KR20080026328A - Phosphor and method for preparing the same - Google Patents

Abstract

A phosphor based on an oxysulfide compound is provided to realize excellent luminance and color purity suitable to be used in various electronic devices including CRTs, VFDs or FEDs. A phosphor is represented by the formula of (Y2-xGdx)O2S:Qy, wherein 0.05<x<1.95; Q is at least one element selected from the group consisting of Ce, Pr, Sm, Eu, Tb and Tm; and y is 0.01-0.2 moles per mole of Y+Gd. The phosphor is obtained by the method comprising the steps of: mixing at least one of Y-containing compounds, Gd-containing compounds, Ce-containing compounds, Pr-containing compounds, Eu-containing compounds, Tb-containing compounds and Tm-containing compounds, sulfur(S) and a solvent; and sintering the resultant mixture.

Description

Phosphor and method for preparing the same

1 is a schematic cross-sectional view of an embodiment of an electron emitting device according to the invention,

2 is a graph showing the CL characteristics of one embodiment of the phosphor according to the present invention,

3 is a graph showing the color purity of a conventional phosphor and an embodiment of the phosphor according to the present invention,

4 is a graph showing the luminance of the phosphor according to the present invention.

<Short description of drawing symbols>

110: lower substrate 120: cathode electrode

130: insulator layer 140: gate electrode

160: electron emission source 170: phosphor layer

180: anode electrode 190: upper substrate

The present invention relates to a phosphor and a method for producing the same, and more particularly, to an oxidized sulfide-based red phosphor including Y and Gd and a method for producing the same. The phosphor may include various electronic devices including a phosphor layer, for example, a cathode ray tube (hereinafter referred to as a CRT), a vacuum florescent device (hereinafter referred to as a VFD), or an electron emission device (field emission device). , Hereinafter referred to as FED).

VFD, like CRT, is a self-luminous device using phosphors, and is widely used for numeric display of home appliances and automotive substrates. It has been mainly used for small products with small display capacity such as numbers, letters, and symbols, but now it is possible to display high density graphic, and soon it is time to commercialize fluorescent display tubes with full color and representative capacity.

FED is attracting attention as a device having both the advantages of flat panel displays such as LCD and CRT, and is a next generation device that is currently being actively researched and developed. It is based on the principle that electrons are emitted from electron emitters including micro tip electron emitters or carbon nanotubes, and solves the disadvantages of CRTs, which greatly increase the volume and weight depending on the size. It is known to have a performance that can solve the problem of the LCD. FED also has the advantages of thinness, low power consumption, low process cost, excellent temperature characteristics, high speed operation, and is widely used in small color televisions, industrial products and computers. Laptops, monitors, and televisions.

Various red phosphors are used in the phosphor layer provided in the electronic device as described above. For example, Korean Patent Publication No. 1995-004-0192 discloses a pigment-attached red phosphor.

However, a satisfactory luminance and color purity could not be obtained with the conventional red phosphors, and thus improvement thereof is required.

In order to solve the above technical problem, an object of the present invention is to provide an oxide sulfide-based phosphor containing Y and Gd and a method for producing the same.

In order to achieve the above object of the present invention, the first aspect of the present invention provides a phosphor having the formula (1):

<Formula 1>

(Y _{2 - x} Gd _x ) O ₂ S: Q _y

In Formula 1, 0.05 <x <1.95, Q is at least one element selected from the group consisting of Ce, Pr, Sm, Eu, Tb, and Tm, and y is 0.01 mol to 0.2 mol per mol of Y + Gd.

In order to achieve another object of the present invention, the second aspect of the present invention, the Y-containing compound; Gd-containing compounds; Ce-containing compounds One or more compounds selected from the group consisting of Pr-containing compounds, Eu-containing compounds, Tb-containing compounds and Tm-containing compounds; Sulfur (S); And a second step of mixing the flux and a second step of sintering the mixture obtained from the first step.

The phosphor according to the present invention exhibits excellent luminance and color purity, and thus can be usefully used in various electronic devices such as CRT, VFD or FED.

Hereinafter, the present invention will be described in more detail.

