NITROXIDE FLUORESCENT POWDER AND METHOD FOR PREPARING SAME, NITROXIDE ILLUMINANT, AND LUMINESCENT DEVICE

Abstract

The present invention discloses a nitroxide fluorescent powder comprising an inorganic compound containing M, A, B, O, N, and R elements; in which the M element is at least one of Ca, Sr, Ba, Mg, Li, Na, and K, the A element is at least one of B, Al, Ga, and In, the B element is at least one of C, Si, Ge, and Sn, the R element is at least one of Ce, Eu, Lu, Dy, Gd, and Ho, characterized in that the inorganic compound forms a crystal in a crystalline phase, and the oxygen atom content in the crystal in a crystalline phase is in an increasing structural distribution from a core to surface of the crystal. The nitroxide fluorescent powder and the nitroxide illuminant of the present invention have the advantages of good chemical stability, good aging and light decay resistance, and high luminescent efficiency, and are useful for various luminescent devices. The preparation method of the present invention is easy and reliable and useful for industrial mass production.

Claims

1. A nitroxide fluorescent powder comprising an inorganic compound containing M, A, B, O, N, and R elements; in which the M element is at least one of Ca, Sr, Ba, Mg, Li, Na, and K, the A element is at least one of B, Al, Ga, and In, the B element is at least one of C, Si, Ge, and Sn, the R element is at least one of Ce, Eu, Lu, Dy, Gd, and Ho, wherein the inorganic compound forms a crystal in a crystalline phase, and the oxygen atom content in the crystal in a crystalline phase is in an increasing structural distribution from a core to surface of the crystal.

2. The nitroxide fluorescent powder of claim 1, wherein the increasing structural distribution means that an inner core zone, a transition zone, and a crystal surface layer zone of the crystal in a crystalline phase are respectively formed depending on the distribution of the oxygen atom content in the crystal in a crystalline phase; the oxygen atom content in the inner core zone is in a gently increasing structural distribution from inside to outside, namely, the oxygen atom content in an outer surface of the inner core zone/the oxygen atom content in a core of the inner core zone 1.5; the oxygen atom content in the transition zone is in a dramatically increasing structural distribution from inside to outside, namely, the oxygen atom content in an outer surface of the transition zone/the oxygen atom content in an inner surface of the transition zone >1.5; the oxygen atom content in the surface layer zone is in a gently increasing structural distribution from inside to outside, namely, the oxygen atom content in an outer surface of the surface layer zone/the oxygen atom content in an inner surface of the surface layer zone 1.5.

3. The nitroxide fluorescent powder of claim 2, wherein the oxygen atom content in an outer surface of the transition zone/the oxygen atom content in an inner surface of the transition zone is >5.

4. The nitroxide fluorescent powder of claim 2, wherein in the crystal in a crystalline phase, the surface layer zone has a thickness of no more than 100 nm, the transition zone has a thickness of no more than 200 nm, and the inner core zone has a thickness from the inner surface of the transition zone to the core of the inner core zone.

5. The nitroxide fluorescent powder of claim 2, wherein the oxygen atom content in the core of the inner core zone is 10%; the oxygen atom content in the outer surface of the surface layer zone is 30%-50%.

6. The nitroxide fluorescent powder of claim 1, wherein the crystal in a crystalline phase formed by the inorganic compound has a chemical formula of Mm-rAaBbNnOc:Rr, in which 0.9m1.1, 0.8a1.2, 0.8b1.2, 2.5n3.5, 0.001c1, 0.001r0.1, and 2m+3a+4b3n2c=0 is met.

7. The nitroxide fluorescent powder of claim 1, wherein in the inorganic compound, M is one or a combination of Sr and Ca, A is Al, B is Si, and R is Eu.

8. The nitroxide fluorescent powder of claim 1, wherein the inorganic compound has the same crystal structure as the crystalline phase of CaAlSiN.sub.3.

9. The nitroxide fluorescent powder of claim 1, wherein the nitroxide fluorescent powder is excited at an excitation wavelength ranging from 300-500 nm to emit red light having a peak wavelength at 600-670 nm.

10. A nitroxide illuminant comprising a mixture of the nitroxide fluorescent powder of claim 1 and other crystalline grains or non-crystalline particles, the nitroxide fluorescent powder being present in the mixture at a proportion of no less than 50 wt %.

11. A method for preparing the nitroxide fluorescent powder of claim 1, wherein by comprising the following basic steps: step 1: weighting desired starting materials at a stoichiometric ratio of cations in the composition of a chemical formula M.sub.m-rA.sub.aB.sub.bO.sub.cN.sub.n:R.sub.r, with a nitride of M, a nitride of A, a nitride of B, and a nitride or oxide of R as starting materials, and uniformly mixing to form a mix; step 2: subjecting the mix obtained in the step 1 to high-temperature calcination in a calcination atmosphere, followed by low-temperature calcination at a reduced predetermined temperature in a nitrogen-oxygen mixture or air atmosphere, to give a nitroxide fluorescent powder semi-product; and step 3: subjecting the nitroxide fluorescent powder semi-product obtained in the step 2 to a post-treatment, to give a nitroxide fluorescent powder product.

12. A method for preparing the nitroxide fluorescent powder of claim 1, wherein by comprising the following basic steps: step 1: weighting desired starting materials at a stoichiometric ratio of cations in the composition of a chemical formula M.sub.m-rA.sub.aB.sub.bO.sub.cN.sub.n:R.sub.r, with a nitride of M, a nitride of A, a nitride of B, and a nitride or oxide of R as starting materials, and uniformly mixing to form a mix; step 2: subjecting the mix obtained in the step 1 to high-temperature calcination in a calcination atmosphere, to give a nitroxide fluorescent powder semi-product; step 3: subjecting the nitroxide fluorescent powder semi-product obtained in the step 2 to a post-treatment; and step 4: subjecting the nitroxide fluorescent powder semi-product obtained in the step 3 to low-temperature calcination in air, to give a nitroxide fluorescent powder product.

