIP may be carried out for any suitable amount of time, such as in a range of about 10-120 min, about 30-100 min, about 40-80 min, about 1 hr, or any time in a range bounded by any of these values.

[0042] In some embodiments, HIP is carried out under an inert gas, such as N₂.

[0043] In some embodiments, HIP is carried out at a pressure that can range from about 10 MPa to about 1000 MPa at a temperature between about 1600 °C and about 1900 °C in order to remove the porosity. In some embodiments, HIP is done at about 1875 °C or about 1675 °C. In some embodiments, the HIP is done at a pressure ranging from about 20 MPa to about 60 MPa or about 35 MPa. In some embodiments, the duration of HIP can range from about 30 minutes to about 6 hours. In some embodiments the duration of HIP is about 1 hour. The result is a Ca- a-SiAION nitride ceramic.

[0044] A distinction from other methods of creating Ca-a-SiAION ceramics is that the precursors uniquely exist after tape casting are formed into Ca-a-SiAION during the subsequent processes while the element is already tape cast into its final form. This process presents an improvement to other processes where the a-SiAION is first formed as a powder and then tape cast by reducing the overall manufacturing steps. While not wanting to be limited to any particular theory, this methodology is also distinguished from pressureless sintering of oxide ceramics, due to the unique problems associate with nitrides which are addressed in the aforementioned methodology.

[0045] In addition, some embodiments include a nitride phosphor ceramic comprising a phosphor having the following formula:

(Eu_xCai_-x)_m/₂Sii2-(m₊n)Al_m+nOnNi6-n, Formula 1 , wherein 0.001 <x<0.25, 0.001 <m<7, 0.001 <n<5. The x value describes the amounts of Eu scintillator, m relates to the Al concentration and n reflects the oxygen concentration. In some embodiments, the ceramic element when exposed to a blue LED emits orange light with a peak wavelength of between about 580 nm to about 620 nm. In some embodiments, the phosphor variants can be: (Eu₀.i 5Cao.85)o.75Si9.3Al2.70i.₂N i4.8 [CoiTip-1 ]; (Eu₀.i5Cao.85)i.oSi8.8Al3.20i.₂Ni4.8 [Comp- 2]; (Euo.o75Cao.925)i.oSiB.eAl3.20i.₂Ni4.e [Comp-3]; (Euo.isCao.sskoSisjAle.sC^.sNisj [Comp-4]; (Euo.ioCao.9o)3.oSi2.6Al9.40₃.4Ni2.6 [Comp-5];

(Eu₀.i oCao.9o)3.oSii .8Ali o.20₄.2N i i .8 [Comp-6];

[Comp- ]; (EUo.075Cao.925)l.oSi8.₆Al3.40l.₄Nl4.6 [Comp-8]; (EU₀.075Cao.925)l.oSi9.oAI₃.oOl.oNi 5.0

[Comp-9]; (Euo.i5Ca₀.85)i .oSi9.oAI₃.oOi .oNi 5.o [Comp-10];

(EUo.075Cao.925)l.oSi8.₃Al3.70l .₇Ni4.3 [Comp-1 1 ]; (EUo.075Cao.925)l .oSi_B.4Al3.eOi.eNi4.4

[Comp-12]; (Eu₀.o75Cao.925)i .oSi8.7Al3.30i.₃Ni4.7 [Comp-13];

(EUo.05Cao.95)l.25Si8.oAI₄.oOl .5N l4.5 [Comp-14]; (EU₀.05Cao.95)l.25Si7.75AI₄.250i.75Ni4.25

[Comp-15]; (Eu₀.o5Cao.95)i .25Si7.5Al4.50₂.oNi4.o [Comp-16].

[0046] In some embodiments, the phosphor variants can be selected from optionally: (Eu₀.o75Cao.925)i.oSi8.6Al3.40i.₄N i4.6 [Comp-8];

(EUo.075Cao.925)l.oSi8.3Al3.70l .₇Nl4.3 [Comp-1 1 ]; (EUo.075Cao.925)SiB.4AI₃.eOi.eNi4.4

[Comp-12];

.sN .s [Comp-14];

(EUo.05Cao.95)l.25Si7.75AI₄.250i.75Ni4.25 [Comp-15]; (EUo.05Cao.95)l.25Si7.5AI₄.502.oNi4.0

[Comp-16].

[0047] In some embodiments, a phosphor variant can comprise

(Euo.o75Cao.925)i.oSi8.6AI₃.40i .₄Ni4.6 [Comp-8] and/or (Euo.075Cao.925) 1.0S18.3AI3.7O1.7N14.3 [Comp-1 1 ]. [0048] In some embodiments, the phosphor can comprise a crystalline phosphor. In other embodiments, the phosphor can comprise a polycrystalline phosphor. In some embodiments, the nitride phosphor ceramic element can comprise multiple phosphor compositions which satisfy Formula 1 . In other embodiments, the nitride phosphor ceramic element comprises a single phosphor composition which meets Formula 1 . In some embodiments, the resulting phosphor composition comprises at least 90 vol%, 95 vol%, and/or 97 vol% a-phase SiAION phosphor material. In some embodiments, the resulting composition comprises less than 10 vol%, 5 vol%, and/or 3 vol% β-phase SiAION phosphor material. These phosphors may be prepared by a method described herein, or may be prepared by another method.

[0049] With respect to Formula 1 , in some embodiments, x is about 0.02- 0.3, about 0.05-0.15, about 0.05-0.1 , about 0.1 -0.14, about 0.05, about 0.075, about 0.1 , about 0.15, or any value in a range bounded by any of these values.

[0050] With respect to Formula 1 , in some embodiments, m is about 0.5-6, about 1 -3, about 1 -1 .5, about 1 .5-2, about 2-2.5, about 2.5-3, about 3-4, about 4-5, about 5-6, about 1 .5, about 2, about 4, about 6, or any value in a range bounded by any of these values.

[0051] With respect to Formula 1 , in some embodiments, n is about 0.5-5, about 1 -3, about 1 -1 .5, about 1 .5-2, about 2-2.5, about 2.5-3, about 3-4, about 4-5, about 1 , about 1 .1 , about 1 .2, about 1 .4, about 1 .6, about 1 .65, about 1 .7, about 2, about 2.4, about 2.3, about 2.8, about 3.2, about 3.4, about 3.6, about 4.2, about 4.8, or any value in a range bounded by any of these values.

[0052] Some ceramic elements comprising compositions of Formula 1 emit orange light when excited by absorption of visible light, such as absorption of violet, blue, green, or yellow light. Orange light includes any light that an ordinary person would perceive as orange, such as light having CIE coordinates (see FIG. 7) bounded by an area defined by the lines [(x,y)-(x,y)] [(3.3,3.7)-(5.1 ,4.8)] and [(3.3,3.7)-(2.5,6.0)]; light having a T_c value of about, 1000-3000 K, about 1000-2000 K, about 2000-3000 K, about 2500 K; light appearing to have the same color as visible light having a wavelength of about 580-630 nm or 590-620 nm; light primarily in the range of about 580-630 nm or 590-620 nm; or light having a spectrum with a major peak in the range of about 580-630 nm or 590-620 nm.