The phosphor according to the present invention is an oxysulfide-based phosphor having Y and Gd, more specifically, having the following general formula (1):

<Formula 1>

(Y _{2 - x} Gd _x ) O ₂ S: Q _y

In said Formula (1), 0.05 <x <1.95, Preferably it is 0.14 <x <1.34. Typically, Y contributes to the brightness of the phosphor and Gd can contribute to the brightness and color purity of the phosphor. The range of x is adjusted to realize high brightness and high color purity at the same time. The range of x is related to the molar ratio between Y and Gd. As Y increases, the phosphor may have a cubic structure, and thus the luminance may be improved. Therefore, color purity can be improved. The range of x is a range in which an optimum luminance and color purity can be obtained in consideration of this. In addition, in the range of x, energy levels of Gd may not exist in the maximum charge transfer transition energy section of the yttrium oxysulfide phosphor (Y ₂ O ₂ S system), and thus incident The lost energy can be transferred to an activator (ie, Eu, Tb, etc. denoted Q) without loss, resulting in an increase in luminance.

The phosphor according to the present invention has a matrix containing S in addition to Y and Gd. For example, the light emission mechanism can be divided into host excitation light emission, light emission by charge transfer transition, and light emission by directly emitting an activator, and the maximum charge of Y ₂ O ₃ : Eu. The charge transfer transition energy is 40 cm ^-1 X 10 ³ , whereas in the case of Y ₂ O ₂ S: Eu, the maximum charge transport transition energy is 300 cm ^-1 X 10 ³ , which enables light emission with little energy. Therefore, the inclusion of S in the matrix is advantageous in terms of energy consumption for the same energy, which can lead to an increase in luminance. In addition, when S is substituted for O of the mother, the main emission peak may shift from 612 nm to 618 nm, thereby improving color purity.

Q acts as an activator. An activator is an element that can play a role in actually emitting light. But not to become specific to a particular light-emitting mechanism, the general formula (1) _{of, (Y 2 - x Gd x} ) O 2 with Q or ions of Q substitution in the basic matrix (host) indicated by S has transitions between its base level and excitation level By absorbing or emitting energy by the light emission can be made.

Wherein Q is In particular, the one or more elements selected from the group consisting of Ce, Pr, Eu, Tb, Sm and Tm. As the Q, for example, Eu or Tb can be used alone. Various modifications are possible, such as Eu and Tb can be used together. The content of Q in the phosphor may be expressed based on the sum of the contents of Y and Gd in the phosphor, and the content of Q is 0.01 to 0.2 mol, preferably 0.01 to 0.2 mol, per mol of Y + Gd. At this time, "Y + Gd" means the sum of the number of moles of Y and the number of moles of Gd.

According to one embodiment of the phosphor according to the invention, Q may be Eu. At this time, y may be 0.01 to 0.2 mol, preferably 0.01 to 0.1 mol per mol of Y + Gd.

According to another embodiment of the phosphor according to the invention, Q can be Eu and Tb. At this time, the molar ratio of Eu: Tb may be 1: 0.00001 to 1: 0.1, preferably 1: 0.001 to 1: 0.07. When the content of Tb is less than 0.00001 mole per 1 mole of Eu, the brightness increase effect by Tb cannot be expected, and when the content of Tb exceeds 0.1 mole per mole of Eu, the emission peak of Tb is observed to reduce the color purity. Because it can.

The phosphor according to the present invention as described above is a red phosphor having excellent brightness and color purity.

A method for producing a phosphor according to the present invention includes a Y-containing compound and a co-precipitating salt of a Y-containing compound and a Gd-containing compound; Gd-containing compounds; One or more compounds selected from the group consisting of Ce-containing compounds, Pr-containing compounds, Eu-containing compounds, Tb-containing compounds and Tm-containing compounds are used. More specifically, the method for producing a phosphor according to the present invention includes a Y-containing compound; Gd-containing compounds; At least one compound selected from the group consisting of Ce-containing compounds, Pr-containing compounds, Eu-containing compounds, Tb-containing compounds and Tm-containing compounds; It may include a first step of mixing sulfur (S) and flux and a second step of sintering the mixture obtained from the step.