13. The method for preparing the nitroxide fluorescent powder of claim 11, characterized in that in the step 2, the high-temperature calcination has a temperature of 1600-2000 C. and a duration of 2-20 h, and the atmosphere of the high-temperature calcination is a pure nitrogen atmosphere or a reducing gas atmosphere; the low-temperature calcination has a temperature of 200-450 C. and a duration of 0.5-24 h, the volume percent of oxygen in the nitrogen-oxygen mixture atmosphere is no more than 20%.

14. (canceled)

15. The method for preparing the nitroxide fluorescent powder of claim 12, wherein in the step 2, the high-temperature calcination has a temperature of 1600-2000 C. and a duration of 2-20 h, and the atmosphere of the high-temperature calcination is a pure nitrogen atmosphere or a reducing gas atmosphere; in the step 4, the low-temperature calcination has a temperature of 200-450 C. and a duration of 0.5-24 h, and the atmosphere of the low-temperature calcination is an air atmosphere.

16. The method for preparing the nitroxide fluorescent powder of claim 11, wherein in the step 3, the post-treatment comprises primary grinding, screening, washing, drying, secondary grinding, and screening, and the washing is performed to obtain the nitroxide fluorescent powder having a conductivity of less than 10 s/cm.

17. The method for preparing the nitroxide fluorescent powder of claim 12, wherein in the step 3, the post-treatment comprises primary grinding, screening, washing, drying, secondary grinding, and screening, and the washing is performed to obtain the nitroxide fluorescent powder having a conductivity of less than 10 s/cm.

18. A luminescent device comprising an LED chip emitting UV light, violet light or blue light, and a fluorescent powder, wherein the fluorescent powder is a nitroxide fluorescent powder comprising an inorganic compound containing M, A, B, O, N, and R elements; in which the M element is at least one of Ca, Sr, Ba, Mg, Li, Na, and K, the A element is at least one of B, Al, Ga, and In, the B element is at least one of C, Si, Ge, and Sn, the R element is at least one of Ce, Eu, Lu, Dy, Gd, and Ho, characterized in that the inorganic compound forms a crystal in a crystalline phase, and the oxygen atom content in the crystal in a crystalline phase is in an increasing structural distribution from a core to surface of the crystal.

18. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG. 1 is a cross-sectional schematic view of a single crystal of a nitroxide fluorescent powder according to the present invention.

[0029] FIG. 2 is X-ray diffraction patterns of nitroxide fluorescent powder products in examples 1-4 of the present invention.

[0030] FIG. 3 is emission spectra of nitroxide fluorescent powder products in examples 5-8 of the present invention and a comparative example 2.

[0031] FIG. 4 is excitation spectra of the nitroxide fluorescent powder products in the examples 5-8 of the present invention and the comparative example 2.

[0032] FIG. 5 is an SEM picture of the nitroxide fluorescent powder product in the example 5 of the present invention.

[0033] FIG. 6 is an SEM picture of the nitroxide fluorescent powder product in the example 6 of the present invention.

[0034] FIG. 7 is an SEM picture of the nitroxide fluorescent powder product in the example 7 of the present invention.

[0035] FIG. 8 is an SEM picture of the nitroxide fluorescent powder product in the example 8 of the present invention.

[0036] FIG. 9 is emission spectra of nitroxide fluorescent powder products in examples 9-12 of the present invention and the comparative example 2.

[0037] FIG. 10 is emission spectra of nitroxide fluorescent powder products in examples 13-15 of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0038] A detailed description of the present invention will be further given below in detail with reference to the accompanying drawings and embodiments.

[0039] Referring to FIG. 1, a nitroxide fluorescent powder of the present invention is shown. The nitroxide fluorescent powder comprises an inorganic compound containing M, A, B, O, N, and R elements; in which the M element is at least one of Ca, Sr, Ba, Mg, Li, Na, and K, the A element is at least one of B, Al, Ga, and In, the B element is at least one of C, Si, Ge, and Sn, the R element is at least one of Ce, Eu, Lu, Dy, Gd, and Ho. The inorganic compound forms a crystal in a crystalline phase, and the oxygen atom content in the crystal in a crystalline phase is in an increasing structural distribution from a core to surface of the crystal.

[0040] Further preferred embodiments of a nitroxide fluorescent powder of the present invention include the following.

[0041] The increasing structural distribution means that an inner core zone, a transition zone, and a crystal surface layer zone of the crystal in a crystalline phase are respectively formed depending on the distribution of the oxygen atom content in the crystal in a crystalline phase; the oxygen atom content in the inner core zone is in a gently increasing structural distribution from inside to outside, namely, the oxygen atom content in an outer surface of the inner core zone/the oxygen atom content in a core of the inner core zone 1.5; the oxygen atom content in the transition zone is in a dramatically increasing structural distribution from inside to outside, namely, the oxygen atom content in an outer surface of the transition zone/the oxygen atom content in an inner surface of the transition zone >1.5; the oxygen atom content in the surface layer zone is in a gently increasing structural distribution from inside to outside, namely, the oxygen atom content in an outer surface of the surface layer zone/the oxygen atom content in an inner surface of the surface layer zone 1.5.

[0042] The oxygen atom content in an outer surface of the transition zone/the oxygen atom content in an inner surface of the transition zone is >5.

[0043] In the crystal in a crystalline phase, the surface layer zone has a thickness of no more than 100 nm, the transition zone has a thickness of no more than 200 nm, and the inner core zone has a thickness from the inner surface of the transition zone to the core of the inner core zone.

[0044] The oxygen atom content in the core of the inner core zone is 10%; the oxygen atom content in the outer surface of the surface layer zone is 30%-50%.

[0045] The crystal in a crystalline phase formed by the inorganic compound has a chemical formula of Mm-rAaBbNnOc:Rr, in which 0.9m1.1, 0.8a1.2, 0.8b1.2, 2.5n3.5, 0.001c1, 0.001r0.1, and 2m+3a+4b3n2c=0 is met.