[0053] A ceramic element may be in the form of a sintered ceramic plate. A sintered ceramic plate may be shaped such that the thickness of the plate, or the average thickness of the plate, is significantly less than the length, width, or the square root of the area, of a surface of the plate that is normal to the direction of the thickness. Typically, a plate will have a surface area around 0.5 mm²-100 cm², while having a thickness of less than about 500 μιη, less than 400 μιη, less than 300 μιη, or about 50-100 μιη, about 100-125 μιη, about 125-150 μιη, about 150-175 μιη, about 175-200 μιη, about 200-250 μιη, or about 250-300 μιη.

[0054] A nitride phosphor ceramic element can further comprise a sintering aid such as TEOS, Si0₂, Zr, or Mg or Ca silicates and fluorides such as but not limited to tetraethoxysilane (TEOS), colloidal silica and mixtures thereof; oxides and fluorides such as but not limited to lithium oxide, titanium oxide, zirconium oxide, barium oxide, calcium oxide, magnesium oxide, strontium oxide, boron oxide, calcium fluoride, and mixtures thereof. In some embodiments, the sintering aid can comprise at least magnesium oxide and/or calcium oxide. In some embodiments, the mass ratio of the sintering aid can vary from about 0.01 %wt to about 5.0%wt.

[0055] In some embodiments, the nitride phosphor ceramic element can also comprise dispersants such as ammonium salts, e.g. , NH₄CI; Flowlen; fish oil; long chain polymers; stehc acid; oxidized Menhaden Fish Oil (MFO); dicarboxylic acids such as but not limited to succinic acid, ethanedioic acid, propanedioic acid, pentanedioic acid, hexanedioic acid, heptanedioic acid, octanedioic acid, nonanedioic acid, decanedioic acid, o-phthalic acid, and p-phthalic acid; sorbitan monooleate; and mixtures thereof. Some embodiments preferably use oxidized MFO as a dispersant.

[0056] In some embodiments, nitride phosphor ceramic can additionally comprise plasticizers, which include Plasticizers type 1 which can generally decrease the glass transition temperature (Tg), e.g. makes it more flexible, phthalates (n-butyl, dibutyl, dioctyl, butyl benzyl, missed esters, and dimethyl); and Plasticizers type 2, which can enable more flexible, more deformable layers, and perhaps reduce the amount of voids resulting from lamination, e.g., glycols (polyethylene; polyalkylene; polypropylene; triethylene; dipropylglycol benzoate).

[0057] Type 1 plasticizers can include, but are not limited to, butyl benzyl phthalate, dicarboxylic/tricarboxylic ester-based plasticizers such as but not limited to phthalate-based plasticizers such as but not limited to bis(2-ethylhexyl) phthalate, diisononyl phthalate, bis(n-butyl)phthalate, butyl benzyl phthalate, diisodecyl phthalate, di-n-octyl phthalate, diisooctyl phthalate, diethyl phthalate, diisobutyl phthalate, di-n-hexyl phthalate and mixtures thereof; adipate-based plasticizers such as but not limited to bis(2-ethylhexyl)adipate, dimethyl adipate, monomethyl adipate, dioctyl adipate and mixtures thereof; sebacate-based plasticizers such as but not limited to dibutyl sebacate, and maleate.

[0058] Type 2 plasticizers can include, but are not limited to, dibutyl maleate, diisobutyl maleate and mixtures thereof, polyalkylene glycols such as but not limited to polyethylene glycol, polypropylene glycol and mixtures thereof. Other plasticizers which may be used include, but are not limited to, benzoates, epoxidized vegetable oils, sulfonamides such as but not limited to N-ethyl toluene sulfonamide, N-(2-hydroxypropyl)benzene sulfonamide, N-(n-butyl)benzene sulfonamide, organophosphates such as but not limited to tricresyl phosphate, tributyl phosphate, glycols/polyethers such as but not limited to triethylene glycol dihexanoate, tetraethylene glycol diheptanoate and mixtures thereof; alkyl citrates such as but not limited to triethyl citrate, acetyl triethyl citrate, tributyl citrate, acetyl tributyl citrate, trioctyl citrate, acetyl trioctyl citrate, trihexyl citrate, acetyl trihexyl citrate, butyryl trihexyl citrate, trimethyl citrate, alkyl sulphonic acid phenyl ester and mixtures thereof.

[0059] In some embodiments, nitride phosphor ceramic element can also comprise binders. In some embodiments, organic binders can be used. In some embodiments, the organic binders used can comprise vinyl polymers such as but not limited to polyvinyl butyral (PVB), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), polyvinyl acetate (PVAc), polyacrylonitrile, mixtures thereof and copolymers thereof; polyethyleneimine; poly methyl methacrylate (PMMA); vinyl chloride-acetate; and mixtures thereof. Some embodiments preferably use PVB as an organic binder. [0060] In some embodiments, in the methods described herein, the dispersant solution can comprise a non-polar solvent. In some embodiments, the non-polar solvent can be an organic solvent. In some embodiments, the non-polar solvent can include, but is not limited to, a lower alkanol such as but not limited to ethanol, methanol, isopropyl alcohol, xylenes, cyclohexanone, acetone, toluene and methyl ethyl ketone, and mixtures thereof. In some embodiments, the non-polar solvent can be toluene.

[0061] Consistent with some embodiments, as seen in FIG. 1 , a lighting device, 100, comprises at least a phosphor ceramic element, 120, and a light emitting diode (LED) device, 110. In some embodiments, the electric current is provided by the conducting wires, 140, through the conductive base, 150, to the LED in order to emit light. The LED, 110, can emit primary light which excites the phosphor in the ceramic element, 120, to generate complementary light which combines with the primary light to create a soft-white light before exiting the encapsulating resin, 130. In some embodiments, the phosphor ceramic element, 120, is applied as a plate covering the LED as opposed to the phosphor being suspended as particles above the LED within the encapsulating resin, 310. In some embodiments the LED outputs light with a peak intensity from about 430 nm to about 470 nm. In some embodiments, the LED, 110, is a blue LED with a peak wavelength of 450 nm. In some embodiments, the phosphor ceramic element, 120, defines an orange phosphorescence when excited by a blue LED. In some embodiments, the lighting device, 100, can provide soft-white light as the result of the blue LED and the orange phosphorescence.

EXAMPLES

[0062] It has been discovered that embodiments of phosphor and LED elements described herein have promise to provide orange emissions for producing a warm-white light. These benefits are further shown by the following examples, which are intended to be illustrative of the embodiments of the disclosure, but are not intended to limit the scope or underlying principles in any way. Example 1 :

[0063] In Example 1 , Phosphor Element 1 (PE-1 ) was prepared by following the method outlined above for synthesizing the ceramic composition. The overall process used in Example 1 is depicted in FIG. 2.