The Y-containing compound may be selected from Y ₂ O ₃ , Y ₂ (CO ₃ ) ₃ , Y (OH) ₃ , and Y (NO ₃ ) ₃ , but is not limited thereto. Among these, Y ₂ O ₃ is preferable.

The Gd-containing compound may be selected from Gd ₂ O ₃ , Gd ₂ (CO ₃ ) ₃ , Gd (OH) ₃ , and Gd (NO ₃ ) ₃ , but is not limited thereto. Among these, Gd ₂ O ₃ is preferable.

The at least one compound selected from the group consisting of Ce-containing compounds, Pr-containing compounds, Eu-containing compounds, Tb-containing compounds and Tm-containing compounds may be oxides, carbonates, hydroxides of Ce, Pr, Eu, Tb and Tm or And nitrates. Of these, oxides are preferred. For example, one or more of Eu ₂ O ₃ and Tb ₄ O ₇ can be used.

The flux may be a carbonate or phosphate of a Group 1 element. For example, Na ₂ CO ₃ , K ₂ CO ₃ , K ₂ HPO _4, etc. may be used as the flux, but is not limited thereto. The carbonate flux is required to convert the oxide into an sulphide-based phosphor, and the phosphate flux may contribute to brightness enhancement.

Then, the mixture obtained from the first step is sintered to obtain a phosphor.

The sintering step may be carried out at a temperature of 850 ℃ to 1450 ℃, preferably 950 ℃ to 1400 ℃. On the other hand, the sintering step may be performed for 1 hour to 4 hours, preferably 2 hours to 3.5 hours, more preferably 3 hours. When the sintering step is performed at 850 ° C. and less than 1 hour, aggregation between the components included in the mixture is not effectively performed to obtain a phosphor having a satisfactory performance, and the sintering step is more than 1400 ° C. and 4 hours. If carried out, the components contained in the mixture may be lost.

The phosphor as described above may be included in a phosphor layer provided in various electronic devices, for example, CRT, VFD or FED. Among the electronic devices, the FED includes a first substrate and a second substrate disposed to face each other, a cathode electrode formed on the first substrate, an electron emission source formed to be electrically connected to the cathode electrode formed on the substrate, and An anode electrode formed on a second substrate and a fluorescent layer which emits light by electrons emitted from the electron emission source and contains a phosphor according to the present invention are provided.

1 is a cross-sectional view of an embodiment of such an electron emitting device. 1 schematically shows an electron emitting device having a triode structure among various electron emitting devices according to the present invention. The electron emission device 200 illustrated in FIG. 1 includes an upper plate 201 and a lower plate 202, and the upper plate is an upper electrode 190 and an anode electrode 180 disposed on the lower surface 190a of the upper substrate. And a phosphor layer 170 disposed on the bottom surface 180a of the anode electrode.

The lower plate 202 has a lower surface substrate 110 disposed in parallel with the upper substrate 190 at predetermined intervals to have an inner space, and a cathode electrode disposed in a stripe shape on the lower substrate 110 ( 120, a gate electrode 140 arranged in a stripe shape to intersect the cathode electrode 120, an insulator layer 130 disposed between the gate electrode 140 and the cathode electrode 120, and the insulator layer ( 130 and an electron emission source hole 169 formed in a portion of the gate electrode 140 and the electron emission source hole 169 and are energized with the cathode electrode 120 and lower than the gate electrode 140. It has an electron emission source 160 disposed at a height.

The upper plate 201 and the lower plate 202 are maintained in a vacuum at a pressure lower than atmospheric pressure, and the spacer 192 supports the pressure between the upper plate and the lower plate generated by the vacuum and partitions the light emitting space 210. It is disposed between the upper plate and the lower plate.

The anode electrode 180 applies a high voltage required for acceleration of electrons emitted from the electron emission source 160 to allow the electrons to collide with the phosphor layer 170 at high speed. The phosphor of the phosphor layer is excited by the electrons and emits visible light while falling from a high energy level to a low energy level. The phosphor layer comprises a phosphor according to the invention.

The gate electrode 140 serves to facilitate the emission of electrons from the electron emission source 160, and the insulator layer 130 partitions the electron emission source hole 169 and the electrons. It serves to insulate the emission source 160 and the gate electrode 140.