[0046] In the inorganic compound, M is one or a combination of Sr and Ca, A is Al, B is Si, and R is Eu.

[0047] The inorganic compound has the same crystal structure as the crystalline phase of CaAlSiN.sub.3.

[0048] Any of the nitroxide fluorescent powders of the present invention as described above is excited at an excitation wavelength ranging from 300-500 nm to emit red light having a peak wavelength at 600-670 nm.

[0049] A method 1 for preparing a nitroxide fluorescent powder and preferred embodiments thereof according to the present invention comprises the following basic steps:

[0050] step 1: weighting desired starting materials at a stoichiometric ratio of cations in the composition of a chemical formula M.sub.m-rA.sub.aB.sub.bO.sub.cN.sub.n:R.sub.r, with a nitride of M, a nitride of A, a nitride of B, and a nitride or oxide of R as starting materials, and uniformly mixing to form a mix;

[0051] step 2: subjecting the mix obtained in the step 1 to high-temperature calcination in a calcination atmosphere, followed by low-temperature calcination at a reduced predetermined temperature in a nitrogen-oxygen mixture or air atmosphere, to give a nitroxide fluorescent powder semi-product; wherein the high-temperature calcination has a temperature of 1600-2000 C. and a duration of 2-20 h, and the atmosphere of the high-temperature calcination is a pure nitrogen atmosphere or a reducing gas atmosphere; the low-temperature calcination has a temperature of 200-450 C. and a duration of 0.5-24 h, and the volume percent of oxygen in the nitrogen-oxygen mixture atmosphere is no more than 20%; and

[0052] step 3: subjecting the nitroxide fluorescent powder semi-product obtained in the step 2 to a post-treatment, to give a nitroxide fluorescent powder product; wherein the post-treatment includes primary grinding, screening, washing, drying, secondary grinding, and screening, and the washing is performed to obtain the nitroxide fluorescent powder product having a conductivity of less than 10 s/cm.

[0053] A method 2 for preparing a nitroxide fluorescent powder and preferred embodiments thereof according to the present invention comprises the following basic steps:

[0054] step 1: weighting desired starting materials at a stoichiometric ratio of cations in the composition of a chemical formula M.sub.m-rA.sub.aB.sub.bO.sub.cN.sub.n:R.sub.r, with a nitride of M, a nitride of A, a nitride of B, and a nitride or oxide of R as starting materials, and uniformly mixing to form a mix;

[0055] step 2: subjecting the mix obtained in the step 1 to high-temperature calcination in a calcination atmosphere, to give a nitroxide fluorescent powder semi-product; wherein the high-temperature calcination has a temperature of 1600-2000 C. and a duration of 2-20 h, and the atmosphere of the high-temperature calcination is a pure nitrogen atmosphere or a reducing gas atmosphere;

[0056] step 3: subjecting the nitroxide fluorescent powder semi-product obtained in the step 2 to a post-treatment; wherein the post-treatment includes primary grinding, screening, washing, drying, secondary grinding, and screening, and the washing is performed to obtain the nitroxide fluorescent powder having a conductivity of less than 10 s/cm; and

[0057] step 4: subjecting the nitroxide fluorescent powder semi-product obtained in the step 3 to low-temperature calcination, to give a nitroxide fluorescent powder product; wherein the low-temperature calcination has a temperature of 200-450 C. and a duration of 0.5-24 h, and the atmosphere of the low-temperature calcination is an air atmosphere.

[0058] A luminescent device according to the present invention at least comprises an LED chip emitting UV light, violet light or blue light, and a fluorescent powder, wherein the fluorescent powder at least uses any of the nitroxide fluorescent powders of the present invention as described above.

[0059] Further preferably, a luminescent device according to the present invention further comprises other types of fluorescent powders, so as to meet lighting requirements or applications in high-color-rendering white light LEDs in the backlight, by complementation of luminescent colors.

[0060] Specific examples and comparative examples of a nitroxide fluorescent powder and method for preparing a same according to the present invention are further disclosed below, wherein the examples means that a nitroxide fluorescent powder product is obtained following a structure of a nitroxide fluorescent powder and method for preparing a same of the present invention, and the comparative examples means that a nitroxide fluorescent powder product is obtained following a nitroxide fluorescent powder and method for preparing a same disclosed in the prior art. The average oxygen atom content and the average nitrogen atom content in the fluorescent powders are obtained by an oxygen/nitrogen analyzer.

Example 1

[0061] 3.95 g of Ca.sub.3N.sub.2, 78.53 g of Sr.sub.3N.sub.2, 40.99 g of AlN, 46.76 g of Si.sub.3N.sub.4, and 3.52 g of Eu.sub.2O.sub.3 were weighted. These starting materials were thoroughly mixed in a nitrogen atmosphere for 3 h and charged into an Mo crucible, which was rapidly transferred to a tubular furnace, and then the temperature was gradually raised to 1780 C. under a hydrogen atmosphere for 12 h; and then the temperature was reduced to 450 C. at 10 C./min, and a mixture gas of nitrogen and oxygen of 90%10% by volume was fed for calcination for 0.5 h; the resulting luminescent particle was pulverized and sieved, the sieved particle was placed into deionized water and stirred for 30 min, then suction-filtered, and finally washed to a conductivity of 8.56 s/cm, to give a nitroxide fluorescent powder particle product. The X-ray diffraction pattern is shown in FIG. 2, the composition of the fluorescent powder crystal is Sr.sub.0.9Ca.sub.0.08AlSiN.sub.2.84O.sub.0.22:Eu.sub.0.02, and as measured by auger electron spectroscopy coupled with ion etching, the surface layer zone of the crystal has a thickness of 30 nm, the transition zone of the crystal has a thickness of 50 nm, the oxygen atom content in the core of the inner core zone of the crystal is 3.3%, the oxygen atom content in the inner surface of the transition zone of the crystal is 4.2%, the oxygen atom content in the outer surface of the transition zone of the crystal is 22%, and the oxygen atom content in the outer surface of the surface layer zone of the crystal is 31%.

