KR100687131B1 - Blue Phosphor for Plasma Display and Lamp Applications and Method of Making - Google Patents

Abstract

Stable complexes or phosphor blend is active chain Tm ^3+, Li ^+, and any optional amount of the auxiliary active chain 1 kinds of alkaline earth elements (AE ²⁺⁾ and the empirical formula _{(La 1-xyz Tm x Li} y AE z) PO 4 ( Lanthanum phosphate phosphor represented by 0.001 ≦ x ≦ 0.05, 0.01 ≦ y ≦ 0.05, and 0 ≦ z ≦ 0.05), and 15 to 30% by weight of (i) empirical formula (Ba _1-x Eu _x ) OMg _y O Barium magnesium aluminate (BAM) activated with a divalent europium represented by (Al ₂ O ₃ ) _z (wherein 0.005 ≦ x ≦ 0.05, 1 ≦ y ≦ 2, and 5 ≦ _z ≦ 7); Or (ii) empirical formula (Ba _1-x Eu _x ) OMg _y O (Al _2-v La _v O ₃ ) _z (wherein 0.005 ≦ _x ≦ 0.05, ₁ ≦ _y ≦ ₂ , 5 ≦ _z ≦ 7 and 0.1 ≦ barium lanthanum magnesium aluminate (BLMA) activated with a divalent europium represented by v ≦ 1; Or (iii) empirical formula (x.Sr, y.Ba, z.Cz, u.Mg) ₅ (PO ₄ ) ₃ Cl (where x + y + z + u = 0.1, 0 ≦ x ≦ 1.0, 0 ≦ alkaline earth chloro apatite activated by divalent europium represented by y ≦ 1.0, 0 ≦ z ≦ 1.0 and 0 ≦ u ≦ 1.0 (AECAP); Or (iv) calcium chloro borate (CCB) activated with divalent europium represented by the empirical formula (Ca _5-x Eu _x ) B ₅ O ₉ Cl (wherein 0.005≤x≤0.05).

Lanthanum phosphate phosphor, barium magnesium aluminate, barium lanthanum magnesium aluminate, alkaline earth chloro apatite, calcium chloro borate

Description

Blue Phosphor for Plasma Display and Lamp Applications and Method of Making}

1 shows the X-ray diffraction pattern of the LaPO ₄ : Tm, Li phosphor.

FIG. 2A shows the particle size distribution of LaPO ₄ : Tm, Li phosphors prepared by the sol-gel / xerogel method.

FIG. 2B shows the particle size distribution of the LaPO ₄ : Tm, Li phosphor produced by the solid state method.

3A and 3B provide spectral distributions of radiant energy from xenon lamps equipped with MgF ₂ windows and a suitable bandpass filter ((a) 147 nm and (b) wavelengths of 173 nm).

4 shows the emission spectrum of the LaPO ₄ : Tm, Li phosphor at 147 nm excited state.

FIG. 5 shows the emission spectrum of the LaPO ₄ : Tm, Li phosphor at 173 nm excited state.

FIG. 6 shows BaMg ₂ Al ₁₀ O ₁₇ (BAM) or BaMg ₂ Al ₁₆ O ₂₇ activated with LaPO ₄ : Tm, Li (LPT) at 147 nm excited and 75% LPT and 25% divalent europium. BAM2) or BaMgLaAl ₉ O ₁₇ (BLMA) or Sr ₅ (PO ₃ ) ₃ Cl (SCAP) or (Sr, Ca, Ba, Mg) ₅ (PO ₄ ) ₃ Cl (BSCMCAP) or Ca ₅ B ₅ O ₉ Cl The emission spectrum of the phosphor blend made with (CCB) is shown.

FIG. 7 shows BaMg ₂ Al ₁₀ O ₁₇ (BAM) or BaMg ₂ Al ₁₆ O ₂₇ activated with LaPO ₄ : Tm, Li (LPT) with 173 nm excited and 75% LPT and 25% divalent europium. BAM2) or BaMgLaAl ₉ O ₁₇ (BLMA) or Sr ₅ (PO ₃ ) ₃ Cl (SCAP) or (Sr, Ca, Ba, Mg) ₅ (PO ₄ ) ₃ Cl (BSCMCAP) or Ca ₅ B ₅ O ₉ Cl The emission spectrum of the phosphor blend made with (CCB) is shown.

FIELD OF THE INVENTION The present invention relates to an improved blue emitting phosphor complex or blend, and more particularly to a first phosphor that is excited from a vacuum UV (VUV) light source and then emits both ultraviolet (UV) and visible light and by both VUV and UV. A complexing phosphor mixture comprising a second phosphor which can be employed.

Background of the Invention

Plasma display panels (PDPs) used in direct television and high resolution television applications typically use a bivalent europium activated barium magnesium aluminate (BAM) phosphor as a blue emitting component due to its availability and high quantum efficiency. . However, when compared to other phosphors such as yttrium activated with Eu ³⁺ (red) and Tb ³⁺ (green), gadolinium borate-based phosphors or zinc silicates activated with Mn, BAM has poor color purity under VUV flux. Emits a broad spectrum and has a low lifespan.

The lifetime of a plasma display is directly related to the performance of the phosphor used in the display. Therefore, the lifetime of the phosphor is an important issue in the selection of a suitable phosphor. In other words, displays for home and industrial applications should have a working life of approximately 30,000 hours. Therefore, considerable efforts have been made to develop new phosphors to replace BAM and to improve performance characteristics.

Lanthanum phosphate activated with Tm ³⁺ is a candidate material that has been studied by the applicant of the present invention and is described in the original application of the present invention, ie US patent application Ser. No. 09 / 110,500. The phosphor exhibits two narrow peaks in the UV region (340-370 nm) and visible light peaks at 452 nm. However, the luminance of the phosphor in the visible region does not meet current luminance requirements.

