KR20050101151A - Synthesis of the phosphorescent phosphor of strontium barium aluminates - Google Patents

Abstract

It relates to a manufacturing process of synthesizing a phosphor of - (referred to as barium aluminate or less ^{strontium), Eu 2 +, Dy 3} + system: _- The invention Sr ₁ represents the yellow-green and cyan light emitting characteristic _x Ba _x Al ₂ O ₄ Fluorescent substance was synthesized by solid phase reaction by adding SrCO ₃ , BaCO ₃ , Al ₂ O ₃ as starting material, Eu ₂ O ₃ as activator, Dy ₂ O ₃ as study agent, and B ₂ O ₃ as flux. The sintering process for synthesizing the phosphor was heat-treated for 3 hours at a temperature of 1100 ~ 1400 ℃ in a 95% Ar + 5% H ₂ reducing atmosphere. The amount of Ba added was changed in the range of 0.0-1.0 mol. When the amount of Ba was added in the range of 0.0-0.4 mol, the emission wavelength was yellow-green region. When the amount of Ba was exceeded, the emission wavelength region was changed to a region close to cyan. In addition, as the amount of Ba increases, the intensity of light emission increases and the long afterglow property shows the best characteristic when 0.1 mol of Ba is added. As a result of measuring the excitation and luminescence properties of the powder, the excitation spectrum is excited over a wide wavelength region of 250 to 450 nm, and the emission spectrum shows a maximum peak at 480 to 520 nm.

Description

Synthesis of the Phosphorescent Phosphor of Strontium Barium Aluminates

The present invention relates to a method for producing a luminescent phosphor of strontium-barium aluminate (Sr _1-x Ba _x Al ₂ O ₄ : Eu ²⁺ , Dy ³⁺ ) -based exhibiting yellow-green and blue-green light emission characteristics. Among the phosphor materials, the photoluminescent material is a material having a property of absorbing energy by stimulation of light such as an electric light or sunlight, and then reducing it to visible light and emitting light even in a dark place for a long time. These photoluminescent materials were found in the 11th century in China and Japan and in the 16th century in Europe. Phosphorescent materials can be used as fluorescent paints used in highways, railways, aviation, ports and the first half of buildings, and fluorescent powders can be used as fluorescent glazes in various ceramic products by adding them to transparent glazes. And it has various applications such as luminous clockface and luminous clock.

ZnS: Cu has been invented for a long time as a representative photoluminescent phosphor. However, since sulfide-based photoluminescent phosphors contain harmful elements and are not environmentally stable, they have problems in use. On the other hand, SrAl ₂ O ₄ : Eu ^{2 +} , Dy ^{3 +} photoluminescent phosphors are chemically stable, durable, and do not contain radioactive material as excitation source, and their use is gradually expanding as they are recently known as excellent phosphorescent phosphors. It is becoming. However, in the present invention, strontium-barium aluminate (Sr _1-x Ba _x Al ₂ O ₄ : Eu ²⁺ , Dy ³⁺ ) phosphors emitting light of yellow-green to cyan by adding Ba proposed in the present invention and their use No attempt has been made yet.

An object of the present invention is to produce a photoluminescent material having excellent afterglow characteristics as a phosphor capable of emitting light from yellowish green wavelength to cyan wavelength, and is characterized in that SrAl ₂ O ₄ BaCO ₃ was added to the matrix crystal in the range of 0.0 to 1.0 mol, a small amount of Eu ₂ O ₃ was added as an activator, and a small amount of Dy ₂ O ₃ was added as a activator, and B ₂ O ₃ was added as a flux. The phosphorescent phosphor was prepared by heat treatment at a temperature of 1300 to 1400 ° C. in a reducing atmosphere of 95% Ar + 5% H ₂ to reduce Eu (III) to Eu (II) during the firing process. The luminescence properties and long afterglow characteristics of the strontium-barium aluminate phosphors prepared as described above were investigated. When the amount of Ba added was 0.0 to 0.4 mol, the emission wavelength was yellowish green. The emission wavelength region was changed to a region close to cyan. In addition, when Ba was added, the luminescence intensity was higher and the afterglow property was superior to that when Ba was not added. Therefore, when Ba is appropriately added to the SrAl ₂ O ₄ -based phosphor that emits light at the yellow-green wavelength, light emission from the yellow-green wavelength to the blue-green wavelength can be realized and the phosphorescent phosphor having excellent long afterglow property can be manufactured.