Example 2

[0062] 43.98 g of Ca.sub.3N.sub.2, 7.76 g of Sr.sub.3N.sub.2, 40.99 g of AlN, 46.76 g of Si.sub.3N.sub.4, and 5.28 g of Eu.sub.2O.sub.3 were weighted. These starting materials were thoroughly mixed in a nitrogen atmosphere for 3 h and charged into an Mo crucible, which was rapidly transferred to a carbon tube furnace, and then the temperature was gradually raised to 2000 C. under a pure nitrogen atmosphere for 2 h; and then the temperature was reduced to 300 C. at 8 C./min, and a mixture gas of nitrogen and oxygen of 80%:20% by volume was fed for calcination for 24 h; the resulting fluorescent powder particle was pulverized and sieved, the sieved particle was placed into deionized water and stirred for 30 min, then suction-filtered, and finally washed to a conductivity of 8.89 s/cm, to give a nitroxide fluorescent powder particle product. The X-ray diffraction pattern is shown in FIG. 2, the composition of the fluorescent powder is Sr.sub.0.08Ca.sub.0.89AlSiN.sub.2.92O.sub.0.12:Eu.sub.0.03, and as measured by auger electron spectroscopy coupled with ion etching, the surface layer zone of the crystal has a thickness of 99 nm, the transition zone of the crystal has a thickness of 198 nm, the oxygen atom content in the core of the inner core zone of the crystal is 1.6%, the oxygen atom content in the inner surface of the transition zone of the crystal is 2%, the oxygen atom content in the outer surface of the transition zone of the crystal is 30%, and the oxygen atom content in the outer surface of the surface layer zone of the crystal is 49%.

Example 3

[0063] 46.95 g of Ca.sub.3N.sub.2, 40.99 g of AlN, 46.76 g of Si.sub.3N.sub.4, and 8.8 g of Eu.sub.2O.sub.3 were weighted. These starting materials were thoroughly mixed in a nitrogen atmosphere for 3 h and charged into an Mo crucible, which was rapidly transferred to a tubular furnace, and then the temperature was gradually raised to 1600 C. under a CO atmosphere for 20 h; and then the temperature was reduced to 320 C. at 10 C./min, and a mixture gas of nitrogen and oxygen of 95%:5% by volume was fed for calcination for 1 h; the sieved fluorescent powder particle was placed into deionized water and stirred for 30 min, then suction-filtered, and finally washed to a conductivity of 9.52 s/cm, to give a nitroxide fluorescent powder particle product. The X-ray diffraction pattern is shown in FIG. 2, the composition of the fluorescent powder crystal is Ca.sub.0.95AlSiN.sub.2.84O.sub.0.24:Eu.sub.0.05, and as measured by auger electron spectroscopy coupled with ion etching, the surface layer zone of the crystal has a thickness of 9 nm, the transition zone of the crystal has a thickness of 30 nm, the oxygen atom content in the core of the inner core zone of the crystal is 2.8%, the oxygen atom content in the inner surface of the transition zone of the crystal is 3.6%, the oxygen atom content in the outer surface of the transition zone of the crystal is 22%, and the oxygen atom content in the outer surface of the surface layer zone of the crystal is 30%.

Example 4

[0064] 9.39 g of Ca.sub.3N.sub.2, 77.57 g of Sr.sub.3N.sub.2, 40.99 g of AlN, 46.76 g of Si.sub.3N.sub.4, and 1.76 g of Eu.sub.2O.sub.3 were weighted. These starting materials were thoroughly mixed in a nitrogen atmosphere for 3 h and charged into an Mo crucible, which was rapidly transferred to a carbon tube furnace, and then the temperature was gradually raised to 1870 C. under a pure nitrogen atmosphere for 10 h; and then the temperature was reduced to 400 C. at 7 C./min, and a mixture gas of nitrogen and oxygen of 96%:4% by volume was fed for calcination for 3 h; the resulting fluorescent powder particle was pulverized and sieved, the sieved fluorescent powder particle was placed into deionized water and stirred for 30 min, then suction-filtered, and finally washed to a conductivity of 9.45 s/cm, to give a nitroxide fluorescent powder particle product. The X-ray diffraction pattern is shown in FIG. 2, the composition of the fluorescent powder crystal is Sr.sub.0.8Ca.sub.0.19AlSiN.sub.2.86O.sub.0.21:Eu.sub.0.01, and as measured by auger electron spectroscopy coupled with ion etching, the surface layer zone of the crystal has a thickness of 35 nm, the transition zone of the crystal has a thickness of 70 nm, the oxygen atom content in the core of the inner core zone of the crystal is 2.5%, the oxygen atom content in the inner surface of the transition zone of the crystal is 3.5%, the oxygen atom content in the outer surface of the transition zone of the crystal is 30%, and the oxygen atom content in the outer surface of the surface layer zone of the crystal is 35%.

Comparative Example 1

[0065] 3.95 g of Ca.sub.3N.sub.2, 87.26 g of Sr.sub.3N.sub.2, 40.99 g of AlN, 46.76 g of Si.sub.3N.sub.4, and 3.52 g of Eu.sub.2O.sub.3 were weighted. These starting materials were thoroughly mixed in a nitrogen atmosphere for 3 h and charged into an Mo crucible, which was rapidly transferred to a carbon tube furnace, and then the temperature was gradually raised to 1800 C. under a pure nitrogen atmosphere for 12 h; the resulting fluorescent powder particle was pulverized and sieved, the sieved fluorescent powder particle was placed into deionized water and stirred for 30 min, then suction-filtered, and finally washed to a conductivity of 7.12 s/cm, to give a fluorescent powder particle product. The composition of the fluorescent powder is Sr.sub.0.9Ca.sub.0.08AlSiN.sub.3:Eu.sub.0.02.