Combinations of UV excited light emitting phosphors and UV light emitting phosphors are known in the art. US Pat. No. 5,747,100 to Peterson teaches a method of making a low voltage phosphor for an electromagnetic radiation display by forming a diffusion barrier of the UV emitting material on the UV excitable phosphor. In lamp applications, UV emitting phosphors are blended with UV excitable phosphors to improve the performance of broad spectrum lamps. For example, US Pat. No. 4,891,550 to Northrop et al. Describes phosphor blends with four different phosphors covering visible light and some UV spectrum (5% to 8%). The purpose of the phosphor blend is to generate UV light in close proximity to sunlight.

US Pat. No. 5,801,483 to Watanabe et al. Discloses a phosphor blend for glimmer lamps that converts ultraviolet light from a fill gas into visible and UV light in the range 320 to 410 nm. The luminescent compound is composed of yttrium oxide activated with trivalent europium emitting red, barium magnesium aluminate emitting blue activated with divalent europium, lanthanum cerium phosphate emitting green activated with trivalent terbium, and divalent lead. A blend of UV-emitting phosphors of activated barium silicate or strontium magnesium pyrophosphate activated with divalent europium, or yttrium phosphate activated with trivalent cerium.

Much of the reported research on lanthanum phosphate based phosphors relates to the application of fluorescent lamps as efficient green phosphors and to their performance. It is documented in detail in many patents on the development of lanthanum phosphate activated with terbium and cerium. Different manufacturing methods and the introduction of various impurities have been attempted to improve the life and performance of lamps.

US Patent No. 3,211,666 to William A. McAllister discloses the use of lanthanum phosphate activated with a variety of rare earth activated vapors for high pressure mercury vapor lamps and CRTs. Specific phosphors were synthesized by mixing 2 moles of ammonium dihydrogen ortho phosphate, 0.08 moles of rare earth oxide, and 1 mole of lanthanum oxide, and burning them at 1100 ° C. for 90 minutes under nitrogen atmosphere.

Y, Gd, La phosphate activated with rare earths (Ce, Tb, Eu, Tm, Yb, Pr, Nd) in US Pat. No. 3,507,807 was synthesized by reacting each solution with a phosphoric acid solution. The dried precipitate was burned in air at 1150 to 1200 ° C. for 3 to 4 hours.

The PCT patent (WO 99/21938) describes the preparation of lanthanum phosphate comprising thulium from each salt and phosphoric acid in the presence of flux at 1000 ° C.

Nakajima et al. US Pat. No. 4,423,349 describes two methods for synthesizing the phosphor. In the first method, the lanthanide carbonate is reacted with phosphoric acid at 75 ° C. and then calcined at 1150 ° C. for 75 minutes. In the second method, the co-precipitated lanthanide oxalate is oxidized to a single phase lanthanide oxide at 800 ° C. Diammonium phosphate is mixed with oxides and burned at 1200 ° C. Boron oxide or ammonium borate is also added before firing to improve the reaction and also improve the brightness.

US Pat. No. 5,091,110 to Albert et al. Discloses a process for preparing lanthanum cerium terbium phosphate phosphors in a two step process. The method comprises forming an aqueous solution of lanthanide nitrate and an aqueous solution of diammonium phosphate, combining the two together, co-precipitating with lanthanum terbium cerium phosphate, and then burning the mixture at a higher temperature to form the phosphor. Boron phosphate is used as a phosphate source because it is stable at elevated temperatures (see US Pat. No. 5,132,042), and lithium carbonate is also used as a flux forming compound to improve the solubility of lanthanide phosphates in boron oxide solutions formed during processing (US patent). 5,154,852).                         

Lanthanum phosphate activated with terbium and cerium is also prepared by reacting a monoammonium phosphate solution with each rare earth nitrate solution (Collin et al. US Pat. No. 5,340,556). The resulting powder is calcined at 900 ° C. in air or in a non-reducing atmosphere to give the phosphor as a 250 nm dense aggregate. XRD analysis revealed that the resulting phosphor powder had a monoclinic structure. Small sized phosphor particles can be prepared by adding excess boric acid and lithium carbonate as flux in the starting mixture followed by combustion (see US Pat. No. 5,651,920 to Chau et al.).

US Pat. No. 5,746,944 to Braconnier et al. Discloses a lanthanum / cerium / terbium mixed green phosphor that precipitates directly by reacting a first solution of soluble lanthanum, cerium and terbium salts with a second solution containing phosphate ions.

HDTVs and similar types of display devices must have high resolution and high brightness to meet expected performance. This can currently only be achieved with thin phosphor screens consisting of very small phosphor particles (0.5 to 2 μm) in the proximity gyrostructure. Screens with small particles have higher packing densities and also require less binder content. It is known that lanthanum phosphate activated with terbium and cerium has high quantum efficiency, better stability at working temperatures and longer lifetime, especially under 254 nm UV excitation (small glimmer lamp). However, only very limited information is available for fabrication and luminescence studies for thulium activated lanthanum phosphate phosphors.

Stable phosphor complexes or blends have an active Tm ³⁺ , Li ⁺ and any selective amount of auxiliary activator alkaline earth element (Ba, Sr, Ca or Mg) (AE ²⁺ ) and empirical formula (La _1-xyz Tm) lanthanum phosphate phosphor represented by _x Li _y AE _z ) PO ₄ (wherein 0.001 ≦ x ≦ 0.05, 0.01 ≦ _y ≦ 0.05, and 0 ≦ _z ≦ 0.05), and 15 to 30% by weight of (i) empirical formula (Ba Barium magnesium alumina activated with divalent europium represented _{by 1-x} Eu _x ) OMg _y O (Al ₂ O ₃ ) _z (wherein 0.005 ≦ _x ≦ 0.05, ₁ ≦ _y ≦ ₂ , and 5 ≦ _z ≦ 7) Nates (BAM); Or (ii) empirical formula (Ba _1-x Eu _x ) OMg _y O (Al _2-v La _v O ₃ ) _z (wherein 0.005 ≦ _x ≦ 0.05, ₁ ≦ _y ≦ ₂ , 5 ≦ _z ≦ 7 and 0.1 ≦ barium lanthanum magnesium aluminate (BLMA) activated with a divalent europium represented by v ≦ 1; Or (iii) empirical formula (x.Sr, y.Ba, z.Cz, u.Mg) ₅ (PO ₄ ) ₃ Cl (where x + y + z + u = 0.1, 0 ≦ x ≦ 1.0, 0 ≦ alkaline earth chloro apatite activated by divalent europium represented by y ≦ 1.0, 0 ≦ z ≦ 1.0 and 0 ≦ u ≦ 1.0 (AECAP); Or (iv) calcium chloro borate (CCB) activated with divalent europium represented by the empirical formula (Ca _5-x Eu _x ) B ₅ O ₉ Cl (wherein 0.005≤x≤0.05).