[0064] First, 21 g of poly vinyl butyal-co-vinyl alcohol-co-vinyl acetate (Aldrich, St. Louis, MO, USA), 10.5 g of benzyl n-butyphthate (Alfa Aesar, Ward Hill, MA, USA), 10.5 g of poly ethylene glycol (Mn=400, Aldrich) were mixed in 90.0 g toluene (Fisher Scientific, Pittsburg, PA, USA) to form a binder solution. Then, a 50 ml high purity Zr0₂ ball mill jar was filled with 55g of Zr0₂ balls of about 3 mm in diameter. Next, 0.95 g Eu₂0₃ powder, 3.06 g CaC0₃ powder, 20.85 g of Si₃N₄ powder, 4.72 g of AIN powder, 0.73 g of Al₂0₃ powder, 0.30 g MgO powder, 0.60 g dispersant Flowlen G700 (Kyeisha Chemical Co., Ltd., Osaka, JP) were ball milled with 20.0 g of binder solution and additional 15.0 g of toluene (reagent grade, Fisher Scientific) for about 24 hours. The resulting composition, Comp-1 , conformed to the requirements of Formula 1 with an index of x of about 0.15 and index of m of about 1 .5 and an index of n of about 1 .2. Then, MgO (1 weight parts per hundred) was added as sintering aid to facilitate liquid phase sintering, and all other solid components made up of the a-SiAION phosphors.

[0065] When ball milling was complete, the resulting slurry was passed through a syringe-aided metal screen filter with pore size of 0.05 mm. The slurry was then cast on a releasing substrate, e.g., silicone coated Mylar® carrier substrate (Tape Casting Warehouse, Morrisville, PA, USA) with an adjustable film applicator (Paul N. Gardner Company, Inc., Pompano Beach, FL, USA) at a cast rate of 30 cm/min. The blade gap on the film applicator was set at 0.254 mm (10 mil). The cast tape was dried overnight at about 60 °C inside an air-circulating oven to produce a light yellow-colored green form of about 35 μιη thickness.

[0066] The dried-cast tape of the phosphor material (e.g. 50 μιη thick) comprising SiAION precursors were cut into square shape of 100 mm x 100 mm with a razor blade. The respective green sheets were then laminated on an anodized aluminum substrate, and then the laminates on the aluminum substrate was vacuum-bagged for a cold isostatic press (CIP) process. The laminated samples were heated to 85 °C and pressed at an isostatic pressure of 42 MPa for 10 minutes.

[0067] For debinding, the laminated green sheets were sandwiched between Al₂0₃ cover plates (1 mm thick, grade 42510-X, ESL Electroscience Inc. , King of Prussia, PA, USA); then heated in an alumina tube furnace (MTI Corporation, Richmond, CA, USA) in air at a ramp rate of 0.5 °C/min to 700 °C and held for 3 hours to remove the organic components from the green from to generate a brown form. A plurality of the laminate compacts was stacked between porous Al₂0₃ cover plates, alternately.

[0068] After debinding, the brown forms were bisque-fired in the same alumina tube furnace at 1200 °C in a flowing N₂ gas (flow rate of less than 100 ml/min, Airgas, San Marcos, CA, USA) for 2 hours in order to get sufficient strength for further handling during the fabrication process.

[0069] After bisque-firing, the brown forms were then sintered in a furnace with a graphite heater and carbon felt lining. To prepare for sintering, the bisque- fired brown forms were first sandwiched between boron nitride (BN) cover plates instead of Al₂0₃ cover plates, and these were embedded in sacrificial packing powder comprised of 60 wt% BN / 40 wt% Si₃N₄ powder mixture in a BN crucible in order to reduce partial reduction of the samples to constituent metals due to strong reducing atmosphere caused by the graphite materials of the furnace. A plurality of the brown compacts was stacked between the BN cover plates, alternately, inside the BN crucible. After being embedded in packing powder, the brown forms were then further sintered in flowing N₂ gas (Airgas) at 1625 °C for a duration of 24 hours at a heating rate of about 3 °C/min and a cooling rate of about 10 °C/min to room temperature to produce a translucent SiAION ceramic sheet with a thickness of about 0.1 mm to about 0.5 mm.

[0070] After sintering, the ceramic sheet then underwent HIP at 1875 °C at a pressure of 35 MPa for duration of about 1 hr. As a result, a composition consisting of a laminate composite of an emissive Solid-State-Reaction (SSR) sheet (total pre-sintering thickness of about 290 μιη and total post-sintering thickness of about 227 μιη) was formed (PE-1 ). Example 2:

[0071] In Example 2, composition Comp-2 was made in a similar manner as Comp-1 in Example 1 , with the exception that the stoichiometric amounts of the precursors were varied to achieve the values of x, m, and n associated with Comp-2 as described in Table 1 .

Table 1 : Various a- iAION Compositions.

[0072] In addition, phosphor elements PE-2 through PE-3 were created using composition Comp-2 and implementing the methodology used in Example 1 with the exceptions that the process and sintering parameters were varied as described in Table 2 below and HIP was done at 1675 °C instead of 1875 °C. Additionally, due to the fact that Internal Quantum Energy (IQE) measurements are destructive in nature, the phosphor elements which were chosen to be measured are also identified.

Table 2: Method Variances for Example 2.

Example 3:

[0073] In Example 3, composition Comp-3 was made in a similar manner as Comp-1 in Example 1 , with the exception that the stoichiometric amounts of the precursors were varied to result in the desired values of x, m, and n associated with Comp-3 as described in Table 1 .

[0074] In addition, phosphor elements PE-4 through PE-30 were created using composition Comp-3 and applying the same methodology used in Example 1 with the exceptions that the process and sintering parameters were varied as described in Table 3 below and HIP was done at 1675 °C instead of 1875 °C. Where delineated as using "fast cooling" after the sintering process, the elements were cooled without using heated nitrogen gas to maintain cooling rates of about 10 °C/min, allowing unfettered cooling. Additionally, due to the fact that IQE measurements are destructive in nature, the elements which were chosen to be measured post-sintering or post-HIP are also identified.

Table 3: Method Variances for Example 3.

Sintering Param. Fast Post-Sint. IQE Meas

ID# Comp. x [ ] n [ ] n [ ] Cooling Meas. HIP'd

ID Temp Time Thick Tt% Post- Post- [°C] [hrs] [Mm] [%] Sint HIP

PE-23 COMP-3 0.075 2.0 1 .2 1675 8 hrs N 120 16.4 X

PE-24 COMP-3 0.075 2.0 1 .2 1675 8 hrs N 139 13.6

PE-25 COMP-3 0.075 2.0 1 .2 1675 8 hrs N 140 22.5

PE-26 COMP-3 0.075 2.0 1 .2 1675 8 hrs Y 130 30.6

PE-27 COMP-3 0.075 2.0 1 .2 1675 8 hrs Y 140 5.4

PE-28 COMP-3 0.075 2.0 1 .2 1675 8 hrs Y 1 17 1 1.7 X

PE-29 COMP-3 0.075 2.0 1 .2 1700 8 hrs Y 126 33.2

PE-30 COMP-3 0.075 2.0 1 .2 1700 8 hrs Y 132 41.5

Example 4:

[0075] In Example 4, composition Comp-4 was made in a similar manner as Comp-1 in Example 1 , with the exception that the stoichiometric amounts of the precursors were varied to result in the desired values of x, m, and n associated with Comp-4 as described in Table 1 .

[0076] In addition, phosphor elements PE-31 through PE-50 were created using composition Comp-4 and applying the same methodology used in Example 1 with the exceptions that the process and sintering parameters were varied as described in Table 4 below and HIP was done at 1675 °C instead of 1875 °C. Where delineated as using "fast cooling" after the sintering process, the elements were cooled without using heated nitrogen gas to maintain cooling rates of about 10 °C/min, allowing unfettered cooling. Additionally, due to the fact that IQE measurements are destructive in nature, the elements which were chosen to be measured post-sintering or post-HIP are also identified.

