KR100878351B1 - A novel red-emitting phosphor for the application to ultraviolet light emitting diode and cold cathode fluorescent lamp - Google Patents

Abstract

A red-emitting phosphor is provided to ensure high brightness and excellent chromatic purity under 200-500 nm excitation which is a long wavelength UV range and to be applied to a cold cathode fluorescent lamp and ultraviolet excitation light emitting diode. A red-emitting phosphor for a cold cathode fluorescent lamp and ultraviolet excitation light emitting diode has a composition of the chemical formula: [Na(Y_(1-x-y)Gd_x)GeO_4:Eu_y] and is excited in the long wavelength UV range of 200-500 nm. In the chemical formula, 0 <= x <= 0.525 and 0.175 <= y <= 0.7.

Description

A novel red-emitting phosphor for the application to ultraviolet light emitting diode and cold cathode fluorescent lamp

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to red phosphors for cold cathode fluorescent lamps (CCFLs) and ultraviolet-light emitting diodes (UV-LEDs), more particularly containing germanium oxides. By using europium (Eu) as an activator in the ceramic matrix, the high-efficiency red phosphor having excellent luminous luminance by a long wavelength ultraviolet excitation light source in the vicinity of 200 to 500 nm is provided. In particular, an excitation wavelength of 254 nm relates to a high efficiency red phosphor that can be useful for CCFL light emitting devices and an excitation wavelength of 400 nm can be useful for UV-LEDs.

Recently, the demand for and interest in alternative lighting and displays is increasing, and research on this is being actively conducted in various countries including Korea. In particular, a light emitting diode (LED) refers to a device that injects a small number of carriers using a pn junction structure of a semiconductor and emits light through recombination thereof, and is representative of red using GaAsP. Devices, green devices using GaP, and blue devices using InGaN. LEDs are characterized by low power consumption, long life and external physical vibration. Recently, a white light emitting diode using an LED has been released and used as a back light source and a lighting device of a liquid crystal display device.

There are two ways to implement white light using such an LED device.

The first is to mix white, green and blue LED chips to achieve white. However, this method has a disadvantage in that the chips are thermally deteriorated, and the characteristics of each chip deteriorated with time are different, so that the color tone is changed according to the use environment. In particular, since color spots occur depending on the use environment, uniform white is not realized, and manufacturing costs are also expensive.

The second method is to implement white light by applying YAG: Ce-based yellow phosphor on a blue LED substrate near 450 nm. That is, a part of the light emission of the LED chip and the light emission by the emitted phosphors are mixed to implement white color. This type of LED device is widely used as a back light source of LCD, lighting, notebook, mobile phone. However, since the light emitting device uses a blue LED as an excitation energy source, it is difficult to apply a fluorescent material for realizing a color other than white, and since the light emitting device has only a partial spectrum of the visible light region, color rendering is low.

Therefore, it is urgent to develop red, green and blue phosphors that can exhibit excellent light emission characteristics by using long-wavelength UV-LEDs as excitation energy sources. Particularly, in the case of red phosphors, fluorescent materials that are effectively excited around 400 nm have not been developed, and thus, there is a difficulty in application to lighting using UV-LEDs.

In the case of a phosphor having good long-wavelength UV efficiency, it is also very important for the development of an active light emitting liquid crystal display (LCD). In an active light emitting LCD, a display is realized by light emission by phosphors excited from a back light source. In this case, the back light source used should not damage the liquid crystal. Recently, a cold cathode fluorescent lamp (CCFL) and an LED having excellent device characteristics are used as the back light source.

CCFL is driven by a high voltage induced at both ends of the glass tube in which the quantitative mercury gas is mixed, and electrons present in the tube are attracted to the electrode (anode) to move at a high speed, and secondary electrons are emitted to discharge the discharge. Electrons flowing by the discharge collide with mercury atoms in the tube to generate ultraviolet rays (254 nm), and the ultraviolet rays excite the fluorescent material applied to the inner wall of the glass tube to emit visible light. A liquid crystal display using a conventional CCFL using a phosphor as a light source has a problem of low color reproducibility and color purity, resulting in poor color balance. More specifically, blue had no problem in color purity, but green and red tended to have low color purity. Therefore, improvement of color purity is desired in order to be used as a display display.

