KR20010026297A - New Silicates Phosphors for Lamp - Google Patents

Abstract

PURPOSE: A novel fluorescent substance which has an improved luminous efficiency regarding ultraviolet rays near 370 nanometer by modifying a conventional luminous substance of (Ba2-xSrx)SiO4:Eu+ is provided. CONSTITUTION: The fluorescent substance, which uses europium as an activator, is represented by the following formula (1), (Ba2-x-y-z-α SrxEuyMzNα). In the formula 1, x is 0≤x≤2, y is 0.001≤y≤0.05, z is 0.001≤z≤0.1, α is 0≤α≤0.1, x+y+z+α is 0≤x+y+z+α≤2, δ is -0.05≤δ≤0.05, M is La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, Sc, Al, Ga and In and L is Li, Na and K.

Description

Silicate Phosphors for New Lamps {New Silicates Phosphors for Lamp}

The present invention relates to a phosphor which is suitable for producing a white light emitting diode intended to be used not only for mercury lamps but also for mercury-free lamps and a method for producing the same.

More specifically, the present invention relates to a phosphor represented by the following Chemical Formula 1 using europium as an activator.

<Formula 1>

(Ba _2-xyz-α Sr _x Eu _y M _z N _α ) SiO _{4 + δ}

In the above formula,

x is 0 ≦ x <2, y is 0.001 ≦ y ≦ 0.05, z is 0.001 ≦ z ≦ 0.1, α is 0 ≦ α ≦ 0.1 and x + y + z + α is 0 ≦ x + y + z + α ≦ 2, δ is −0.05 ≦ δ ≦ 0.05, M is La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, Sc , Al, Ga, In, and N is Li, Na, K.

In addition, the present invention comprises a first heat treatment step of weighing and grinding the starting material according to the composition of the formula (1), and put into an alumina crucible and heated;

A second heat treatment step of naturally cooling the first heat-treated sample in an electric furnace and then regrinding and heating the sample in a tubular electric furnace in which hydrogen gas or hydrogen and nitrogen mixed gas flows into a boat; And

It relates to a method for producing a phosphor of the general formula (1) comprising the step of naturally cooling the second heat-treated sample in a tube electric furnace flowing hydrogen gas or hydrogen and nitrogen mixed gas.

Conventionally, silicate-based phosphors (Ba _2-x Sr _x ) SiO ₄ : Eu ²⁺ (Eu concentrations from 0.0005 to 0.05) are known as phosphors for lamps (J. Electrochem. Soc. 115 (11). ), 1181 (1968) and US Pat. No. 3,505,240 (1970.4.7.). This phosphor has been reported to have high luminous efficiency for ultraviolet rays of 253.7 nm and 365 nm used as excitation sources in mercury lamps. And by adjusting the x value, you can realize various colors from green to yellow.

Recently, attempts have been made to emit white light by applying a phosphor to a diode, which can use ultraviolet light near 370 nm from an InGaN-based light emitting diode (LED) as an excitation source, and (Ba _2-x Sr _x ) SiO ₄ : Eu ^{2 +} phosphor can also be used for this purpose (phosphor Research Society Meeting Digest, 264 , 5 (1996); J. Crystal Growth 195, 242 (1998); and J. Crystal Growth 189/190, 778 (1998 )).

An object of the present invention is to modify the existing (Ba _2-x Sr _x ) SiO ₄ : Eu ²⁺ phosphor to obtain a phosphor having improved luminous efficiency with respect to ultraviolet rays emitted from 365 nm and the light emitting diode.

1 is an emission spectrum obtained by exciting a phosphor obtained in Examples 1 and 2 of the present invention and a conventional Ba _0.99 Sr _0.99 Eu _0.02 SiO ₄ phosphor with 365 nm ultraviolet ray.

FIG. 2 is an excitation spectrum of 515 nm emission of phosphors obtained in Examples 1 and 2 of the present invention and conventional Ba _0.99 Sr _0.99 Eu _0.02 SiO ₄ phosphors. FIG.

3 is an excitation spectral distribution diagram for 515 nm emission of phosphors obtained in Examples 3 and 4 of the present invention and conventional Ba _0.99 Sr _0.99 Eu _0.02 SiO ₄ phosphors.