Table 4: Method Variances for Example 4.

PE-36 COMP-4 0.15 4.0 2.3 1650 8 hrs N 130 31 .7

PE-37 COMP-4 0.15 4.0 2.3 1650 8 hrs N 93 40.6 X

PE-38 COMP-4 0.15 4.0 2.3 1675 8 hrs N 127 34.2 X

PE-39 COMP-4 0.15 4.0 2.3 1675 8 hrs N 130 37.7

PE-40 COMP-4 0.15 4.0 2.3 1675 8 hrs N 76 27.5

PE-41 COMP-4 0.15 4.0 2.3 1675 8 hrs N 122 37.9

PE-42 COMP-4 0.15 4.0 2.3 1675 8 hrs N 120 25.4 X

PE-43 COMP-4 0.15 4.0 2.3 1675 8 hrs Y 129 32.1

PE-44 COMP-4 0.15 4.0 2.3 1675 8 hrs Y 92 37.6

PE-45 COMP-4 0.15 4.0 2.3 1675 8 hrs Y 138 32.9 X

PE-46 COMP-4 0.15 4.0 2.3 1675 8 hrs Y 84 43.7 X

PE-47 COMP-4 0.15 4.0 2.3 1675 8 hrs Y 127 30.2

PE-48 COMP-4 0.15 4.0 2.3 1675 8 hrs Y 85 42.1 X X

PE-49 COMP-4 0.15 4.0 2.3 1700 8 hrs Y 126 18.2

PE-50 COMP-4 0.15 4.0 2.3 1700 8 hrs Y 106 27.3

Example 5:

[0077] In Example 5, composition Comp-5 was made in a similar manner as Comp-1 in Example 1 , with the exception that the stoichiometric amounts of the precursors were varied to result in the desired values of x, m, and n associated with Comp-5 as described in Table 1 .

[0078] In addition, phosphor elements PE-51 through PE-55 were created using composition Comp-5 and applying the same methodology used in Example 1 with the exceptions that the process and sintering parameters were varied as described in Table 5 below and HIP was done at 1675 °C instead of 1875 °C. Where delineated as using "fast cooling" after the sintering process, the elements' were cooled without using heated nitrogen gas to maintain cooling rates of about 10 °C/min, allowing unfettered cooling. In this example, these phosphor elements became stuck to the Al₂0₃ plate, possibly because of the high Al content, so thickness and transmittance could not be measured.

Table 5: Method Variances for Example 5.

PE-53 COMP-5 0.10 6.0 3.4 1675 8 hrs Y 156 29.7

PE-54 COMP-5 0.10 6.0 3.4 1675 8 hrs Y N/A N/A

PE-55 COMP-5 0.10 6.0 3.4 1675 8 hrs Y N/A N/A

Example 6:

[0079] In Example 6, composition Comp-6 was made in a similar manner as Comp-1 in Example 1 , with the exception that the stoichiometric amounts of the precursors were varied to result in the desired values of x, m, and n associated with Comp-6 as described in Table 1 .

[0080] In addition, phosphor elements PE-56 through PE-60 were created using composition Comp-6 and applying the same methodology used in Example 1 with the exceptions that the process and sintering parameters were varied as described in Table 6 below and HIP was done at 1675 °C instead of 1875 °C. Where delineated as using "fast cooling" after the sintering process, the elements were cooled without using heated nitrogen gas to maintain cooling rates of about 10 °C/min, allowing unfettered cooling. In this example, like in Example 5, the phosphor elements became stuck to the Al₂0₃ plate, possibly because of the high Al content, and thickness and transmittance could not be measured.

Table 6: Method Variances for Example 6.

Example 7:

[0081] In Example 7, composition Comp-7 was made in a similar manner as Comp-1 in Example 1 , with the exception that the stoichiometric amounts of the precursors were varied to result in the desired values of x, m, and n associated with Comp-7 as described in Table 1 .

[0082] In addition, phosphor elements PE-61 through PE-75 were created using composition Comp-7 and applying the same methodology used in Example 1 with the exceptions that the process and sintering parameters were varied as described in Table 7 below and HIP was done at 1675 °C instead of 1875 °C. Where delineated as using "fast cooling" after the sintering process, the elements' were cooled without using heated nitrogen gas to maintain cooling rates of about 10 °C/min, allowing unfettered cooling. Additionally, due to the fact that IQE measurements are destructive in nature, the elements which were chosen to be measured post-sintering or post-HIP are also identified.

Table 7: Method Variances for Example 7.

Example 8:

[0083] In Example 8, composition Comp-8 was made in a similar manner as Comp-1 in Example 1 , with the exception that the stoichiometric amounts of the precursors were varied to result in the desired values of x, m, and n associated with Comp-8 as described in Table 1 .

[0084] In addition, phosphor elements PE-76 through PE-109 were created using composition Comp-8 and applying the same methodology used in Example 1 with the exceptions that the process and sintering parameters were varied as described in

[0085] Table 8 below and HIP was done at 1675 °C instead of 1875 °C. Where delineated as using "fast cooling" after the sintering process, the elements were cooled without using heated nitrogen gas to maintain cooling rates of about 10 °C/min, allowing unfettered cooling. Additionally, due to the fact that IQE measurements are destructive in nature, the elements which were chosen to be measured post-sintering or post-HIP are also identified. Table 8: Method Variances for Example 8.

Example 9:

[0086] In Example 9, composition Comp-9 was made in a similar manner as Comp-1 in Example 1 , with the exception that the stoichiometric amounts of the precursors were varied to result in the desired values of x, m, and n associated with Comp-9 as described in Table 1 .

[0087] In addition, phosphor elements PE-110 through PE-119 were created using composition Comp-9 and applying the same methodology used in Example 1 with the exceptions that the process and sintering parameters were varied as described in Table 9 below and HIP was done at 1675 °C instead of 1875 °C. Where delineated as using "fast cooling" after the sintering process, the elements were cooled using nitrogen gas to accelerate the cooling process. Additionally, due to the fact that IQE measurements are destructive in nature, the elements which were chosen to be measured post-sintering or post-HIP are also identified.

Table 9: Method Variances for Example 9.

Example 10:

[0088] In Example 10, composition Comp-10 was made in a similar manner as Comp-1 in Example 1 , with the exception that the stoichiometric amounts of the precursors were varied to result in the desired values of x, m, and n associated with Comp-10 as described in Table 1 .

[0089] In addition, phosphor elements PE-120 through PE-127 were created using composition Comp-10 and applying the same methodology used in Example 1 with the exceptions that the process and sintering parameters were varied as described in Table 10 below and HIP was done at 1675 °C instead of 1875 °C. Where delineated as using "fast cooling" after the sintering process, the elements were cooled using nitrogen gas to accelerate the cooling process. Additionally, due to the fact that IQE measurements are destructive in nature, the elements which were chosen to be measured post-sintering or post-HIP are also identified.

Table 10: Method Variances for Example 10.

Example 1 1 :

[0090] In Example 1 1 , composition Comp-11 was made in a similar manner as Comp-1 in Example 1 , with the exception that the stoichiometric amounts of the precursors were varied to result in the desired values of x, m, and n associated with Comp-11 as described in Table 1 .