Barium aluminate-strontium according to the invention _{(Sr 1 - x Ba x Al} 2 O 4: Eu 2 +, Dy 3 +) and hold the axial light component fluorescent material as a starting material, as a method of manufacturing are shown in Figure 1 99.9 SrCO ₃ , BaCO ₃ and Al ₂ O ₃ powders of higher purity than% are mixed in an appropriate molar ratio, and Eu ₂ O ₃ and Dy ₂ O ₃ are used as an activator and a study agent, respectively. The molar ratio of each raw material is (SrCO ₃ , BaCO ₃ ): Al ₂ O ₃ : Eu ₂ O ₃ : Dy ₂ O ₃ = 0.97: 1.0: 0.005: 0.01. In addition, by mixing the 3 ~ 4wt% B ₂ O ₃ powder as a flux to lower the reaction temperature to promote the grain growth of the parent crystal and improve the luminous efficiency. That is, SrCO _{3 ,} BaCO ₃ , Al ₂ O ₃ , Eu ₂ O ₃ , B ₂ O ₃ , weighed in the proper molar ratio, are mixed first in the mortar, and mixed with ethanol to prevent the scattering of powder and more effective mixing. Wet mixing using a ball mill for 24 hours. And it is dried for 24 hours at 130 ℃ to remove ethanol contained during mixing. Finally, the dried mixed powder is placed in an alumina boat and heat-treated at a reaction temperature of 1100-1500 ° C. for 3 hours in a reducing atmosphere of (95% Ar + 5% H ₂ ). At this time, the temperature increase rate is kept constant at about 5 ~ 10 ℃ / min.

Hereinafter, an embodiment according to the present invention will be described step by step.

(1) Physical Properties of Strontium-Barium Aluminate Phosphors

FIG. 2 shows scanning electron microscope (SEM) images of powders sintered for 3 hours by changing the prepared mixed powders at 100 ° C intervals from 1100 ° C to 1400 ° C in a (95% Ar + 5% H ₂ ) reducing atmosphere. have. As shown in the photo, it can be seen that particle growth occurred during the sintering process. In other words, when the powder was sintered at 1100 ° C., the particle size was about 1 μm, but at sintering temperature of 1200 ° C. or more, the particles were actively agglomerated, and the particles were grown. The coarsening of the crystal grains is considered to be due to the fact that B ₂ O ₃ added as a flux dissolves during the sintering process to facilitate the sliding and rotation of the particles, thereby promoting the diffusion reaction between the particles. At sintering temperature of 1400 ℃, due to severe vitrification of B ₂ O ₃ , the dissolved B ₂ O ₃ completely covered the powders in a pocket.

Figure 3 is a Sr ₁ subjected to heat treatment at _{1400 ℃ - x Ba x Al 2} O 4: the ^{Eu 2 +, Dy 3 + (} x = 0~1.0mol) X-ray diffraction analysis results. Ba 0 ~ 0.3mol is similar to the diffraction peak of SrAl ₂ O ₄ , Ba 0.5 ~ 1.0mol is similar to the diffraction peak of BaAl ₂ O ₄ .

(2) Excitation Characteristics of Strontium-Barium Aluminate Phosphors

4 is SrAl ₂ O ₄ was sintered at 1400 ℃ 3 hours: measured by scanning from after the light emission wavelength as an excitation spectrum obtained for Eu ^{2 +,} Dy ^{3 +} phosphor is fixed to 520 nm 200nm to 500nm. As shown in the figure, excitation occurs over a wide wavelength range from 250 nm to 450 nm, maximum absorption peak at 360 nm, and other excitation peaks at 260 nm, 330 nm, 380 nm, and 420 nm. These Here peaks are considered to be the combination of this peak occurs from deep levels formed by the crystal defects of the activator agent Eu ^{2 +} a 4 f ⁷ → 4 is f ⁶ 5d according to the ¹⁰⁰² peak and study lubricant here Dy ^{3 +} do. Since the wavelength in the range of 250 nm to 450 nm is also included in the sunlight, the SrAl ₂ O ₄ : Eu ^{2 +} and Dy ^{3 +} phosphors can be easily excited by the sunlight and emit light. It can be seen that it is a fluorescent material capable of emitting light even in ultraviolet light having a shorter wavelength than conventional ZnS: Cu-based having a deteriorating property.

(3) Luminescence Characteristics of Strontium-Barium Aluminate Phosphors

FIG. 5 shows the emission spectrum of a powder sample in which 0.1 mole of Ba was substituted for a mother crystal and heat-treated in a reducing atmosphere of 95% Ar + 5% H ₂ for 3 hours at 1100 to 1400 ° C. FIG. As the excitation light source, light of 360 nm generated from the Xe lamp was used. As shown in the figure, the emission spectrum of Sr _{1 - x} Ba _x Al ₂ O ₄ : Eu ^{2 +} , Dy ^{3 +} (x = 0.1mol) phosphor is 400 ~ 600nm with 510nm-520nm as the maximum emission wavelength. It shows a broad emission spectrum of which is a wavelength similar to that of ZnS: Cu, which is widely used as a conventional photoluminescent material. And as the reaction temperature increased, the emission intensity increased. Thus, increase in emission intensity according to the synthesis temperature is increased by being the Eu ^{3 +} ion substitution is easily reduced to Eu ^{2 +} ions at a temperature of the reducing atmosphere is considered to be due to form a stable light emitting center (luminescence center).