Lanthanum Phosphate Phosphor (hereinafter referred to as LPT)

The phosphors disclosed below are synthesized by various methods, namely solid state reactions and sol-gel / xerogel methods according to the required particle distribution. The sol-gel / xerogel method is used to produce particles of size (0.05 to 1 μm) up to the micrometer unit and the solid state reaction is used to produce particles of normal size (0.1 to 4 μm).

In synthesizing fine powders and, in particular, phosphor materials, the sol-gel / xerogel methods outperform conventional methods. Since all starting materials are mixed at the molecular level in solution, high uniformity can be achieved. Incorporation of impurities through the solution (activator / co-activator / sensitizer) is easy and effective. The pores of properly dried xerogels are often extremely small and the components of the uniform gel are well mixed. The surface area of the powder produced from the sol-gel is very large, lowering the process temperature.

Impurities other than active and auxiliary activators, which remain in the phosphor material obtained by conventional synthesis, typically degrade the performance and / or life of the phosphors used in display applications. Since the phosphor material is extremely sensitive to impurities even at the ppb level, the sol-gel / xerogel method with the final low reaction temperature minimizes the incorporation of impurities.

As the size of the phosphor particles decreases, the likelihood of electrons and holes (e-h) being trapped in the admixture (s) increases and the e-h localization improves the rate of recombination through the admixture (s). Small particle sizes can further increase titrant concentration levels.

The blue phosphor of the invention uses lanthanum phosphate phosphors incorporating Tm ³⁺ , AE ²⁺ and Li ⁺ produced by sol-gel / xerogels and solid state processes. More specifically, the present invention provides Tm ³⁺ represented by the empirical formula (La _1-xyz Tm _x Li _y AE _z ) PO ₄ , wherein 0.001 ≦ x ≦ 0.05, 0.01 ≦ _y ≦ 0.05, and 0 ≦ _z ≦ 0.05. A method for forming a lanthanum phosphate phosphor in which AE ²⁺ (Ba, Sr, Ca or Mg) and Li ⁺ is incorporated is provided.

The method is

(1) reacting a dilute solution comprising a lanthanum source, a thulium source, a lithium source, an alkaline earth source, and an organic precursor providing a phosphor source in an acid medium to form a sol, a gel and then a xerogel; And

(2) pyrolysing the powder obtained from (1) at a temperature in the range of 900 to 1000 ° C; or

(3) mixing a powder source of lanthanum, thulium, lithium, optionally alkaline earth, and an inorganic precursor providing the phosphor source to form a mixed powder; And,

(4) heating the mixed powder at a solid state reaction temperature (1000 to 1100 ° C.)

It includes.

Life is a very important issue for displays. Blue phosphors are weak components in most displays and lamps because they have a shorter lifespan than other phosphors (green and red). Since commercially available divalent europium activated barium magnesium aluminate-based phosphors do not meet current display life requirements, new phosphors and methods of their synthesis have been developed that overcome the above limitations. Small sized phosphor particles are particularly suitable for use in applications where a high packing density is required.

The present invention encompasses methods of synthesizing LPT phosphors incorporating at least one of ions (Tm ³⁺ ) and trace amounts of Ba, Sr, Ca or Mg, and / or Li ⁺ in an appropriate concentration. The formation (important) of the solid solution mainly depends on the reaction temperature and conditions. In solid state reactions, the individual oxides are reacted at higher temperatures in the presence of excess phosphate. At these temperatures, there is a sufficient possibility that other phases such as individual phosphates and unreacted oxides such as lanthanum, thulium and the like are formed. It is uncertain that the activator ions will be properly incorporated into the lattice of the complex. Finally, the high temperature method will result in the growth of larger particles (> 5 μm).

The sol-gel / xerogel method can be divided into two categories. One is an aqueous-based method starting from a metal salt solution and the other is an alcohol-based method starting from a metal alkoxide. Since metal alkoxides are expensive, lanthanum nitrate and thulium nitrate are selected as metal sources, and trimethyl phosphate is selected as phosphate source.

Initially, trimethyl phosphate and ethanol are mixed at a ratio of 1:10 to prepare a trimethyl phosphate stock solution. In order to better understand these materials many phosphors were prepared under various conditions. The following route was adopted to synthesize a metal precursor.

A lanthanum hydroxide precursor was prepared by adding a base such as ammonium hydroxide to an aqueous solution of LaCl ₃ or La (NO ₃ ) ₃ (0.01M) in water to precipitate the solution. A gelatinous precipitate with a pH of 10.0 to 10.4 was obtained. These gels were washed several times with deionized water to remove counter ions (NO ₃ ⁻ or NH ₄ ⁺ ).

The xerogel product was formed using the following sol-gel method. The required metal solution was prepared by mixing the appropriate amount of each metal nitrate with deionized water of lukewarm to obtain a 0.05-1.0 M solution. A stoichiometric amount of metal (La, Tm, Sr and Li) nitrate or hydroxide solution and trimethyl phosphate were added together so that the ratio of metal to phosphate was always in the range of 0.98 to 1.02. The metal / phosphate solution was transferred to a round bottom flask and peptized at 80-100 ° C., stirrer mantle for 9-18 hours. Boric acid has been attempted in the present invention. Boric acid is suitable because it acts as an acid catalyst as well as flux during the firing process.