[0091] In addition, phosphor elements PE-128 through PE-138 were created using composition Comp-11 and applying the same methodology used in Example 1 with the exceptions that the process and sintering parameters were varied as described in Table 11 below and HIP was done at 1675 °C instead of 1875 °C. Additionally, due to the fact that IQE measurements are destructive in nature, the elements which were chosen to be measured post-sintering or post-HIP are also identified.

Table 11 : Method Variances for Example 11.

Comparative Example 1 :

[0092] In Comparative Example 1 , phosphor elements CPE-1 through CPE-32 were created using compositions Comp-1 through Comp-4 and applying the same methodology used in Example 1 with the exception of the deviations identified herein. The stoichiometric amounts of the precursors were varied to result in the desired values of x, m, and n that correspond to the specific composition identified for each CPE as described in Table 12. For CPE-10, MgO was not added as a liquid phase sintering aid in order to determine its effect. In addition to the stoichiometric variations, the methodology in Example 1 was also varied as described in Table 12. In this example, HIP temperature did not deviate from Example 1 and was done at 1875 °C. Table 12: Method Variances for Comparative Example-1.

Sintering Param. Fast Post-Sint. IQE Meas

ID# Comp. x[ ] n [ ] n [ ] Cooling Meas. HIP'd

ID Temp Time Thick Tt% Post- Post- PC] [hrs] [Mm] [%] Sint HIP

CPE- COMP-4 0.15 4.0 2.3 1700 8 hrs N See 44.9 X

30 Note 2

CPE- COMP-4 0.15 4.0 2.3 1725 8 hrs N See 44.2 X

31 Note 2

CPE- COMP-4 0.15 4.0 2.3 1750 8 hrs N See 39.8 X

32 Note 2

Notes:

[1] For these elements, thickness and transmittance was not measured after sintering; instead transmittance and IQE was measured after HIP.

[2] For these elements, thickness was note measured after sintering.

[3] For element CPE-10, MgO was not added to the composition as a sintering aid.

Example 12:

[0093] The laminate composites identified in Examples 1 through 1 1 and Comparative Example 1 were each examined to determine their optical characteristics as identified in their respective sections.

[0094] The transmittances of the obtained sintered phosphor plates were measured by high sensitivity multi channel photo detector (MCPD 7000, Otsuka Electronics Co., Ltd., Osaka, JP). First, a glass plate was irradiated with continuous spectrum light from a halogen lamp source (150 W, MC2563, Otsuka Electronics Co., Ltd.) to obtain reference transmission data. Next, each phosphor plate was placed on the reference glass and irradiated. The transmission spectrum was acquired by the photo detector (MCPD) for each sample. In this measurement, each phosphor plate on the glass plate was coated with paraffin oil having the same refractive index as the glass plate. Transmittance at 800 nm wavelength of light was used as a quantitative measure of transparency of the phosphor ceramic plates.

[0095] Next the ceramic compact samples, were then each mounted onto a blue LED chip (Cree [Durham, N.C., USA] blue-LED chip, dominant wavelength 455nm, C455EZ1000-S2001 ) and the LED was operated at DC 100 mA at 2.9 V to excite the samples. Total light transmittance data for the samples was measured for each sample by using the measurement system as described in U.S. Patent Publication No. 2009-0212697, published August 27, 2099, Ser. No. 12/389,207, filed February 19, 2009 (MCPD 7000, Otsuka Electronics, Inc, Xe lamp, monochromator, and integrating sphere equipped). Photoluminescent spectrum of the samples excited by a blue light (the peak wavelength was 460 nm) from monochromator was also acquired by using same photo detector.

[0096] For the samples created in Comparative Example 1 were measured as denoted in Table 12 with some samples being measured before the post-sintering and some samples measured after the HIP treatment with the purpose of determining the impact of the HIP treatment. The results of the measurements are presented in Table 13. Total transmittance (Tt%) and the Internal Quantum Efficiency (IQE) before the HIP treatment for CPE-1 1 through CPE-32 are shown in FIG. 3, grouped according to variations in Composition. Tt% and IQE for selected samples after the HIP treatment, CPE-1 through CPE-1 1 are also shown in FIG. 4. Although Example 4, measured after sintering, had a high Al content (m = 4) and showed a higher Tt%, the HI P process resulted in a Tt% reduction. After complete characterization of the samples that underwent HIP at 1875 °C as compared to those that did not, it was noted that most samples had a high β-SiAION concentration and the 1875 °C temperature did not maintain the a-SiAION structure.

Table 13: Measurements for Comparative Example-1.

Sintering Param. Post -Sintering Post-HIP

ID# Comp. Temp Time Fast Thickness Thickness

ID PC] [hrs] Cooling [mm] Tt% IQE [mm] Tt% IQE λρ

CPE- 30 COMP-4 1700 8 hrs N N/A 44.9 58 590

CPE-

31 COMP-4 1725 8 hrs N N/A 44.2 35 598

CPE- 32 COMP-4 1750 8 hrs N N/A 39.8 52.5 593

Notes:

[1] For e ilement C ³E-10, Mg O was not added to 1 he composition as a sinte ring aid.

[0097] For Examples 2 through 1 1 , the elements identified in the corresponding tables in each example as being measured before or after the HIP treatment were examined in order to determine the relative impact of the HIP treatment at 1675 °C. The results of the measurements are presented in Table 14. Tt% and IQE before the HIP treatment for the corresponding selected samples is shown in FIG. 5. Tt% and IQE after the HIP treatment for the corresponding selected samples are shown in FIG. 6. The variances in composition had significant effects on IQE with the best sample that underwent HIP treatment having a Transmittance of about 55% and an IQE of about 65%. Specifically, as indicated in FIG. 6, compositions Comp-8 and Comp-1 1 , which had low Al content (or m = 2) had better performance. For composition Comp-8 the best performing element was PE- 104 (with a thickness of 79 mm, a transmittance of 55.4%, and an IQE of 67%). For composition Comp-1 1 the best performing element was PE-136 (with a thickness of 93 mm, a transmittance of 52.9%, and an IQE of 63.7%).

Table 14: Measurements for Examples 2 through 11.

Sintering Param. Post-Sintering Post-HIP

ID# Comp. Temp Time Fast Thickness Thickness λρ

ID PC] [hrs] Cooling [mm] Tt% IQE [mm] Tt% IQE [2]

PE-23 COMP-3 1675 8 hrs N 120 16.4 128 6.1 [1 ] PE-28 COMP-3 1675 8 hrs Y 1 17 1 1.7 64.5 590 PE-31 COMP-4 1625 24 hrs N 54 49.8 43.9 588

PE-32 COMP-4 1650 16 hrs N 133 39.4 37.2 583 PE-33 COMP-4 1650 16 hrs N 135 31.7 38 584 PE-34 COMP-4 1650 16 hrs N 50 50.7 73 43.1 42.6 PE-37 COMP-4 1650 8 hrs N 93 40.6 89 36.8 [1 ] PE-38 COMP-4 1675 8 hrs N 127 34.2 35.9 582 PE-42 COMP-4 1675 8 hrs N 120 25.4 33.5 585

PE-45 COMP-4 1675 8 hrs Y 138 32.9 135 18 [1 ] PE-46 COMP-4 1675 8 hrs Y 84 43.7 87 19.9 [1 ] PE-48 COMP-4 1675 8 hrs Y 85 42.1 88 40 40 PE-61 COMP-7 1625 24 hrs N 51 47.7 55 42.9 43.6