[0066] The fluorescent powder particles in the examples and the comparative example as described above were made into a luminescent device respectively, and the testing results show that the luminescent intensity and the aging properties of the comparative example 1 are lower than those of the examples 1-4, as shown in Table 1. The aging conditions are: SMD 2835 LED Lamp Bead, chip size 1030 mil, chip band 452.5-455 nm, current 150 mA, power 0.5 W, ambient conditions: normal temperature and moisture.

TABLE-US-00001 TABLE 1 luminescent 1000 h aging intensity light decay X Y Example 1 103 2.7% 0.008 0.009 Example 2 104 2.05% 0.005 0.005 Example 3 102 3.2% 0.009 0.010 Example 4 101 2.5% 0.06 0.008 Comparative 100 5.6% 0.028 0.017 example 1

Example 5

[0067] 12.85 g of Ca.sub.3N.sub.2, 67.87 g of Sr.sub.3N.sub.2, 36.89 g of AlN, 42.08 g of Si.sub.3N.sub.4, 1.76 g of Eu.sub.2O.sub.3, 1.48 g of Li.sub.2CO.sub.3, 11.17 g of GaN.sub.3, and 27.4 g of Ge.sub.3N.sub.4 were weighted. These starting materials were thoroughly mixed in a nitrogen atmosphere for 3 h and charged into an Mo crucible, which was rapidly transferred to a carbon tube furnace, and then the temperature was gradually raised to 1690 C. under a pure nitrogen atmosphere for 19 h; and then the temperature was reduced to 200 C. at 6 C./min, and a mixture gas of nitrogen and oxygen of 97%:3% by volume was fed for calcination for 15 h; the resulting fluorescent powder particle was pulverized and sieved, the sieved fluorescent powder particle was placed into deionized water and stirred for 30 min, then suction-filtered, and finally washed to a conductivity of 9.5 s/cm, to give a nitroxide fluorescent powder particle product. The emission spectrum is shown in FIG. 3, the excitation spectrum is shown in FIG. 4, the SEM picture is shown in FIG. 5, the composition of the fluorescent powder crystal is Li.sub.0.06Sr.sub.0.08Ca.sub.0.89Al.sub.0.9Ga.sub.0.1Si.sub.0.9Ge.sub.0.1N.sub.2.88O.sub.0.15:Eu.sub.0.01, and as measured by auger electron spectroscopy coupled with ion etching, the surface layer zone of the crystal has a thickness of 15 nm, the transition zone of the crystal has a thickness of 42 nm, the oxygen atom content in the core of the inner core zone of the crystal is 1.8%, the oxygen atom content in the inner surface of the transition zone of the crystal is 2%, the oxygen atom content in the outer surface of the transition zone of the crystal is 37%, and the oxygen atom content in the outer surface of the surface layer zone of the crystal is 42%.

Example 6

[0068] 24.71 g of Ca.sub.3N.sub.2, 38.78 g of Sr.sub.3N.sub.2, 40.998 g of AlN, 46.76 g of Si.sub.3N.sub.4, 8.8 g of Eu.sub.2O.sub.3, and 7.66 g of BaO were weighted. These starting materials were thoroughly mixed in a nitrogen atmosphere for 3 h and charged into an Mo crucible, which was rapidly transferred to a carbon tube furnace, and then the temperature was gradually raised to 1790 C. under a nitrogen atmosphere for 18 h; and then the temperature was reduced to 300 C. at 7 C./min, and air was fed for calcination for 6 h; the resulting fluorescent powder particle was pulverized and sieved, the sieved fluorescent powder particle was placed into deionized water and stirred for 30 min, then suction-filtered, and finally washed to a conductivity of 7.5 s/cm, to give a nitroxide fluorescent powder particle product. The emission spectrum is shown in FIG. 3, the excitation spectrum is shown in FIG. 4, the SEM picture is shown in FIG. 6, the composition of the fluorescent powder crystal is Ba.sub.0.05Sr.sub.0.4Ca.sub.0.5AlSiN.sub.2.76O.sub.0.24:Eu.sub.0.05, and as measured by auger electron spectroscopy coupled with ion etching, the surface layer zone of the crystal has a thickness of 25 nm, the transition zone of the crystal has a thickness of 45 nm, the oxygen atom content in the core of the inner core zone of the crystal is 3.2%, the oxygen atom content in the inner surface of the transition zone of the crystal is 3.9%, the oxygen atom content in the outer surface of the transition zone of the crystal is 29%, and the oxygen atom content in the outer surface of the surface layer zone of the crystal is 33%.

Example 7

[0069] 9.88 g of Ca.sub.3N.sub.2, 58.18 g of Sr.sub.3N.sub.2, 32.8 g of AlN, 37.4 g of Si.sub.3N.sub.4, 3.52 g of Eu.sub.2O.sub.3, 7.25 g of MgO, 31.37 g of InN.sub.3, and 82.43 g Sn.sub.3N.sub.4 were weighted. These starting materials were thoroughly mixed in a nitrogen atmosphere for 3 h and charged into an Mo crucible, which was rapidly transferred to a carbon tube furnace, and then the temperature was gradually raised to 1780 C. under a pure nitrogen atmosphere for 15 h; and the resulting fluorescent powder particle was pulverized and sieved, the sieved fluorescent powder particle was placed into deionized water and stirred for 30 min, then suction-filtered, and finally washed to a conductivity of 6.9 s/cm; and then it was placed in an oven at 450 C. for calcination for 0.5 h, and after sieving, a nitroxide fluorescent powder particle product was obtained. The emission spectrum is shown in FIG. 3, the excitation spectrum is shown in FIG. 4, the SEM picture is shown in FIG. 7, the composition of the fluorescent powder crystal is Mg.sub.0.2Sr.sub.0.6Ca.sub.0.18Al.sub.0.8In.sub.0.2Si.sub.0.8Sn.sub.0.2N.sub.2.76O.sub.0.18:Eu.sub.0.02, and as measured by auger electron spectroscopy coupled with ion etching, the surface layer zone of the crystal has a thickness of 23 nm, the transition zone of the crystal has a thickness of 72 nm, the oxygen atom content in the core of the inner core zone of the crystal is 2.6%, the oxygen atom content in the inner surface of the transition zone of the crystal is 3.5%, the oxygen atom content in the outer surface of the transition zone of the crystal is 38%, and the oxygen atom content in the outer surface of the surface layer zone of the crystal is 41%.