FIG. 6 is a light emission spectrum of a powder sample heat-treated at 1400 ° C. for 3 hours by adding Ba to 0 to 1.0 mol. In this case, 0-0.3 mol emits light at 510-520 nm, whereas 0.5-1.0 mol substitutes show emission spectrum at 480-490 nm. In addition, as can be seen in the figure is the light emitting intensity of BaAl ₂ O ₄ phosphor has shown a relatively more highly than SrAl ₂ O ₄ phosphor.

7 is a strontium-barium aluminate _{(Sr 1 - x Ba x Al} 2 O 4: Eu 2 +, Dy 3 + (x = 0~1.0mol)) during the 1400 ℃ 3 sigan phosphor has the most excellent luminous intensity After the powder heat-treated in a reducing atmosphere of 95% Ar + 5% H ₂ by excitation for 5 minutes by Xe lamp emitting white light similar to the sunlight, afterglow characteristics in the dark field state is measured. As shown in the figure, afterglow intensity tended to decrease with time regardless of the amount of Ba added. In addition, the afterglow property changes according to the amount of Ba added, and the long afterglow property is better than the case where Ba is added, and particularly, when Ba is 0.1 mol, it shows the best long afterglow property. On the other hand Chapter afterglow characteristic is that in the case of usual phosphor by the excitation light of the excitation wavelength 360nm electroluminescent at 480 ~ 520nm as the transition to the re-4 f ⁷ state after excitation in a 4 f ⁷ state to the 4 f ⁶ 5 d ¹ state Afterglow takes a long time to be trapped at a trap level higher than 4 f ⁶ 5 d ¹ due to short wavelength excitation light, and the trapped electrons are released from the trap by thermal energy to reach equilibrium. Because it becomes.

As described above, the strontium-barium aluminate phosphor synthesized according to the present invention exhibits a broad emission spectrum of 400 to 600 nm, and the maximum emission peak is shifted from 520 nm yellow-green emission to 480 nm blue-green emission region as the amount of Ba addition increases. It became. The luminescence and long afterglow characteristics were excellent as the sintering temperature was higher, and the maximum luminescence intensity and afterglow intensity were shown at the sintering temperature of 1400 ° C. If the amount of Ba added is less than 0.5 mole, SrAl ₂ O ₄ Similar to the fluorescent material, the light emission characteristics of the yellow-green wavelength region are shown, and when the molar is 0.5 mole or more, the light emission characteristics of the blue-green wavelength are shown. As a result of measuring the afterglow property according to the amount of Ba added, the afterglow property was better than when Ba was added, and the longest afterglow property was excellent when 0.1 mole of Ba was added. The strontium-barium aluminate phosphor prepared according to the present invention is a photoluminescent phosphor that emits light from a yellowish green wavelength to a cyan wavelength and has excellent long afterglow characteristics.

1 is a process chart for producing strontium-barium aluminate phosphors.

FIG. 2 is a scanning electron microscope (SEM) photograph of strontium-barium aluminate phosphors at different reaction temperatures.

(a) is the powder when the reaction temperature is 1100 ℃,

(b) is the powder form when the reaction temperature is 1200 ℃,

(c) is the powder when the reaction temperature is 1300 ℃,

(d) is powder form when reaction temperature is 1400 degreeC.

3 is an XRD pattern of strontium-barium aluminate phosphors having different amounts of Ba added thereto.

4 is an excitation spectrum of a phosphor.

5 is an emission spectrum according to the sintering temperature of the phosphor to which 0.1 mol Ba is added.

6 is an emission spectrum of strontium-barium aluminate phosphors according to different Ba amounts.

7 is attenuation curves of strontium-barium aluminate phosphors according to different Ba amounts.

Claims (3)

SrAl ₂ O ₄ A method of manufacturing a strontium-barium aluminate-based photoluminescent phosphor which emits light at various wavelengths by adding Ba to a matrix crystal in a range of 0.0 to 1.0 mol. The method according to claim 1, wherein a small amount of 0.005 to 0.01 mol of Eu ₂ O ₃ is added as an activator, and a small amount of 0.01 to 0.02 mol of Dy ₂ O ₃ is added as a activator, and 3 to 4 wt% B ₂ O ₃ is used as a flux. Phosphor prepared by addition. 3. The method of claim 1, wherein the powder is heat-treated at 1100 to 1500 ° C. for 3 hours in a 95% Ar + 5% H ₂ reducing atmosphere to realize light emission from an yellowish green color to a cyan green color.