After peptization, the sol / gel was left in the container until the sol / gel became a thick gel (5-7 days) followed by a xerogel. These xerogels produced by this method were transferred to a laboratory oven at 60-70 ° C. and left for one day or until dry to form a powder. These powders were transferred to high quality alumina crucibles and heat treatment was performed for 2 cycles. The sample was immersed at 350 ° C. for 2 hours and then heated to 800 to 1000 ° C. for 2 to 12 hours. After cooling to room temperature, a small amount of water was added. Water crushed the hard mass into fine particles. The fine powder was then washed with deionized water and dried at 100 ° C. for 4-6 hours.

Thermal analysis of phosphor samples containing various proportions of metals provides insight into reaction kinetics. The data indicate that the sample had two to three consecutive weight changes in three different temperature ranges. The first change that occurs at about 100 ° C. corresponds to the loss of free water molecules mixed with each metal salt solution. The second weight loss that occurs at about 200 to 300 ° C. is due to the loss of CH ₃ O through oxidation.

X-ray powder diffraction data for a sample burned at 1050 ° C. is shown in FIG. 1. Samples burned below 900 ° C. show some corresponding lines on lanthanum phosphate. All corresponding prominent lines on the lanthanum phosphate are observed in samples burned above 900 ° C. This means that no sample corresponding to metal nitrate or oxide was observed, so the sample was completely converted to each phosphate. This conclusion is also supported by the TGA data. The corresponding line on the metal phosphate is more pronounced as the combustion temperature increases.

Since the phosphor emission depends on morphology, size, crystallinity, defects and grain boundaries, the morphology and PSD of all samples prepared under various conditions have been studied. Scanning electron micrographs of the phosphor samples prepared under various conditions showed that the phosphor particles were uniform and spherical.

The particle size distribution (PSD) of the phosphor prepared from hydroxides and nitrates is shown in FIGS. 2A and 2B. The sample was calcined and washed with water to remove not only the organic residue but also very small particles (<0.5 μm) and left to dry. The emission characteristics of these phosphors were studied on powders at room temperature.

The phosphor samples were exposed to different custom xenon lamps corresponding to 147 and 173 nm (FIGS. 3A, 3B) equipped with MgF ₂ windows and a suitable bandpass filter. The two emission lines at 360 and 451 nm correspond to the ¹ D _2- > ³ H ₆ and ¹ D _2- > ³ H ₄ transitions in the (4f) ¹² electron array of Tm ³⁺ ions. The emission spectra of the Tm ³⁺ incorporated lanthanum nitrate phosphors prepared from metal nitrates are shown in FIGS. 4 and 5. An emission line of about 360 nm is not present in the visible region, but improves the color temperature of the phosphor.

Particularly suitable phosphors are from about 52.3 wt% to about 59.34 wt% lanthanum, from about 0.06 wt% to about 2.97 wt% tulium, 0 wt% to about 0.15 wt% lithium, 0 wt% to about 1.35 wt% alkaline earth One of (Ba, Sr, Ca, Mg), and from about 13.0 wt% to about 15.5 wt% phosphor. All weight percentages are based on the total weight of the phosphor.

The invention will be explained in more detail with reference to the following examples.

Example I

The preparation of thulium incorporated lanthanum phosphate phosphors by the sol-gel / xerogel method using lanthanum, thulium, and hydroxide and acid catalysts of lithium is described in this example. The following starting materials were used. The volume and weight percent per batch for each hydroxide solution (semi-gel) and phosphate solution are listed in Table 1.

chemical substance Volume (cc) Element (Gm) mole% Lanthanum Hydroxide (0.01M) 965 1.342 96.5 Thulium Hydroxide (0.01M) 25 0.042 2.5 Lithium Hydroxide (0.01M) 10 0.0005 1.0 Trimethyl Phosphate (0.1M) 12 0.3235 - Boric Acid (1M) 12 0.13 -

The hydroxide solution was mixed in a round bottom flask. While stirring at 45 ° C., the required amount of trimethyl phosphate solution was slowly added to the hydroxide solution. When the solution reached the desired maximum temperature (90-95 ° C.), a small amount (1-2 cc) of nitric acid or hydrochloric acid was added dropwise together with boric acid, then the solution was peptized at about the same temperature for about 9-12 hours. Using a circulating cooler, the temperature of the water condensation column was maintained at 20 ° C. during peptising. After the flask was cooled to room temperature, the solution (semi-gel) was transferred to a crystallization dish (3 L volume) and left to be exposed to the atmosphere. After a few days (eg 5 to 10 days), the solution was followed by a gel followed by a xerogel.

The clear xerogel was left at 45-50 ° C. for 12 hours in a laboratory oven. Loose chunks from the glass dish were ground with a glass mortar and pestle. The fine powder was collected in a crucible and burned in a box furnace at 300 ° C. for 2 hours (heating rate is 2 degrees per minute) and then burned at 900 ° C. for 6 hours at the same heating rate. The sample was left in the furnace until it cooled to room temperature.

After cooling a hard mass was obtained. A small amount of water made the solid mass into fine particles. This fine phosphor powder was stirred ultrasonically in water. Sonication helped split the cluster into very small particles. After washing with water, the powder was dried at 100 ° C. for 6 hours. The solution containing the phosphor was centrifuged in order to recover particles of size (<0.05 μm) up to the μm unit. Depending on the amount required, it can be scaled up to 10 times or more. Quantitative analysis and plasma emission spectroscopy by CHN analysis of the phosphors are described in Table 2.

element weight% C 0.05 H 0.00 N 0.04 Li ₂ O 0.06 P ₂ O ₅ 30.40 La ₂ O ₃ 67.38 Tm ₂ O ₃ 2.07

Excited by excitation sources (Xe lamps) at 147 and 173 nm, the emission properties of these phosphors were studied, which are described in Table 9 below. The average particle size is also listed in the same table for comparison.