PE-62 COMP-7 1650 16 hrs N 146 44 140 32 [1 ] PE-63 COMP-7 1650 16 hrs N 144 33.9 146 32.3 [1 ] PE-66 COMP-7 1650 16 hrs N 47 49.4 26 593 PE-67 COMP-7 1675 8 hrs N 136 30.7 24 590

PE-68 COMP-7 1675 8 hrs N 136 34.4 149 48.8 64.4 PE-69 COMP-7 1675 8 hrs N 130 35 23.1 595 PE-73 COMP-7 1675 8 hrs Y 137 34.3 137 34.7 [1 ] PE-76 COMP-8 1625 24 hrs N 166 20.9 166 14 [1 ] PE-77 COMP-8 1625 24 hrs N 60 32.8 67.3 590

PE-83 COMP-8 1650 16 hrs N 86 35.1 85 43.1 [1 ] PE-85 COMP-8 1650 8 hrs N 135 32.8 153 53.3 64.6 PE-86 COMP-8 1650 8 hrs N 165 35.3 162 48.5 [1 ] PE-87 COMP-8 1650 8 hrs N 74 38.9 68 587 PE-88 COMP-8 1650 8 hrs N 76 37.5 67 590

PE-89 COMP-8 1650 8 hrs N 107 38.2 70 49.3 63.5 PE-90 COMP-8 1675 8 hrs N 135 46 136 48.2 [1 ] PE-92 COMP-8 1675 8 hrs N 155 39.4 145 50.8 [1 ] PE-97 COMP-8 1675 8 hrs Y 139 38.2 145 36.1 [1 ] PE-98 COMP-8 1675 8 hrs Y 167 10.9 58.2 594 PE-99 COMP-8 1675 8 hrs Y 145 44 146 48.3 [1 ] PE-100 COMP-8 1675 8 hrs Y 151 29.1 142 46.8 [1 ]

PE-103 COMP-8 1675 8 hrs Y 150 42.6 63.6 590 PE-104 COMP-8 1675 8 hrs Y 78 43.5 79 55.4 67 PE-105 COMP-8 1675 8 hrs Y 84 27.4 66.3 591 PE-106 COMP-8 1675 8 hrs Y 82 28.3 86 26.9 [1 ] PE-107 COMP-8 1675 8 hrs Y 159 25.9 161 33.7 [1 ] PE-1 12 COMP-9 1650 16 hrs N 152 30.9 151 43.5 67.2 PE-1 15 COMP-9 1675 8 hrs N 147 21.2 150 25.5 [1] Sintering Param. Post-Sintering Post-HIP

ID# Comp. Temp Time Fast Thickness Thickness λρ

ID PC] [hrs] Cooling [mm] Tt% IQE [mm] Tt% IQE [2]

PE-1 17 COMP-9 1675 8 hrs N 100 15.5 64.3 Γ3^J1J

PE-1 18 COMP-9 1675 8 hrs N 138 21.1 141 23.7 [1] PE-1 19 COMP-9 1675 8 hrs N 114 10 63.8 13^J1J

PE-123 COMP- 1650 16 hrs N 172 27.6 168 43.8 52.1 10

PE-125 COMP- 1675 8 hrs N 177 20 178 14.8 [1 ] 10

PE-126 COMP- 1675 8 hrs N 1 12 10.8 52.4 [3]

10

PE-127 COMP- 1675 8 hrs N 172 15.4 174 7.5 [1 ] 10

PE-128 COMP- 1650 24 hrs N 84 53.8 60.9 [3]

11

PE-131 COMP- 1650 16 hrs N 97 48.7 93 44.5 [1 ] 11

PE-132 COMP- 1650 16 hrs N 188 43.7 185 38.4 [1 ] 11

PE-133 COMP- 1675 8 hrs N 93 49.7 92 47.8 57.7 11

PE-134 COMP- 1675 8 hrs N 186 40.2 186 41 .6 [1 ] 11

PE-135 COMP- 1675 8 hrs N 193 38.9 192 49.7 63.5 11

PE-136 COMP- 1675 8 hrs N 92 48 93 52.9 63.7 11

PE-137 COMP- 1675 8 hrs N 89 49.7 61.2 [3] 11

PE-138 COMP- 1675 8 hrs N 86 50.5 58 [3] 11

Notes:

[1 ] For t hese sami Dies, the IC JE and pee ik waveler gth was not me ;asur 3d.

[2] Peak waveleng th was me as u red po st-s interim 3. For samples unde rgoinc 3 HIP the peak wave engt 1 was not inde pendently measured and instei ad is prese nted.

[3] For t iese sami Dies, peak wavelengt h was not measured; inst sad s pectr al quality of the comp )ositic >n was ver tied for th 3 samples that under went HIP.

Example 13:

[0098] In Example 13, five 1 .03 mm ^χ 1 .03 mm light-emitting diode (LED) device specimens (LED-1 through LED-5) containing the ceramic phosphor elements containing either composition Comp-8 or Comp-11 were created for testing. The ceramic phosphor elements for the specimens are identified in Table 15 below. The specimens were created by placing the phosphor element with paraffin oil (Aldrich) on top of a blue LED in order to characterize the properties of the resulting LED device. Table 15: LED Specimen Variances.

Notes:

[1 ] HIP was not conducted on this element

Example 14:

[0099] The specimens created in Example 13 (LEDs 1 through 5) were each examined to determine their optical characteristics. The methods for obtaining Transmittance and IQE were the same as in Example 12. Although presented first for clarity, IQE testing was done last due to its destructive nature. The corresponding optical characteristics are presented in Table 16.

Table 16: LED tical Characteristics.

[0100] For all LEDs, chromaticity was additionally measured with an MCPD 9800 multi channel photo detector system (Otsuka Electronics Co., Ltd.) connected with an integrate sphere (Gamma Scientific, San Diego, CA, USA) whose diameter was 300mm. The chromaticities of the samples are shown in FIG. 7 plotted on an International Commission on Illumination (CIE) 1931 X-Y plot. The sintered SiAION specimen (or LED-5) had lower CIE-x than the other four HIPed SiAIONs (or LED-1 through LED-4). Overall, composition Comp-8 (LED-1 and LED-2) appeared to be more orange than the other LEDs. It was observed that composition Comp-8 has potential to reach 2500K warm white. [0101] For all LEDs, their plug-in efficiency was also measured. The plug- in efficiency (or conversion efficiency [η₀]) is the ratio of emitted optical power to the provided electrical power and can be expressed by the following formula:

Equation 1 , where P₀ is the optical output power of the LED, i is the input current and V is the voltage differential across the LED.

[0102] Plug-in efficacies are shown in FIG. 8 and FIG. 9 for LEDs comprised of Comp-8 and Comp-1 1 respectively. Composition Comp-8 had a slightly higher efficacy than Comp-1 1 . Additionally, the sintered SiAION (LED-5) also exhibited lower efficacy than the ceramics that underwent HIP to reduce porosity. Overall, SiAION phosphor LEDs had about 75% as compared to YAG phosphor LEDs.