Include Eu _{0 .5,} Sm _{0 .07} and europium: the red fluorescent body is 3.5MgO-0.5MgF ₂ -GeO ₂ developed in order to use a long-wavelength UV excitation energy source to date by: Mn and Li (WO _{4) 1.25} Although there were sulfides and nitrides added, such red phosphors had low light emission luminances, and particularly had low light emission efficiency at an excitation energy source of 400 nm or more. In addition, there was a problem that the white light is difficult to implement due to the low brightness of the red light itself, and the red phosphor for the purpose of the application as CCFL and UV-LED is difficult to be practical.

The present invention uses europium (Eu) as an activator in a ceramic matrix containing germanium (Ge) -based oxide, thereby providing a highly efficient red phosphor having excellent emission luminance and color purity in the long wavelength ultraviolet range of 200 to 500 nm. Its purpose is to. In addition, an object of the present invention is to provide a light emitting device such as CCFL and UV-LED containing the red phosphor.

The present invention provides a red phosphor for a cold cathode fluorescent lamp (CCFL) and an ultraviolet-excited light emitting diode (UV-LED) which has a composition of the following Chemical Formula 1 and is excited in a long wavelength ultraviolet (UV) region in the range of 200 to 500 nm. .

Na (Y _1-xy Gd _x ) GeO ₄ : Eu _y

In Formula 1, 0 ≦ x ≦ 0.525, and 0.175 ≦ y ≦ 0.7.

The red phosphor according to the present invention has an effect of excellent luminance characteristics and color purity under 200-500 nm excitation, which is a long wavelength ultraviolet region. In particular, since the light emission characteristics at the excitation wavelength 254 nm and 400 nm are excellent, it is expected to be applied to applications such as CCFL and UV-LED.

The present invention relates to a red phosphor which has high brightness under a long wavelength ultraviolet ray region of 200 to 500 nm excitation and is excellent in color purity and can be usefully applied to CCFL and UV-LED.

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

The red phosphor of the present invention is a composition already known (Korean Patent Publication No. 2001-0062527).

In general, since phosphors have different physical properties required according to the field of use, specifically, suitable phosphors exist separately according to applications such as PDP, LED, CCFL, FED, CRT, and EL, which are used for phosphors. Known as Particularly, PDP, LED, CCFL, etc. using the photoexcitation process have different required excitation wavelengths and different phosphor synthesis conditions for maximum efficiency, and the phosphors applied thereto emit light by different excitation wavelengths, It is generally known that the synthesis conditions of the phosphors are different.

Specifically, in the PDP field, the CCFL uses a red phosphor that uses a wavelength of 147 nm as an excitation source at a high vacuum of 10 ^-2 torr or less, that is, a vacuum that uses vacuum ultraviolet (Vacuum Ultra Violet, VUV) as an excitation source. Silver uses a red phosphor that uses ultraviolet rays having a wavelength of 254 nm, which is a characteristic wavelength of mercury element, as an excitation source at 50 to 70 torr having a relatively low degree of vacuum, and uses a wavelength of 400 nm at normal pressure. Due to the difference in the excitation energy and the degree of vacuum, the range of concentration quenching of the active element with respect to the luminous efficiency is greatly different, and also gadolinium (Gd) as an additive to help the emission of the active element Europium (Eu). The ratio of the element also acts as an important variable, and the active element concentration range and the composition of the phosphor raw materials having optimum efficiency under each excitation condition are different. In addition, even when the compounds of the same composition are used, the luminance characteristics of the phosphors appear completely different under different excitation conditions of vacuum ultraviolet rays and ultraviolet rays. Therefore, since the red phosphor according to the present invention is a phosphor in a completely different field from the conventional red phosphor for PDP, a person of ordinary skill in the art will never judge that the red phosphor for PDP is simply inverted into CCFL or UV-LED. It is obvious that it is not easy.

In addition, phosphor synthesis conditions also show different efficiency characteristics according to excitation conditions. In the case of the red phosphor according to the Republic of Korea Patent Publication No. 2001-0062527 exhibited the maximum efficiency characteristics by heat treatment for 24 hours at a temperature of about 950 ℃, in the case of the present invention heat treatment for 12 hours at a temperature of about 1100 ℃ or more In other words, it exhibited maximum efficiency at relatively high temperature synthesis conditions. This is because the phosphor of the present invention has a composition where the excitation area of the phosphor is narrower and the concentration quenching range is relatively larger than that of the vacuum ultraviolet ray of the present invention. It acts as a center of stable light emission within.