Example 8

[0070] 2.22 g of Ca.sub.3N.sub.2, 89.2 g of Sr.sub.3N.sub.2, 40.998 g of AlN, 46.76 g of Si.sub.3N.sub.4, 3.52 g of Eu.sub.2O.sub.3, and 3.73 g of Dy.sub.2O.sub.3 were weighted. These starting materials were thoroughly mixed in a nitrogen atmosphere for 3 h and charged into an Mo crucible, which was rapidly transferred to a carbon tube furnace, and then the temperature was gradually raised to 1750 C. under a nitrogen atmosphere for 10 h; and the resulting fluorescent powder particle was pulverized and sieved, the sieved nitroxide fluorescent powder particle was placed into deionized water and stirred for 30 min, then suction-filtered, and finally washed to a conductivity of 9.8 s/cm; and then it was placed in an oven at 280 C. for calcination for 18 h, and after sieving, a nitroxide fluorescent powder particle product was obtained. The emission spectrum is shown in FIG. 3, the excitation spectrum is shown in FIG. 4, the SEM picture is shown in FIG. 8, the structural formula of the fluorescent powder crystal is Dy.sub.0.01Sr.sub.0.92Ca.sub.0.45AlSiN.sub.2.85O.sub.0.21:Eu.sub.0.02, and as measured by auger electron spectroscopy coupled with ion etching, the surface layer zone of the crystal has a thickness of 87 nm, the transition zone of the crystal has a thickness of 14 nm, the oxygen atom content in the core of the inner core zone of the crystal is 2.5%, the oxygen atom content in the inner surface of the transition zone of the crystal is 3.6%, the oxygen atom content in the outer surface of the transition zone of the crystal is 36%, and the oxygen atom content in the outer surface of the surface layer zone of the crystal is 45%.

Comparative Example 2

[0071] 2.22 g of Ca.sub.3N.sub.2, 89.2 g of Sr.sub.3N.sub.2, 40.998 g of AlN, 46.76 g of Si.sub.3N.sub.4, 3.52 g of Eu.sub.2O.sub.3, and 3.73 g of Dy.sub.2O.sub.3 were weighted. These starting materials were thoroughly mixed in a nitrogen atmosphere for 3 h and charged into an Mo crucible, which was rapidly transferred to a tubular furnace, and then the temperature was gradually raised to 1750 C. under a pure nitrogen atmosphere for 15 h; the resulting fluorescent powder particle was pulverized and sieved, the sieved fluorescent powder particle was placed into deionized water and stirred for 30 min, then suction-filtered, and finally washed to a conductivity of 8.12 s/cm, to give a fluorescent powder particle product. The emission spectrum is shown in FIG. 3, the excitation spectrum is shown in FIG. 4, and the composition of the fluorescent powder is Sr.sub.0.92Ca.sub.0.045AlSiN.sub.3:Eu.sub.0.02Dy.sub.0.01.

[0072] The fluorescent powder particles in the examples and the comparative example as described above were made into a luminescent device respectively, and the testing results show that the luminescent intensity and the aging properties of the comparative example 2 are lower than those of the examples 5-8, as shown in Table 2. The aging conditions are: SMD 2835 LED Lamp Bead, chip size 1030 mil, chip band 452.5-455 nm, current 150 mA, power 0.5 W, ambient conditions: normal temperature and moisture.

TABLE-US-00002 TABLE 2 luminescent 1000 h aging intensity light decay X Y Example 5 101 3.0% 0.0010 0.0010 Example 6 102 2.9% 0.007 0.009 Example 7 100.3 2.7% 0.006 0.008 Example 8 102 2.4% 0.06 0.008 Comparative 100 6.3% 0.038 0.027 example 2

Example 9

[0073] 7.1 g of Ba.sub.3N.sub.2, 2.47 g of Ca.sub.3N.sub.2, 77.56 g of Sr.sub.3N.sub.2, 2.015 g of MgO, 49.19 g of AlN, 37.41 g of Si.sub.3N.sub.4, 3.52 g of Eu.sub.2O.sub.3, 1.99 g of Lu.sub.2O.sub.3, and 1.89 g of Ho.sub.2O.sub.3 were weighted. These starting materials were thoroughly mixed in a nitrogen atmosphere for 3 h and charged into an Mo crucible, which was rapidly transferred to a carbon tube furnace, and then the temperature was gradually raised to 1870 C. under a pure nitrogen atmosphere for 10 h; and the resulting fluorescent powder particle was pulverized and sieved, the sieved fluorescent powder particle was placed into deionized water and stirred for 30 min, then suction-filtered, and finally washed to a conductivity of 9.8 s/cm; and then it was placed in an oven at 300 C. for calcination for 12 h, and after sieving, a nitroxide fluorescent powder particle product was obtained. The emission spectrum is shown in FIG. 9, the composition of the fluorescent powder crystal is Sr.sub.0.8Ca.sub.0.005Ba.sub.0.05Mg.sub.0.05Al.sub.1.2Si.sub.0.8N.sub.2.71O.sub.0.33:Eu.sub.0.02Lu.sub.0.01Ho.sub.0.01, and as measured by auger electron spectroscopy coupled with ion etching, the surface layer zone of the crystal has a thickness of 56 nm, the transition zone of the crystal has a thickness of 24 nm, the oxygen atom content in the core of the inner core zone of the crystal is 4%, the oxygen atom content in the inner surface of the transition zone of the crystal is 5.6%, the oxygen atom content in the outer surface of the transition zone of the crystal is 33%, and the oxygen atom content in the outer surface of the surface layer zone of the crystal is 39%.