Example II

A process according to the invention of the thulium incorporated lanthanum phosphate phosphor by the sol-gel / xerogel method using lanthanum nitrate, thulium nitrate, lithium nitrate and trimethyl phosphate in the presence of an acid catalyst is described in this example. have. Gram and weight percent units of starting material used in this example are listed in Table 3.

chemical substance Volume (cc) Element (Gm) mole% Lanthanum Nitrate (0.02M) 96.5 2.683 96.5 Thulium Nitrate (0.02M) 25 0.084 2.5 Lithium Nitrate (0.02M) 10 0.001 1.0 Trimethyl Phosphate (0.1M) 25 0.674 - Boric Acid (1M) 25 0.27 -

The nitrate solution was mixed in a round bottom flask. While stirring at 45 ° C., the required amount of methyl phosphate solution was slowly added to the nitrate solution. This solution was peptized at 90 ° C. for about 12 hours. The remaining manufacturing processes (burning, cooling, grinding, washing and drying) were the same as those mentioned in Example I. The results of CHN analysis of the phosphors are shown in Table 4 below.

element weight% C 0.07 H 0.02 N 0.06

The emission characteristics of the phosphors studied by excitation with 147 nm and 173 nm excitation sources (Xe lamps), respectively, are shown in Table 9. For comparison, the average particle size of each sample is listed in the same table.

Example III

In this example, a thulium-incorporated lanthanum phosphate phosphor is prepared by using a sol-gel / xerogel method according to the present invention using lanthanum nitrate, thulium nitrate, lithium nitrate, strontium nitrate and trimethyl phosphate in the presence of an acid catalyst. The method is described. G and weight percent per batch of starting material used in this example are listed in Table 5 below.

chemical substance Volume (CC) Element (Gm) mole% Lanthanum Nitrate (0.02M) 955 2.655 95.5 Thulium Nitrate (0.02M) 25 0.084 2.5 Lithium Nitrate (0.02M) 10 0.001 1.0 Strontium Nitrate (0.02M) 10 0.013 1.0 Trimethyl Phosphate (0.1M) 25 0.674 - Boric acid (1M) 25 0.27 -

The nitrate solution was mixed in a round bottom flask. While stirring at 45 ° C., the required amount of methyl phosphate solution was slowly added to the nitrate solution. This solution was peptized at 90 ° C. for about 12 hours. The remaining manufacturing processes (burning, cooling, grinding, washing and drying) were the same as those mentioned in Example I. The results of CHN analysis of the phosphors are shown in Table 6 below.

element weight% C 0.04 H 0.00 N 0.07

The emission characteristics of the phosphors studied by excitation with 147 nm and 173 nm excitation sources (Xe lamps), respectively, are listed in Table 9. For comparison, the average particle size of each sample is listed in the same table.

Example IV

This example describes the preparation of a thulium-incorporated LPT phosphor using lanthanum nitrate, thulium nitrate, lithium nitrate, ammonium dihydrogen phosphate and boric acid by a solid state reaction according to the present invention. G and weight percent per batch of starting material used in this example are listed in Table 7 below.

chemical substance Volume (Gm) Element (Gm) mole% Lanthanum Nitrate 8.36 2.683 96.5 Thulium Nitrate 0.18 0.084 2.5 Lithium nitrate 0.14 0.001 1.0 Ammonium Dihydrogen Phosphate 3.2 0.8585 - Boric acid 1.0 0.063 -

The nitrate, ammonium dihydrogen phosphate and boric acid powder were mixed and ground in an alumina mortar using a pestle. The resulting mixture was burned at a high temperature of 1000-1100 ° C. The remaining manufacturing process (cooling, grinding, washing and drying) was the same as the method mentioned in Example I. The results of CHN analysis of the phosphors are shown in Table 8 below.

element weight% C 2.92 H 0.09 N 0.15

The emission characteristics of the phosphors studied by excitation with 147 nm and 173 nm excitation sources (Xe lamps), respectively, are listed in Table 9. For comparison, average particle sizes are listed in the same table.

Phosphor Relative strength @ here Color adjustment Particle size (μm) 147 nm 173 nm x y Example I 97 98 0.1442 0.0371 0.05-1.0 Example II 100 100 0.1441 0.0371 0.05-2.0 Example III 98 98 0.1444 0.0369 0.05-2.0 Example IV 94 97 0.1440 0.0370 0.05-3.0

As the data in Table 9 demonstrates, the phosphors of Examples I to IV prepared by the sol-gel / xerogels of the present invention and the solid state reaction method provide a range of particle sizes, but generally high It offers a level of color saturation, brightness, short duration and long life.

Phosphor complex / blend (LPT, BAM, BLMA, AECP or CCB)

In the following, barium lanthanum magnesium aluminate (BLMA), alkaline earth activated with an appropriate concentration of activator ion (Tm ³⁺ ) and LPT incorporating trace amounts of AE ²⁺ and / or Li ⁺ , and a small amount of divalent europium Phosphor complexes or blends containing halo phosphate (AECP) or calcium chloro borate (CCB) are described above.

Phosphors activated / incorporated with Tm ³⁺ , in particular lanthanum phosphate, are excited by VUV and then emit two narrow bands of emission peaks at 360 and 451 nm ( ¹ D ₂ → ³ H ₆ (UV), ¹ D ₂ → ³ H). ₄ (corresponds to visible light)). For display applications, the UV portion of the spectrum is not available.

Without considering the UV part of the spectrum, the phosphor efficiency is very low. If the UV portion of the emission spectrum is used, ie by finding phosphors that can be excited by UV as well as VUV, the phosphor system can be more efficient. It is contemplated that by mixing Tm ³⁺ activated phosphors with a small amount of other phosphors, for example Eu ²⁺ activated BLMA or AECP, the overall efficiency of the phosphor can be substantially improved. In the luminescence process, the UV photons emitted by the Tm ³⁺ center are absorbed by the second phosphor along with the VUV photons from the Xe plasma and then emit visible light near 452 nm.