4 is an excitation spectral distribution diagram for 515 nm light emission of a phosphor obtained in Example 5 of the present invention and a conventional Ba _0.99 Sr _0.99 Eu _0.02 SiO ₄ phosphor.

The present inventors found that a part of the alkaline earth metal of the (Ba _2-x Sr _x ) SiO ₄ : Eu ²⁺ phosphor was selected from the rare earth elements La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm. When substituted with Al, Ga, In, etc., which are Group 3 elements, Yb, Lu, Y, Sc, etc., and with alkali metal ions Li, Na, K, etc., the brightness is more than 80% for UV of 365 nm I found that it can be improved.

Accordingly, the present invention relates to a phosphor represented by the following Chemical Formula 1 having europium as an activator.

<Formula 1>

(Ba _2-xyz-α Sr _x Eu _y M _z N _α ) SiO _{4 + δ}

In the above formula,

x is 0 ≦ x <2, y is 0.001 ≦ y ≦ 0.05, z is 0.001 ≦ z ≦ 0.1, α is 0 ≦ α ≦ 0.1 and x + y + z + α is 0 ≦ x + y + z + α ≦ 2, δ is −0.05 ≦ δ ≦ 0.05, M is La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, Sc , Al, Ga, In, and N is Li, Na, K.

In addition, the present invention comprises a first heat treatment step of weighing and grinding the starting material according to the composition of the formula (1), and put into an alumina crucible and heated;

A second heat treatment step of naturally cooling the first heat-treated sample in an electric furnace and then regrinding and heating the sample in a tubular electric furnace in which hydrogen gas or hydrogen and nitrogen mixed gas flows into a boat; And

It relates to a method for producing a phosphor of the general formula (1) comprising the step of naturally cooling the second heat-treated sample in a tube electric furnace flowing hydrogen gas or hydrogen and nitrogen mixed gas.

The Si compound which is a synthetic raw material used to prepare the phosphor of Formula 1 of the present invention is SiO ₂ having a purity of 99% or more, and Ba, Sr, Eu, La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy , Ho, Er, Tm, Yb, Lu, Y, Sc, Al, Ga, In, etc. are in the form of nitrates, carbonates or oxides having a purity of at least 99.9%, specifically BaCO ₃ , SrCO ₃ , Eu ₂ O ₃ , Al ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O ₃ and the like, Li, Na, K and the like is a carbonate form of 99.9% or more purity, specifically Na ₂ CO ₃ and the like.

Starting materials are usually changed for 30 minutes or more in agate mortars. Then, the sample after the first heat treatment is ground again for 10 minutes in agate mortar.

The first heat treatment is performed for 2 hours to 4 hours at 700 ℃ to 1000 ℃. In addition, the second heat treatment is performed for 2 hours to 10 hours at 1000 ℃ ~ 1300 ℃.

Hereinafter, although an Example is given and embodiment of this invention is described more concretely, this invention is not limited by these Examples.

<Example 1>

Preparation of Ba _0.97 Sr _0.97 Eu _0.02 Al _0.02 Na _0.02 SiO ₄ (x = 0.97, y = 0.02, z = 0.02, α = 0.02, δ = 0, M = Al, N = Na)

Starting materials BaCO ₃ 3.8292 g, SrCO ₃ 2.8642 g, Eu ₂ O ₃ 0.0704 g, Al ₂ O ₃ 0.0204 g, Na ₂ CO ₃ 0.0212 g, SiO ₂ 1.2065 g was mixed in a mortar mortar for about 30 minutes. The mixture was transferred to an alumina crucible, heated to 950 ° C. over 2 hours, and reacted at 950 ° C. for 2 hours.

The first heat-treated sample was naturally cooled to room temperature in an electric furnace, and then ground in an agate mortar for 10 minutes. This was put in a platinum boat and placed in a tube electric furnace, and hydrogen was flowed for 3 hours, heated to 1200 ° C. over 2 hours while flowing 10 cc of hydrogen per minute, and heated at 1200 ° C. for 3 hours.

The second heat-treated sample was naturally cooled in an electric furnace while flowing hydrogen to obtain a phosphor.