Example 10

[0074] 4.45 g of Ca.sub.3N.sub.2, 67.87 g of Sr.sub.3N.sub.2, 0.37 g of Li.sub.2CO.sub.3, 32.79 g of AlN, 56.11 g of Si.sub.3N.sub.4, 15.84 g of Eu.sub.2O.sub.3, and 1.81 g of Gd.sub.2O.sub.3 were weighted. These starting materials were thoroughly mixed in a nitrogen atmosphere for 3 h and charged into an Mo crucible, which was rapidly transferred to a carbon tube furnace, and then the temperature was gradually raised to 1780 C. under a pure nitrogen atmosphere for 8 h; and the resulting fluorescent powder particle was pulverized and sieved, the sieved fluorescent powder particle was placed into deionized water and stirred for 30 min, then suction-filtered, and finally washed to a conductivity of 5.7 us/cm; and then it was placed in an oven at 350 C. for calcination for 2 h, and after sieving, a nitroxide fluorescent powder particle product was obtained. The emission spectrum is shown in FIG. 9, the composition of the fluorescent powder is Li.sub.0.01Ca.sub.0.09Sr.sub.0.7Al.sub.0.8Si.sub.1.2N.sub.2.68O.sub.0.48:Eu.sub.0.09Gd.sub.0.01, and as measured by auger electron spectroscopy coupled with ion etching, the surface layer zone of the crystal has a thickness of 34 nm, the transition zone of the crystal has a thickness of 14 nm, the oxygen atom content in the core of the inner core zone of the crystal is 6.5%, the oxygen atom content in the inner surface of the transition zone of the crystal is 8.2%, the oxygen atom content in the outer surface of the transition zone of the crystal is 25%, and the oxygen atom content in the outer surface of the surface layer zone of the crystal is 35%.

Example 11

[0075] 32.12 g of Ca.sub.3N.sub.2, 38.78 g of Sr.sub.3N.sub.2, 0.69 g of K.sub.2CO.sub.3, 45.09 g of AlN, 42.08 g of Si.sub.3N.sub.4, 5.28 g of Eu.sub.2O.sub.3, and 1.54 g of CeN were weighted. These starting materials were thoroughly mixed in a nitrogen atmosphere for 3 h and charged into an Mo crucible, which was rapidly transferred to a carbon tube furnace, and then the temperature was gradually raised to 1680 C. under a pure nitrogen atmosphere for 19 h; and the resulting fluorescent powder particle was pulverized and sieved, the sieved fluorescent powder particle was placed into deionized water and stirred for 30 min, then suction-filtered, and finally washed to a conductivity of 6.9 us/cm; and then it was placed in an oven at 400 C. for calcination for 13 h, and after sieving, a nitroxide fluorescent powder particle product was obtained. The emission spectrum is shown in FIG. 9, the composition of the fluorescent powder is K.sub.0.01Ca.sub.0.65Sr.sub.0.4Al.sub.0.9Si.sub.1.1N.sub.2.85O.sub.0.27:Eu.sub.0.03Ce.sub.0.01, and as measured by auger electron spectroscopy coupled with ion etching, the surface layer zone of the crystal has a thickness of 102 nm, the transition zone of the crystal has a thickness of 56 nm, the oxygen atom content in the core of the inner core zone of the crystal is 3.7%, the oxygen atom content in the inner surface of the transition zone of the crystal is 4.8%, the oxygen atom content in the outer surface of the transition zone of the crystal is 37%, and the oxygen atom content in the outer surface of the surface layer zone of the crystal is 42%.

Example 12

[0076] 32.12 g of Ca.sub.3N.sub.2, 38.78 g of Sr.sub.3N.sub.2, 0.69 g of K.sub.2CO.sub.3, 36.89 g of AlN, 2.48 g of BN, 83.73 g of GaN, 42.08 g of Si.sub.3N.sub.4, 5.28 g of Eu.sub.2O.sub.3, and 1.54 g of CeN were weighted. These starting materials were thoroughly mixed in a nitrogen atmosphere for 3 h and charged into an Mo crucible, which was rapidly transferred to a carbon tube furnace, and then the temperature was gradually raised to 1600 C. under a pure nitrogen atmosphere for 20 h; and the resulting fluorescent powder particle was pulverized and sieved, the sieved fluorescent powder particle was placed into deionized water and stirred for 30 min, then suction-filtered, and finally washed to a conductivity of 6.9 s/cm; and then it was placed in an oven at 200 C. for calcination for 24 h, and after sieving, a nitroxide fluorescent powder particle product was obtained. The emission spectrum is shown in FIG. 9, the composition of the fluorescent powder is K.sub.0.01Ca.sub.0.65Sr.sub.0.4Al.sub.0.9B.sub.0.1Ga.sub.0.1Si.sub.0.9N.sub.2.85O.sub.0.27:Eu.sub.0.03Ce.sub.0.01, and as measured by auger electron spectroscopy coupled with ion etching, the surface layer zone of the crystal has a thickness of 67 nm, the transition zone of the crystal has a thickness of 56 nm, the oxygen atom content in the core of the inner core zone of the crystal is 3.6%, the oxygen atom content in the inner surface of the transition zone of the crystal is 4.2%, the oxygen atom content in the outer surface of the transition zone of the crystal is 37%, and the oxygen atom content in the outer surface of the surface layer zone of the crystal is 42%.