Phosphor complexes have been prepared by coating a thin layer of BAM or BLMA or AECP on LPT phosphor particles. For example, AECP gels are prepared by the following method.

First, trimethyl phosphate stock solution was prepared by mixing trimethyl phosphate and ethanol in a ratio of 1:10. To better understand these materials, many phosphors were produced under different conditions. Metal precursors were synthesized by mixing the appropriate amount of each metal chloride in lukewarm deionized water to obtain a 0.05-0.5 M solution. A stoichiometric amount of alkaline earth metal and europium chloride or europium hydroxide solution and trimethyl phosphate were added. The metal / phosphate solution was transferred to a round bottom flask and peptized at 80-100 ° C. for 10-20 hours in a stirrer mantle. In addition to acid catalysts, small amounts of hydrochloric acid acting as halogen donors were used.

After peptizing, the required amount of xerogel was mixed with LmT powder activated with Tm ³⁺ (particle size ranging from 1.0 to 2.0 μm) and spun in open containers for several days or until they became powder. This powder was transferred to a high grade alumina boat and heat treatment was performed for two cycles. Samples were immersed at 350 ° C. for 2-4 hours and then heated in air at 900-1000 ° C. for 2-12 hours. After pulverizing the powder, the mass was reheated for 2-4 hours at 1000 ° C. in a forming gas (4.5% H ₂ and the remainder N ₂ ). After cooling to room temperature, the fine powder was washed with deionized water and dried at 100 ° C. for 4-6 hours.

Optimization of the required BAM or BLMA or AECP or CCB was achieved by blending the lanthanum phosphate activated with Tm ³⁺ with BAM or BLMA or AECP or CCB activated with varying amounts of Eu ²⁺ within a range of 15 to 30% by weight. . Spectral data for all such blends are activated with 18 to 25% by weight of Eu ²⁺ to absorb all UV energy emitted by the lanthanum phosphate (Tm ³⁺ ) phosphor and convert the energy into visible emission in the blue region. Showed that the phosphor was sufficient.

Phosphor samples were exposed to different custom xenon lamps, optimized for 147 or 173 nm and equipped with MgF ₂ windows and a suitable bandpass filter. The emission spectra of the phosphor blend comprising 25% BAM or BLMA or AECP or CCB and 75% Tm ³⁺ activated lanthanum phosphate are shown in FIGS. 6 and 7 below. AECAP including BLMA and SCAP (Sr ₅ (PO ₃ ) ₃ Cl) such as BAM (BaMgAl ₁₀ O ₁₇ ), BAM2 (BaMg ₂ Al ₁₆ O ₂₇ ), LBAM (BaMgLaA ₁₉ O ₁₇ ), and BSCMCAP ((Sr The emission spectra of, Ca, Ba, Mg) ₅ (PO ₄ ) ₃ Cl)) and CCB (Ca ₅ B ₅ O ₉ Cl) are shown. All weight percentages are based on the total weight of the phosphor. The spectral response of the grating and photomultiplier tube (PMT) in the UV region (300-400 nm) is about 65% compared to the response in the visible region (400-700 nm).

6 and 7 show that the LPT phosphor activated with Tm ³⁺ when excited with an Xe-light source (147 nm or 172 nm) has three narrow at 348 nm (UV), 363 nm (UV) and 451 nm (visible light). The peak is emitted. When LPT was blended with phosphors activated with any of the Eu ²⁺ described above, the intensity of the UV peak was reduced while the intensity of the visible light peak was improved. UV energy emitted by the LPT phosphor was absorbed by the phosphor activated with Eu ²⁺ and emitted in the visible region (about 450 nm).

Example V

For this example, strontium chloro apatite (SCAP) activated with Eu ²⁺ was selected as one of alkaline earth chloro apatite (AECAP). The coating of a thin layer of strontium chloro apatite activated with Eu ²⁺ on an LPT phosphor activated with Tm ³⁺ is described in this example. 14.55 g of strontium chloride and 0.6 g of europium chloride were dissolved in 5 L of hot water (95 DEG C). The solution was acidified by addition of 10 cc of 0.5 M hydrochloric acid. 150 cc of trimethyl phosphate solution (from the stock solution) was added to the metal chloride solution and the mixture was refluxed at 100 ° C. for 24 hours. The solution was left for several days at room temperature or until semigel (500 cc).

43.1 g of LPT (Tm ³⁺ ) phosphor (particle size in the range of 1.0 to 2.0 μm) is added to the semigel and the roller is slowly moved for several days in an open jar or until it becomes a powder (phosphor particles coated with xerogel). Rotated. The powder was transferred to a higher alumina boat and heat treatment was performed for two cycles. In the first heat treatment cycle, the sample was immersed at 350 ° C. for 2-4 hours and then heated in air at 900-1000 ° C. for 2-12 hours. After pulverizing the powder, the mass was reheated in a forming gas (4.5% H ₂ and the remainder N ₂ ) at 1000 ° C. for 2-4 hours. After cooling to room temperature, the fine powder was washed with deionized water and dried at 100 ° C. for 4-6 hours. After washing, the spectrum and lifetime of the resulting powder were measured.

Example VI

For this example, barium magnesium aluminate (BAM) activated with Eu ²⁺ was selected. Coating of a thin layer of Eu ²⁺ activated BAM onto a Tm ³⁺ activated LPT phosphor is described in this example. 20.4 g of aluminum isopropoxide was dissolved in 5 L of hot water (95 ° C.). The solution was acidified by addition of 5 cc of 0.5 M nitric acid. After adding 2.17 g of barium nitrate, 1.4 g of magnesium nitrate, and 0.04 g of europium nitrate, the mixture was refluxed at 110 ° C. for 24 hours. The solution was left for several days at room temperature or until semigel (500 cc). The remaining process of adding, rotating, drying, heating, cooling and washing LPB is the same as described in Example V.