The brightness of this phosphor was compared with the brightness of Ba _0.99 Sr _0.99 Eu _0.02 SiO ₄ , which was produced by the same method at various excitation wavelengths, showing 160% at 365 nm, 155% at 400 nm and 136% at 450 nm.

The emission spectra of the phosphor of this embodiment and the Ba _0.99 Sr _0.99 Eu _0.02 SiO ₄ phosphor have the same shape, but the excitation spectrum has a slightly different shape. Specifically, FIG. 1 compares the emission spectra of two phosphors obtained by excitation with 365 nm ultraviolet rays, and FIG. 2 compares the excitation spectra of two phosphors with respect to 515 nm showing the maximum emission intensity.

<Example 2>

Preparation of Ba _0.97 Sr _0.97 Eu _0.02 Y _0.02 Na _0.02 SiO ₄ (x = 0.97, y = 0.02, z = 0.02, α = 0.02, δ = 0, M = Y, N = Na)

Same as Example 1, except that 3.8292 g of BaCO _3, 2.8642 g of SrCO _3, 0.0704 g of Eu ₂ O _3, 0.0452 g of Y ₂ O _3, 0.0212 g of Na ₂ CO _{3, and} 1.2065 g of SiO ₂ were used as starting materials. The title phosphor was synthesized by the method.

The brightness of this phosphor was compared with that of Ba _0.99 Sr _0.99 Eu _0.02 SiO ₄ , which was produced by the same method, and showed brightness of 181% at 365 nm, 182% at 400 nm and 175% at 450 nm.

The emission spectra of the phosphor of this embodiment and the Ba _0.99 Sr _0.99 Eu _0.02 SiO ₄ phosphor have the same shape, but the excitation spectrum has a slightly different shape. Specifically, FIG. 1 compares the emission spectroscopy of two phosphors obtained by excitation with 365 nm ultraviolet rays, and FIG. 2 compares the excitation spectroscopy of two phosphors with respect to 515 nm showing the maximum emission intensity.

<Example 3>

Preparation of Ba _0.98 Sr _0.98 Eu _0.02 Gd _0.02 SiO _4.01 (x = 0.98, y = 0.02, z = 0.02, α = 0, δ = 0.01, M = Gd)

The titled phosphor was synthesized in the same manner as in Example 1, except that 3.8686 g of BaCO _3, 2.8937 g of SrCO _3, 0.0704 g of Eu ₂ O _3, 0.0725 g of Gd ₂ O _{3, and} 1.2065 g of SiO ₂ were used as starting materials. It was.

The brightness of this phosphor was compared with that of Ba _0.99 Sr _0.99 Eu _0.02 SiO ₄ , which was produced by the same method, and showed brightness of 126% at 365 nm, 136% at 400 nm and 162% at 450 nm.

The luminescence spectroscopy of the phosphor of this embodiment and the Ba _0.99 Sr _0.99 Eu _0.02 SiO ₄ phosphor have the same shape, but the excitation spectral distribution is different. Specifically, FIG. 3 compares excitation spectral distributions of two phosphors with respect to 515 nm showing maximum emission intensity.

<Example 4>

Preparation of Ba _0.97 Sr _0.97 Eu _0.02 Gd _0.02 Na _0.02 SiO ₄ (x = 0.97, y = 0.02, z = 0.02, α = 0.02, δ = 0, M = Gd, N = Na)

Same as Example 1, except that 3.8292 g of BaCO _3, 2.8642 g of SrCO _3, 0.0704 g of Eu ₂ O _3, 0.0725 g of Gd ₂ O _3, 0.0212 g of Na ₂ CO _{3, and} 1.2065 g of SiO ₂ were used as starting materials. The title phosphor was synthesized by the method.

The brightness of this phosphor was compared with that of Ba _0.99 Sr _0.99 Eu _0.02 SiO ₄ , which was produced by the same method, and showed 147% at 365 nm, 160% at 400 nm and 190% at 450 nm.

The luminescence spectroscopy of the phosphor of this embodiment and the Ba _0.99 Sr _0.99 Eu _0.02 SiO ₄ phosphor have the same shape, but the excitation spectral distribution is different. Specifically, FIG. 3 compares excitation spectral distributions of two phosphors with respect to 515 nm showing maximum emission intensity.