Example 13

[0077] 5.44 g of Ca.sub.3N.sub.2, 82.41 g of Sr.sub.3N.sub.2, 36.89 g of AlN, 9.13 g of Ge.sub.3N.sub.4, 13.74 g of Sn.sub.3N.sub.4, 42.08 g of Si.sub.3N.sub.4, and 7.04 g of Eu.sub.3O.sub.3 were weighted. These starting materials were thoroughly mixed in a nitrogen atmosphere for 3 h and charged into an Mo crucible, which was rapidly transferred to a carbon tube furnace, and then the temperature was gradually raised to 1680 C. under a pure nitrogen atmosphere for 19 h; and the resulting fluorescent powder particle was pulverized and sieved, the sieved fluorescent powder particle was placed into deionized water and stirred for 30 min, then suction-filtered, and finally washed to a conductivity of 6.9 s/cm; and then it was placed in an oven at 380 C. for calcination for 10 h, and after sieving, a nitroxide fluorescent powder particle product was obtained. The emission spectrum is shown in FIG. 10, the composition of the fluorescent powder is Ca.sub.0.11Sr.sub.0.85Al.sub.0.9Ge.sub.0.1Sn.sub.0.1Si.sub.0.9N.sub.2.57O.sub.0.3:Eu.sub.0.04, and as measured by auger electron spectroscopy coupled with ion etching, the surface layer zone of the crystal has a thickness of 87 nm, the transition zone of the crystal has a thickness of 102 nm, the oxygen atom content in the core of the inner core zone of the crystal is 4.2%, the oxygen atom content in the inner surface of the transition zone of the crystal is 5.2%, the oxygen atom content in the outer surface of the transition zone of the crystal is 35%, and the oxygen atom content in the outer surface of the surface layer zone of the crystal is 44%.

Example 14

[0078] 4.89 g of Ca.sub.3N.sub.2, 95.99 g of Sr.sub.3N.sub.2, 47.5 g of AlN, 56.1 g of Si.sub.3N.sub.4, and 0.17 g of EuN were weighted. These starting materials were thoroughly mixed in a nitrogen atmosphere for 3 h and charged into an Mo crucible, which was rapidly transferred to a carbon tube furnace, and then the temperature was gradually raised to 1730 C. under a pure nitrogen atmosphere for 19 h; and the resulting fluorescent powder particle was pulverized and sieved, the sieved fluorescent powder particle was placed into deionized water and stirred for 30 min, then suction-filtered, and finally washed to a conductivity of 8.5 s/cm; and then it was placed in an oven at 250 C. for calcination for 2 h, and after sieving, a nitroxide fluorescent powder particle product was obtained. The emission spectrum is shown in FIG. 10, the composition of the fluorescent powder is Ca.sub.0.099Sr.sub.0.99Al.sub.1.16Si.sub.1.2N.sub.3.47O.sub.0.03:Eu.sub.0.001, and as measured by auger electron spectroscopy coupled with ion etching, the surface layer zone of the crystal has a thickness of 25 nm, the transition zone of the crystal has a thickness of 9 nm, the oxygen atom content in the core of the inner core zone of the crystal is 0.4%, the oxygen atom content in the inner surface of the transition zone of the crystal is 0.6%, the oxygen atom content in the outer surface of the transition zone of the crystal is 10%, and the oxygen atom content in the outer surface of the surface layer zone of the crystal is 14%.

Example 15

[0079] 9.88 g of Ca.sub.3N.sub.2, 71.75 g of Sr.sub.3N.sub.2, 19.68 g of AlN, 20.39 g of Al.sub.2O.sub.3, 37.4 g of Si.sub.3N.sub.4, and 10.56 g of EuN were weighted. These starting materials were thoroughly mixed in a nitrogen atmosphere for 3 h and charged into an Mo crucible, which was rapidly transferred to a carbon tube furnace, and then the temperature was gradually raised to 1690 C. under a pure nitrogen atmosphere for 20 h; and the resulting fluorescent powder particle was pulverized and sieved, the sieved fluorescent powder particle was placed into deionized water and stirred for 30 min, then suction-filtered, and finally washed to a conductivity of 8.7 s/cm; and then it was placed in an oven at 290 C. for calcination for 17 h, and after sieving, a nitroxide fluorescent powder particle product was obtained. The emission spectrum is shown in FIG. 10, the composition of the fluorescent powder is Ca.sub.0.2Sr.sub.0.74Al.sub.0.8Si.sub.0.8N.sub.2.2O.sub.0.5:Eu.sub.0.06, and as measured by auger electron spectroscopy coupled with ion etching, the surface layer zone of the crystal has a thickness of 38 nm, the transition zone of the crystal has a thickness of 125 nm, the oxygen atom content in the core of the inner core zone of the crystal is 9%, the oxygen atom content in the inner surface of the transition zone of the crystal is 12.5%, the oxygen atom content in the outer surface of the transition zone of the crystal is 40%, and the oxygen atom content in the outer surface of the surface layer zone of the crystal is 48%.

[0080] The fluorescent powder particles in the examples and the comparative example 2 as described above were made into a luminescent device respectively, and the testing results show that the luminescent intensity and the aging properties of the comparative example 2 are lower than those of the examples 9-15, as shown in Table 3. The aging conditions are: SMD 2835 LED Lamp Bead, chip size 1030 mil, chip band 452.5-455 nm, current 150 mA, power 0.5 W, ambient conditions: normal temperature and moisture.

TABLE-US-00003 TABLE 3 luminescent 1000 h aging intensity light decay X Y Example 9 100.1 2.5% 0.008 0.009 Example 10 100.5 3.2% 0.0010 0.0011 Example 11 100.2 2.4% 0.005 0.006 Example 12 102 2.3% 0.06 0.007 Example 13 101 2.5% 0.06 0.008 Example 14 101 3.1% 0.05 0.008 Example 15 102 2.2% 0.04 0.006 comparative 100 6.3% 0.038 0.027 example 2

[0081] The contents not specifically described in the specific embodiments of the present invention are known in the art and may be implemented with reference to known techniques.

[0082] The present invention has been verified via repeated tests, and satisfactory test results are achieved.

[0083] The specific embodiments and examples above are provided to support the technical concepts of a nitroxide fluorescent powder and method for preparing a same, a nitroxide illuminant, and a luminescent device of the present invention, and are not intended to limit the scope of protection of the present invention. Any equivalent modification or variations made based on the present technical solution following the technical concepts of the present invention, all fall within the scope of protection of the present invention.