Example VII

It is described in this example to coat a thin layer of barium lanthanum magnesium aluminate (BLMA) activated with Eu ²⁺ on an LPT phosphor activated with Tm ³⁺ . 10.2 g of aluminum isopropoxide was dissolved in 5 L of hot water (95 ° C.). The solution was acidified by addition of 5 cc of 0.5 M nitric acid. After adding 21.65 g of lanthanum nitrate, 21.7 g of barium nitrate, 1.4 g of magnesium nitrate, and 0.04 g of europium nitrate, the mixture was refluxed at 110 ° C. for 24 hours. The solution was left for several days at room temperature or until semigel. The remaining process of adding, rotating, drying, heating, cooling and washing LPB is the same as described in Example V.

Example VIII

Blending LPT phosphors activated with Tm ³⁺ with phosphors emitting blue activated with Eu ²⁺ such as BAM, BLMA, AECP or CCP is described in this example. 25 g of BLMA with particles in the range of 1-2 μm were thoroughly mixed with 75 g of LPT activated with Tm ³⁺ of the same particle size. The resulting blend was burned at 350 ° C. for 60 minutes and used to measure spectra and lifetime.

Phosphor Excitation WL (nm) Relative Intensity (AU) @ 347 nm @ 452 nm Color coordinates x y NTSC - - - 0.1400 0.0800 [LPO ₄ ] _1.0 147 3615 1410 0.1430 0.0407 [LPO ₄ ] _0.75 + [BAM] _0.25 147 931 3600 0.1458 0.0462 [LPO ₄ ] _1.0 173 3077 1176 0.1461 0.0304 [LPO ₄ ] _0.75 + [BAM] _0.25 173 308 2700 0.1462 0.0421

The data in Table 10 provides the intensity and color coordinates of lanthanum phosphate based phosphors activated with Tm ³⁺ with or without BAM.

The phosphor complex / blend of the invention peaks at 452 nm when excited by 147 or 173 nm radiation from the xenon gas mixture and has a narrow band emission in the blue region. The phosphor blend obtained by the present method exhibits uniform, spherical particles in the range of 1 to 2 μm, which is suitable for thin phosphor screens required for various flat panel displays and lamp applications. Phosphor complexes / blends also exhibit better stability (lifetime) than currently available phosphors for plasma display panels when excited by 147 or 173 nm radiation.

It is to be understood that the above description is only illustrative of the invention. Various alternatives and modifications may be devised by those skilled in the art without departing from the invention. Accordingly, the invention is intended to embrace all such alternatives, modifications and variations that fall within the scope of the appended claims.

Improved blue emitting phosphor complexes or blends according to the invention, more specifically can be excited by both a first phosphor which is excited from a vacuum UV (VUV) light source and then emits both ultraviolet (UV) and visible light and both VUV and UV. A complexed phosphor mixture was obtained comprising a second phosphor present.

Claims (17)