The electron-emitting device of the present invention has been described with an electron-emitting device having a triode structure as shown in FIG. 1 as an example, but the present invention includes not only the triode structure, but also an electron emitting device having another structure including a dipole tube. In addition, it is possible to prevent damage to the electron emission element in which the gate electrode is disposed below the cathode electrode, the gate electrode and / or the cathode electrode due to the arc that is assumed to be caused by the discharge phenomenon, and to focus the electrons emitted from the electron emission source. It can also be used for electron emitting devices with grids / meshes to ensure the safety. On the other hand, it is also possible to apply the structure of the electron emitting device as a display device or a backlight unit.

Hereinafter, the present invention will be described in detail with reference to specific examples, but the present invention is not limited thereto.

EXAMPLE

Example  One

0.6 mole of Y ₂ O ₃ , 0.4 mole of Gd ₂ O ₃ , 0.05 mole of Eu ₂ O ₃ , 2.942 mole of S (from Kanto Chemical.), 1.24 mole of Na ₂ CO ₃ and 0.173 mole of K ₂ HPO ₄ was mixed and then placed in an aluminum crucible and sintered for 3 hours at a temperature of 950 ° C. under 5% hydrogen and 95% N ₂ atmosphere. This was washed with deionized water and dried to obtain a phosphor. This is called phosphor 1.

Example  2

A phosphor was obtained in the same manner as in Example 1, except that it was sintered at 1050 ° C instead of 950 ° C. This is called phosphor 2.

Example  3

A phosphor was obtained in the same manner as in Example 1, except that it was sintered at 1150 ° C instead of 950 ° C. This is called phosphor 3.

Example  4

A phosphor was obtained in the same manner as in Example 1, except that it was sintered at 1250 ° C instead of 950 ° C. This is called phosphor 4.

Example  5

A phosphor was obtained in the same manner as in Example 1, except that it was sintered at 1350 ° C instead of 950 ° C. This is called phosphor 5.

Example  6

A phosphor was obtained in the same manner as in Example 1, except that it was sintered at 1450 ° C instead of 950 ° C. This is called phosphor 6.

Example  7

0.6 mole of Y ₂ O ₃ , 0.4 mole of Gd ₂ O ₃ , 0.05 mole of Eu ₂ O ₃ , (2.942) mole of S (from Kanto Chemical.), 0.00005 mole of Tb ₄ O ₇ , 1.24 mole of Na ₂ CO ₃ and 0.173 mole of K ₂ HPO ₄ are mixed and placed in an aluminum crucible, 5% hydrogen and 95% N ₂ Sintering was carried out for 3 hours at a temperature of 1250 ° C under the atmosphere. This was washed with deionized water and dried to obtain a phosphor. This is called phosphor 7.

Example  8

A phosphor was obtained in the same manner as in Example 4, except that K ₂ CO ₃ was used instead of Na ₂ CO ₃ . This is called phosphor 8.

Example  9

A phosphor was obtained in the same manner as in Example 7, except that 0.5 mole of Y ₂ O ₃ , 0.5 mole of Gd ₂ O ₃ , and K ₂ CO ₃ were used instead of Na ₂ CO ₃ . . This is called phosphor 9.

Comparative example  One

A phosphor was obtained in the same manner as in Example 1, except that 1 mole of La ₂ O ₃ was used instead of 0.6 mole of Y ₂ O ₃ and 0.4 mole of Gd ₂ O ₃ . This is called phosphor A (La ₂ O ₂ S: Eu phosphor).

Comparative example  2

A phosphor was obtained in the same manner as in Example 1, except that 1 mole Y ₂ O ₃ was used instead of 0.6 mole Y ₂ O ₃ and 0.4 mole Gd ₂ O ₃ , and S was not used. This is called phosphor B (Y ₂ O ₃ : Eu phosphor).

Comparative example  3

0.6mole of Y ₂ O ₃ and Gd was used 0.4mole ₂ O ₃ instead of 1mole of Gd ₂ O ₃ with the exception of the point is to obtain a phosphor in the same manner as in Example 1. This is called phosphor C (Gd ₂ O ₂ S: Eu phosphor).