<Example 5>

Preparation of Ba _0.91 Sr _0.91 Eu _0.02 Gd _0.08 Na _0.08 SiO ₄ (x = 0.91, y = 0.02, z = 0.08, α = 0.08, δ = 0, M = Gd, N = Na)

Same as Example 1, except that 3.5923 g BaCO _3, 2.6870 g SrCO _3, 0.0704 g Eu ₂ O _3, 0.2900 g Gd ₂ O _3, 0.0848 g Na ₂ CO _{3, and} 1.2065 g SiO ₂ were used as starting materials. The title phosphor was synthesized by the method.

The brightness of this phosphor was compared with that of Ba _0.99 Sr _0.99 Eu _0.02 SiO ₄ , which was produced by the same method, and showed 147% at 365 nm, 159% at 400 nm and 187% at 450 nm. However, lower brightness was shown for wavelengths shorter than 280 nm.

The luminescence spectroscopy of the phosphor of this embodiment and the Ba _0.99 Sr _0.99 Eu _0.02 SiO ₄ phosphor have the same shape, but the excitation spectral distribution is different. Specifically, FIG. 4 compares the excitation spectral distributions of the two phosphors for 515 nm showing the maximum emission intensity.

According to the present invention, a portion of the alkaline earth metal sites of the existing (Ba _2-x Sr _x ) SiO ₄ : Eu ²⁺ phosphors is replaced with rare earth elements La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Substitute Ho, Er, Tm, Yb, Lu, Y, Sc, etc. with Al, Ga, In, etc. of Group 3 elements, and replace them with alkali metal ions Li, Na, K, etc. The luminous efficiency can be obtained more than 80% higher than conventional (Ba _2-x Sr _x ) SiO ₄ : Eu ²⁺ phosphors for 365 nm UV and UV near 370 nm.

Claims (5)

Phosphor of formula (I) using Europium as an activator <Formula 1> (Ba _2-xyz-α Sr _x Eu _y M _z N _α ) SiO _{4 + δ} In the above formula, x is 0 ≦ x <2, y is 0.001 ≦ y ≦ 0.05, z is 0.001 ≦ z ≦ 0.1, α is 0 ≦ α ≦ 0.1, and x + y + z + α is 0 ≦ x + y + z + α ≦ 2, δ is −0.05 ≦ δ ≦ 0.05, M is La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, Sc , Al, Ga, In, and N is Li, Na, K. A first heat treatment step of quantitatively weighing and grinding the starting material according to the composition of Formula 1, and then placing the starting material in an alumina crucible and heating it; A second heat treatment step of naturally cooling the first heat-treated sample in an electric furnace and then regrinding and heating the sample in a tubular electric furnace in which hydrogen gas or hydrogen and nitrogen mixed gas flows into a boat; And And naturally cooling the second heat-treated sample in a tubular electric furnace through which hydrogen gas or a mixture of hydrogen and nitrogen flows. <Formula 1> (Ba _2-xyz-α Sr _x Eu _y M _z N _α ) SiO _{4 + δ} In the above formula, x is 0 ≦ x <2, y is 0.001 ≦ y ≦ 0.05, z is 0.001 ≦ z ≦ 0.1, α is 0 ≦ α ≦ 0.1, and x + y + z + α is 0 ≦ x + y + z + α ≦ 2, δ is −0.05 ≦ δ ≦ 0.05, M is La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, Sc , Al, Ga, In, and N is Li, Na, K. The Si compound as a synthetic raw material is SiO ₂ having a purity of 99% or more, and Ba, Sr, Eu, La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm , Yb, Lu, Y, Sc, Al, Ga, In, etc. are in the form of nitrate, carbonate or oxide with purity of at least 99.9%, and Li, Na, K, etc. are in the form of carbonate with at least 99.9% purity. The method of claim 2, wherein the first heat treatment is performed at 700 ° C. to 1000 ° C. for 2 hours to 4 hours. The method of claim 4, wherein the second heat treatment is performed at 1000 ° C. to 1300 ° C. for 2 hours to 10 hours.