EMBODIMENTS

[0103] Embodiment P1 : A method for making a nitride phosphor ceramic element comprising: (a) mixing at least one precursor in a dispersant slurry; (b) tape casting the dispersant slurry to provide a green form; (c) debinding the green form at temperatures between about 400 °C to about 1000 °C for a period of time between about 30 minutes to about 36 hours to provide a brown form; (d) pressureless sintering the brown form at a temperature between about 1500 °C and about 1900 °C for a time period between about 3 hours to about 48 hours.

[0104] Embodiment P2: The method of Embodiment P1 , further comprising bisque-firing the brown form at a temperature between 800 °C to about 1400 °C for about 30 minutes to about 4 hours.

[0105] Embodiment P3: The method of Embodiment P1 or P2, further comprising adding a sintering aid to the dispersant slurry. [0106] Embodiment P4: The method of any one of Embodiments P1 -3, further comprising cold-isostatic pressing (CIP) the green form at between about 30 MPa to about 60 MPa for about 5 minutes to about 2 hours.

[0107] Embodiment P5: The method of any one of Embodiments P1 -4, further comprising hot-isostatic pressing (HIP) the sintered brown form at about 100 MPa to about 1000 MPa at between about 1600 °C to about 1750 °C for about 30 minutes to about 6 hours.

[0108] Embodiment P6: A ceramic element made by any of the methods described in Embodiments P1 -5 comprising at least a phosphor, whose emissive peak wavelength is between about 580 nm to about 620 nm, which is defined by the following chemical formula: (EuxCai-x^Si^-m-nAlm+nOnNie-n, Formula 1 , wherein 0.001 <x<0.25, 0.001 <m<7, and 0.001 <n<5.

[0109] Embodiment P7: The ceramic element of Embodiment P6, where the phosphor comprises at least one of the following

(EUo.15Cao.85)o.75Si9.3Al2. Ol .2N l₄.8; (EU₀.15Ca₀.85)l 0Si8.8AI3.2O1 2 l₄.8

(EUo.075Cao.925)l .oSi8.8Al3.20l .2Nl₄.8; (EU₀.15Cao.85)2.oSi5. Al6.302.3Nl 3.7

(EUo.1 oCao.9o)3.oSi2.6Alg.₄03.₄Ni2.6; (EU₀.1 oCao.9o)3.oSh δΑΙι 0.2θ₄.2Νι 1.8

(EUo.15Cao.85)2.oSi5.2Al6.802.8Nl 3.2; (EUo.0 5Cao.925)l oSi8.6Al3.₄Ol ₄Ni₄.6

(EUo.075Cao.925)l .oSi9.oAl3.oOl .oNl 5.o; (EUo.15Cao.85)l 0Si9.0AI3.0O1 0N15.0

(EUo.075Cao.925)l .oSi8.3Al3.70l .7Ni₄.3; (EUo.075Cao.925)l .oSl8.₄Al3.60l .βΝι_{4 4}

(EUo.075Cao.925)l .oSi8.7Al3.30l .3Ni₄.7; (EUo.05Cao.95)l .25Sl8.0AU.0O1.sNi₄.5 (EUo.05Cao.95)l .25Si7.75AI₄.250l .75Ni₄.25; (EUo.05Cao.95)l 25Si7.5AU.5O2.0 u 0.

[0110] Embodiment P8: The ceramic element of Embodiment P6 or P7, where the phosphor comprises at least (Euo.o75Cao.925)i .oSi₈.6AI₃.₄Oi .₄Ni₄.6 and/or

(EUo.075Cao.925)l .oSi8.3Al3.70l .7Ni₄.3.

[011 1 ] Embodiment P9: The ceramic element of any one of Embodiments P6-8, further comprising a sintering aid.

[0112] Embodiment P10: The ceramic element of Embodiment P9, wherein the sintering aid comprises MgO and/or CaO. [0113] Embodiment P1 1 : The ceramic of any one of Embodiments P6-10, wherein the element is more than 20 T_t% for all light in the wavelength ranging from to about 310 nm to about 500 nm.

[0114] Embodiment P12: A lighting device comprising the ceramic element in any one of Embodiments P6-1 1 and an LED, wherein the element is applied directly to the LED.

[0115] Embodiment P13: The lighting device of Embodiment P12, wherein the LED is a blue LED.

[0116] Embodiment P14: The lighting device of Embodiment P12 or P13, wherein the phosphor emits orange light, and wherein the lighting device provides a soft white light.

[0117] Embodiment P15: A nitride phosphor ceramic element comprising at least a phosphor, whose emissive peak wavelength is between about 580 nm to about 620 nm, the phosphor defined by the formula: (Eu_xCai-x)_m/2Sii2-m-nAL_m+nO_nNi6- n, Formula 2, wherein 0.001 <x<0.3, 0.001 <m<7, and 1 .5<n<5.

[0118] Embodiment P16: The nitride phosphor ceramic element of Embodiment P15, where the phosphor is comprised of at least one of the following:

(EUo.075Cao.925)l .oSi8.6Al3.₄Ol .₄Ni₄.6; (EUo.075Cao.925)l 0Si8.3AI3.7O1 7N14.3;

(EUo.0 5Cao.925)l .oSi8.₄Al3.60l .6Nl_{4 4}; (EUo.05Cao.95)l .25Si8.oAI₄.oOl .5Nl₄.5; (EUo.05Cao.95)l .25Si₇.75AI₄.250l .75Ni₄.25; (EUo.05Cao.95)l 25Si7.5AU.5O2 0 u.O-

[0119] Embodiment P17: The nitride phosphor ceramic element of Embodiments P15 or 16, where the phosphor is comprised of at least

(Euo.o 5Cao.925)1.0S18.6AI34O1 ₄N-|₄ 6 and/or (Euo.o7sCao.925)1 0Si8.3AI3.7O1.7N14.3.

[0120] Embodiment P18: The nitride phosphor ceramic element of any one of Embodiments P15-17, further comprising a sintering aid.

[0121] Embodiment P19: The nitride phosphor ceramic element of Embodiment P18, where the sintering aid is comprised of at least MgO and/or CaO. [0122] Embodiment P20: The nitride phosphor ceramic of any one of Embodiments P15-19, wherein the element is more than 20 T_t% at 800 nm light wavelength.

[0123] Embodiment P21 : A lighting device comprising the nitride phosphor ceramic element of any one of Embodiments P15-20 and an LED, wherein the nitride phosphor ceramic element is applied directly upon the LED.

[0124] Embodiment P22: The lighting device of Embodiment P21 , wherein the LED is a blue LED.

[0125] Embodiment P23: The lighting device of Embodiment P21 or P22, wherein the phosphor emits orange light, and wherein the lighting device provides a soft white light.

Embodiment 1. A method of preparing a nitride phosphor ceramic element comprising: heating a green form between about 400 °C to about 1000 °C for a period of about 30 minutes to about 36 hours to provide a brown form; and sintering the brown form at a temperature in a range of about 1500 °C to about 1900 °C for a time period between about 3 hours to about 48 hours.

Embodiment 2. The method of embodiment 1 , further comprising mixing at least one precursor in a dispersant slurry; and tape casting the dispersant slurry to provide the green form.

Embodiment 3. The method of embodiment 1 or 2, further comprising bisque-firing the brown form at a temperature between 800 °C to about 1400 °C for about 30 minutes to about 4 hours.