^Activator Tm ³⁺ , Li ⁺ and any optional amount of auxiliary activator alkaline earth element (AE ²⁺ ) and empirical formula (La _1-xyz Tm _x Li _y AE _z ) PO ₄ (wherein 0.001 ≦ x ≦ Lanthanum phosphate phosphors represented by 0.05, 0.01 ≦ y ≦ 0.05, and 0 ≦ z ≦ 0.05, and 15 to 30% by weight of the empirical formula (Ba _1-x Eu _x ) OMg _y O (Al ₂ O ₃ ) _z (wherein And 0.005 ≦ x ≦ 0.05, 1 ≦ y ≦ 2, and 5 ≦ z ≦ 7. A phosphor comprising barium magnesium aluminate (BAM). The phosphor of claim 1, wherein the BAM is present in a percentage range of 18% to 25%. ^Activator Tm ³⁺ , Li ⁺ and any optional amount of auxiliary activator alkaline earth element (AE ²⁺ ) and empirical formula (La _1-xyz Tm _x Li _y AE _z ) PO ₄ (wherein 0.001 ≦ x ≦ Lanthanum phosphate phosphor represented by 0.05, 0.01 ≦ y ≦ 0.05, and 0 ≦ z ≦ 0.05, and 15 to 30% by weight of empirical formula (Ba _1-x Eu _x ) OMg _y O (Al _2-v La _v O ₃ ) a phosphor comprising barium lanthanum magnesium aluminate (BLMA) represented by _z (wherein 0.005 ≦ x ≦ 0.05, 1 ≦ y ≦ 2, 5 ≦ _z ≦ 7 and 0.1 ≦ v ≦ 1). The phosphor of claim 3, wherein the BLMA is present in a percentage range of 18% to 25%. ^Activator Tm ³⁺ , Li ⁺ and any optional amount of auxiliary activator alkaline earth element (AE ²⁺ ) and empirical formula (La _1-xyz Tm _x Li _y AE _z ) PO ₄ (wherein 0.001 ≦ x ≦ Lanthanum phosphate phosphors represented by 0.05, 0.01 ≦ y ≦ 0.05, and 0 ≦ z ≦ 0.05, and 15 to 30% by weight of Experimental AE ₅ (PO ₄ ) ₃ Cl (where AE is Sr, Ca, Ba, Mg Phosphorus containing alkaline earth chloro apatite (AECAP) activated with a divalent europium. The phosphor of claim 5, wherein the AECAP is present in a percentage range of 18% to 25%. ^Activator Tm ³⁺ , Li ⁺ and any optional amount of auxiliary activator alkaline earth element (AE ²⁺ ) and empirical formula (La _1-xyz Tm _x Li _y AE _z ) PO ₄ (wherein 0.001 ≦ x ≦ Lanthanum phosphate phosphor represented by 0.05, 0.01 ≦ y ≦ 0.05, and 0 ≦ z ≦ 0.05, and 15 to 30% by weight of the empirical formula (Ca _5-x Eu _x ) B ₅ O ₉ Cl (wherein 0.005 ≦ _x ≦ Phosphor comprising calcium chloro borate (CCB) activated with divalent europium. 8. The phosphor of claim 7, wherein the CCB is present in a percentage range of 18% to 25%. a) activator Tm ³⁺ , Li ⁺ and any selective amount of auxiliary activator alkaline earth element (AE ²⁺ ) and empirical formula (La _1-xyz Tm _x Li _y AE _z ) PO ₄ (where 0.001 ≦ Aluminum isopropoxide, europium nitrate, nitric acid in the presence of nitric acid on a phosphor comprising lanthanum phosphate represented by x ≦ 0.05, 0.01 ≦ y ≦ 0.05, and 0 ≦ z ≦ 0.05 (hereinafter referred to as LPT phosphor). Coating a thin layer of gel obtained by refluxing barium, b) drying the LPT phosphor coated in step a), and c) pyrolysing the coated LPT phosphor in the forming gas to form an LPT / BAM phosphor complex Tm ³⁺ , Li ⁺ and an optional active element of alkaline earth element (AE ²⁺ ), which includes the formula (La _1-xyz Tm _x Li _y AE _z ) PO ₄ (wherein Lanthanum phosphate phosphor represented by 0.001 ≦ x ≦ 0.05, 0.01 ≦ y ≦ 0.05, and 0 ≦ z ≦ 0.05), and 15 to 30% by weight of the empirical formula (Ba _1-x Eu _x ) OMg _y O (Al ₂ O ₃ ) A process for producing a phosphor complex comprising barium magnesium aluminate (BAM) activated with a divalent europium represented by _z (wherein 0.005 ≦ x ≦ 0.05, 1 ≦ y ≦ 2, and 5 ≦ _z ≦ 7). The method of claim 9, wherein the coated LPT phosphor in step b) is heated in air at about 350 ° C. for 2-4 hours and then at 900 ° C.-1000 ° C. for 2-12 hours. The method of claim 9, wherein the LPT phosphor coated in step c) is heated in a forming gas at about 1000 ° C. for 2 to 4 hours. a) activator Tm ³⁺ , Li ⁺ and any selective amount of auxiliary activator alkaline earth element (AE ²⁺ ) and empirical formula (La _1-xyz Tm _x Li _y AE _z ) PO ₄ (where 0.001 ≦ trimethyl phosphate, europium chloride, and barium chloride, in the presence of hydrochloric acid, on a phosphor comprising lanthanum phosphate represented by x ≦ 0.05, 0.01 ≦ y ≦ 0.05, and 0 ≦ z ≦ 0.05 (hereinafter referred to as LPT phosphor); Coating a thin layer of gel obtained by refluxing one or more of magnesium chloride, strontium chloride and calcium chloride, b) drying the LPT phosphor coated in step a), and c) pyrolysing the coated LPT phosphor in the forming gas to form chloro apatite phosphor complex activated with Eu ²⁺ Tm ³⁺ , Li ⁺ and an optional selective amount of auxiliary activator alkaline earth element (AE ²⁺ ), comprising the formula (La _1-xyz Tm _x Li _y AE _z ) PO ₄ (wherein Lanthanum phosphate phosphor represented by 0.001 ≦ x ≦ 0.05, 0.01 ≦ y ≦ 0.05, and 0 ≦ z ≦ 0.05), and 15 to 30% by weight of the experimental formula AE ₅ (PO ₄ ) ₃ Cl (where AE is Sr, Ca , Ba, Mg) containing a divalent europium activated alkaline earth chloro apatite (AECAP). The method of claim 12, wherein the coated LPT phosphor in step b) is heated in air at about 350 ° C. for 2-4 hours and then at 900 ° C.-1000 ° C. for 2-12 hours. The method of claim 12, wherein the LPT phosphor coated in step c) is heated in a forming gas at about 1000 ° C. for 2 to 4 hours. a) activator Tm ³⁺ , Li ⁺ and any selective amount of auxiliary activator alkaline earth element (AE ²⁺ ) and empirical formula (La _1-xyz Tm _x Li _y AE _z ) PO ₄ (where 0.001 ≦ Aluminum isopropoxide, europium nitrate, nitric acid in the presence of nitric acid on a phosphor comprising lanthanum phosphate represented by x ≦ 0.05, 0.01 ≦ y ≦ 0.05, and 0 ≦ z ≦ 0.05 (hereinafter referred to as LPT phosphor). Coating a thin layer of gel obtained by refluxing lanthanum and barium nitrate, b) drying the LPT phosphor coated in step a), and c) pyrolysing the coated LPT phosphor in the forming gas to form an LPT / BLMA phosphor complex Tm ³⁺ , Li ⁺ and an optional active element of alkaline earth element (AE ²⁺ ), which includes the formula (La _1-xyz Tm _x Li _y AE _z ) PO ₄ (wherein Lanthanum phosphate phosphor represented by 0.001 ≦ x ≦ 0.05, 0.01 ≦ y ≦ 0.05, and 0 ≦ z ≦ 0.05), and 15 to 30% by weight of the empirical formula (Ba _1-x Eu _x ) OMg _y O (Al _2-v Activated barium lanthanum magnesium aluminate (BLAM) represented by La _v O ₃ ) _z (wherein 0.005 ≦ x ≦ 0.05, 1 ≦ y ≦ 2, and 5 ≦ _z ≦ 7 and 0.1 ≦ _v ≦ 1) Method for producing a phosphor complex comprising a). The method of claim 15, wherein the coated LPT phosphor in step b) is heated in air at about 350 ° C. for 2-4 hours and then at 900 ° C.-1000 ° C. for 2-12 hours. The method of claim 15, wherein the LPT phosphor coated in step c) is heated in a forming gas at about 1000 ° C. for 2-4 hours.

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