Comparative example  4

A phosphor was obtained in the same manner as in Example 1, except that 1 mole of Y ₂ O ₃ was used instead of 0.6 mole of Y ₂ O ₃ and 0.4 mole of Gd ₂ O ₃ . This is called phosphor D (Y ₂ O ₂ S: Eu phosphor).

Evaluation example  One - CL ( cathodluminescent Evaluation of characteristics

CL characteristics of the phosphor 1 obtained in Example 1 were evaluated and shown in FIG. 2. The CL characteristic evaluation was obtained using an electron beam excitation luminescence measurement-Darsa pro device under 5 kV and 0.6 uA / cm ² conditions.

According to Figure 2, the phosphor 1 can be seen that the maximum intensity in the wavelength range of about 630nm.

Evaluation example  2 - Color purity  evaluation

Color purity was evaluated for the phosphors A to D and the phosphor 1 (indicated by (Y, Gd) ₂ O ₂ S: Eu in FIG. 3), and the results are shown in FIG. 3. Color purity evaluation was performed using an electron beam excitation luminescence measurement-Darsa pro apparatus under 5 kV and 0.6 uA / cm ² ) conditions. More specifically, the color coordinates of each phosphor are shown in Table 1 below:

Phosphor Color coordinates Phosphor A (La ₂ O ₂ S: Eu Phosphor) (0.630, 0.362) Phosphor B (Y ₂ O ₃ : Eu Phosphor) (0.641, 0.351) Phosphor C (Gd ₂ O ₂ S: Eu Phosphor) (0.646, 0.344) Phosphor D (Y ₂ O ₂ S: Eu Phosphor) (0.649, 0.341) Phosphor 1 ((Y, Gd) ₂ O ₂ S: Eu Phosphor) (0.659, 0.334)

According to Table 1, it can be seen that the color purity of phosphor 1 is very high compared to the remaining phosphors.

Evaluation example  3-luminance evaluation

The luminance of the phosphors 1 to 6 was evaluated and shown in FIG. 4. Luminance evaluation was evaluated using an electron beam excitation luminescence measurement-Darsa pro apparatus under 5 kV and 0.6 uA / cm ² conditions. According to Figure 4 it can be seen that the phosphor according to the present invention has excellent brightness in a relatively wide sintering temperature range.

The phosphor according to the present invention is an oxysulfide-based phosphor containing Y and Gd, and has excellent luminance and color purity as compared with the conventional phosphor. The phosphor may be usefully used in various electronic devices such as CRT, VFD or FED.

Claims (7)

Phosphor having Formula 1 <Formula 1> (Y _{2 - x} Gd _x ) O ₂ S: Q _y In Formula 1, 0.05 <x <1.95, Q is at least one element selected from the group consisting of Ce, Pr, Sm, Eu, Tb, and Tm, and y is 0.01 mol to 0.2 mol per mol of Y + Gd. The phosphor according to claim 1, wherein Q is at least one element of Eu and Tb. The phosphor of claim 1, wherein when Q is Eu and Tb, the molar ratio of Eu: Tb is 1: 0.00001 to 1: 0.1. Y-containing compounds; Gd-containing compounds; Ce-containing compound One or more compounds selected from the group consisting of Pr-containing compounds, Eu-containing compounds, Tb-containing compounds and Tm-containing compounds; Sulfur (S); And a first step of mixing the flux; And A second step of sintering the mixture obtained from the first step; Method for producing a phosphor represented by the formula (1) comprising: <Formula 1> (Y _{2 - x} Gd _x ) O ₂ S: Q _y In Formula 1, 0.05 <x <1.95, Q is at least one element selected from the group consisting of Ce, Pr, Sm, Eu, Tb, and Tm, and y is 0.01 mol to 0.2 mol per mol of Y + Gd. The method of claim 4, wherein the flux is at least one selected from the group consisting of carbonates and phosphates of group 1 elements. The method of claim 4, wherein the sintering step is performed at a temperature of 850 ° C. to 1450 ° C. 6.  The method of claim 4, wherein the sintering step is performed for 1 to 4 hours.

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