Embodiment 4. The method of embodiment 2 or 3, further comprising adding a sintering aid to the dispersant slurry.

Embodiment s. The method of embodiment 1 , 2, 3, or 4, further comprising cold-isostatic pressing (CIP) the green form at between about 30 MPa to about 60 MPa for about 5 minutes to about 2 hours. Embodiment 6. The method of embodiment 1 , 2, 3, 4, or 5, wherein the sintered brown form is subjected to hot isostatic pressing at 1600 °C to 1750 °C.

Embodiment 7. The method of embodiment 1 , 2, 3, 4, 5, or 6, wherein the sintered brown form is subjected to hot isostatic pressing at a pressure of about 15 MPa to about 70 MPa.

Embodiment 8. The method of embodiment 1 , 2, 3, 4, 5, 6, or 7, wherein the sintered brown form is subjected to hot isostatic pressing for about 10 min to about 2 hours.

Embodiment s. The method of embodiment 1 , 2, 3, 4, 5, 6, 7, or 8, wherein, after sintering, the brown form is cooled to room temperature at a rate of about 5 °C/min to about 20 °C/min.

Embodiment 10. The method of embodiment 1 , 2, 3, 4, 5, 6, 7, 8, or 9, wherein the sintering is carried out without applying external force or pressure to the brown form.

Embodiment 11. A ceramic element prepared by the method of embodiment 1 , 2, 3, 4, 5, 6, 7, 8, 9, or 10.

Embodiment 12. A ceramic element comprising a phosphor of Formula 1 :

(E U_xCai -x)_m/2S li 2-m-nAl_m+_nO_nN 16-n wherein x is between about 0.001 and about 0.25, m is between about 0.001 and about 7, and n is between about 0.001 and about 5.

Embodiment 13. The ceramic element of embodiment 12, which is in the form of a sintered ceramic plate.

Embodiment 14. The ceramic element of embodiment 12 or 13, wherein the sintered ceramic plate has a thickness of less than about 100 μιη.

Embodiment 15. The ceramic element of embodiment 12, 13, or 14, wherein x is a value in the range of 0.05 to 0.2. Embodiment 16. The ceramic element of embodiment 12, 13, 14, or 15, wherein m is a value in the range of 0.5 to 6.

Embodiment 17. The ceramic element of embodiment 12, 13, 14, 15, or

16, wherein n is a value in the range of 0.5 to 5.

Embodiment 18. The ceramic element of embodiment 12, 13, 14, 15, 16, or 17, having an emissive peak at a wavelength between about 580 nm and about 620 nm.

Embodiment 19. The ceramic element of embodiment 12, 13, 14, 15, 16,

17, or 18, which is emits orange light when excited by absorption visible light.

Embodiment 20. The ceramic element of embodiment 12, 13, 14, 15, 16, 17, 18, or 19, wherein the phosphor of Formula 1 is at least about 90 vol% a- phase.

Embodiment 21. A lighting device comprising the ceramic element of embodiment 12, 13, 14, 15, 16, 17, 18, 19, or 20 and an LED, wherein the element is applied directly upon the LED.

Embodiment 22. The lighting device of embodiment 21 , wherein the LED is a blue LED.

Embodiment 23. The lighting device of embodiment 21 or 22, wherein the phosphor emits orange light, and the lighting device provides a soft white light.

[0126] United State Provisional Patent Application No. 62/092,640, filed on Dec. 1 1 , 2014 is hereby incorporated by reference herein in its entirety.

[0127] Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims, if any, are approximations that may vary depending upon the desired properties sought to be obtained. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0128] The terms "a," "an," "the" and similar referents used in the context of describing embodiments of the present disclosure (especially in the context of the following claims, if any) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., "such as") provided herein is intended merely to better illuminate the disclosed embodiments and does not pose a limitation on the scope of this disclosure. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the teachings of this disclosure.

[0129] Groupings of alternative elements or embodiments disclosed herein are not to be construed as limitations. Each group member may be referred to and claimed individually or in any combination with other members of the group or other elements found herein. It is anticipated that one or more members of a group may be included in, or deleted from, a group for reasons of convenience and/or patentability

[0130] Certain embodiments are described herein, including the best mode known to the authors for carrying out the embodiments. Of course, variations on these described embodiments will become apparent to those of ordinary skill in the art upon reading the foregoing description. The authors expect skilled artisans to employ such variations as appropriate, and the authors intend for the teachings of the present disclosure to be practiced otherwise than specifically described herein. Accordingly, the claims include all modifications and equivalents of the subject matter recited in the claims as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is contemplated unless otherwise indicated herein or otherwise clearly contradicted by context.

[0131] In closing, it is to be understood that the embodiments disclosed herein are illustrative of the scope of the present disclosure. Other modifications that may be employed are within the scope of the disclosure. Thus, by way of example, but not of limitation, alternative embodiments may be utilized in accordance with the teachings herein. Accordingly, the disclosure is not limited to embodiments precisely as shown and described.

Claims

1 . A method of preparing a nitride phosphor ceramic element comprising: heating a green form between about 400 °C to about 1000 °C for a period of about 30 minutes to about 36 hours to provide a brown form; and sintering the brown form at a temperature in a range of about 1500 °C to about 1900 °C for a time period between about 3 hours to about 48 hours.

2. The method of claim 1 , further comprising mixing at least one precursor in a dispersant slurry, and tape casting the dispersant slurry to provide the green form.

3. The method of claim 1 or 2, further comprising bisque-firing the brown form at a temperature between about 800 °C to about 1400 °C for about 30 minutes to about 4 hours.

4. The method of claim 2 or 3, further comprising adding a sintering aid to the dispersant slurry.

5. The method of claim 1 , 2, 3, or 4, wherein the sintering is carried out without applying external force to the brown form.

6. A ceramic element prepared by the method of claim 1 , 2, 3, 4, or 5.

7. A ceramic element comprising a phosphor of Formula 1 :

8. The ceramic element of claim 7, which is in the form of a sintered ceramic plate.

9. The ceramic element of claim 7 or 8, wherein the sintered ceramic plate has a thickness of less than about 300 μιη.

10. The ceramic element of claim 7, 8, or 9, wherein x is a value in the range of 0.05 to 0.2.

1 1 . The ceramic element of claim 7, 8, 9, or 10, wherein m is a value in the range of 0.5 to 6.

12. The ceramic element of claim 7, 8, 9, 10, or 1 1 , wherein n is a value in the range of 0.5 to 5.

13. The ceramic element of claim 7, 8, 9, 10, 1 1 , 12, or 13, having an emissive peak at a wavelength between about 580 nm and about 620 nm.

14. The ceramic element of claim 7, 8, 9, 10, 1 1 , 12, or 13, which is emits orange light when excited by absorption visible light.

15. The ceramic element of claim 7, 8, 9, 10, 1 1 , 12, 13, or 14, wherein the phosphor of Formula 1 is at least about 90 vol% a-phase.

16. A lighting device comprising the ceramic element of claim 7, 8, 9, 10, 1 1 , 12, 13, 14, or 15 and an LED, wherein the element is applied directly upon the LED.

17. The lighting device of claim 16, wherein the LED is a blue LED.

18. The lighting device of claim 16 or 17, wherein the phosphor emits orange light, and the lighting device provides a soft white light.