Therefore, the present invention is not characterized in the technical configuration of the novel red phosphor, but is characterized in that it is applied to new applications specifically CCFL and LED devices.

The present invention will be described in more detail as follows.

In the present invention, a germanium oxide (Ge) -based oxide is selected and used as a matrix of the phosphor, for example, a germanium oxide including sodium, yttrium or gadolinium, which are known materials as the mother of the red phosphor. In particular, in the present invention, by adding at least one element selected from yttrium and gadolinium to the germanium-based oxide matrix, the effect of assisting light emission of the active element europium (Eu) is obtained. Therefore, the composition ratio of Chemical Formula 1 is maintained in consideration of the characteristics of light emission luminance and color purity.

In Figure _{1 Na (Y 0 .3 Gd 0} .2) GeO 4 according to the invention: Eu _{0 .5} conventional Y ₂ O ₃ is now commercially available fluorescent materials: in order to compare with Eu phosphor (Phosphor Technology, Inc.), light Excitation absorption spectrum (Photoluminescence, PL) was measured. As a result, it was confirmed that the Na (Y _0.3 Gd _0.2 ) GeO ₄ : Eu _0.5 red phosphor according to the present invention generates a peak excited between 450 to 750 nm region, particularly at wavelengths of 254 nm and 400 nm. Could. However, although the conventional Y ₂ O ₃ : Eu red phosphor has the same level of excitation efficiency at a wavelength of 254 nm, it was confirmed that it is very weakly excited at a wavelength of 400 nm compared with the red phosphor of the present invention. This is the reason why the light emission characteristics of the conventional red phosphor were not good. Therefore, the red phosphor according to the present invention has particularly excellent excitation characteristics at wavelengths of 254 nm and 400 nm of ultraviolet light, and the excitation wavelength of 254 nm can be usefully used for CCFL light emitting devices, and the excitation wavelength of 400 nm is UV-LED. This can be usefully used.

The red phosphor represented by Chemical Formula 1 according to the present invention uses a conventional method used in the art, for example, sodium (Na) and germanium (Ge) precursors to yttrium (Y) or gadolinium (Gd). ) 1 step of preparing a mixture by weighing a precursor and a europium (Eu) precursor, 2 steps of drying the mixture in the range of 100 ~ 150 ℃ and 3 steps of heat treatment of the dried mixture at 1000 ~ 1200 ℃ Can be.

First, the sodium (Na) and germanium (Ge) precursors and the yttrium (Y) or gadolinium (Gd) precursors and the europium (Eu) precursors are weighed to have the composition of Chemical Formula 1 to prepare a mixture. At this time, the precursor of the elements is not particularly limited to precursors commonly used in the art, for example, sodium precursor (Na ₂ CO ₃ ) and hydrates thereof may be used as a precursor of sodium, as a precursor of germanium Germanium oxide (GeO ₂ ) may be used, and precursors of yttrium and gadolinium may be oxides (Y ₂ O ₃ , Gd ₂ O ₃ ), nitrates, and the like. In addition to the active agents of the europium precursor may be used as the flow path width oxide (Eu ₂ O _3).

The mixture of precursors is sufficiently mixed to have a uniform composition using a solvent selected from acetone, alcohol and water for more effective mixing, and using a mixing device such as ball milling or agate induction. The solvent is used in the range of 100 to 500% by weight relative to the precursor mixture. If the amount of the solvent is less than 100% by weight, it is difficult to form the precursor mixture in the slurry phase. It is preferable to maintain the above range because a problem occurs that the solvent removal process of the solvent is not easily performed.

Next, the solvent in the mixture is dried and dried at 100 to 150 ° C., more preferably at 120 to 130 ° C. for 1 to 24 hours, in order to completely remove moisture and organic solvents to effectively induce a chemical reaction. If the drying temperature is less than 100 ℃, it is difficult to completely remove the solvent used, and if it exceeds 150 ℃ it is included in the temperature range of the boiling point or more of the solvent used to cause the phenomenon that the solvent is boiled, there is a fear that the phosphor film is lost. It is preferable to maintain the above range because it is not easy in operation.

Next, the dried mixture is heat treated at a temperature of 1000 to 1200 ° C. for up to 16 hours. More preferably, the heat treatment is performed for 8 to 12 hours at a temperature of 1000 to 1100 ℃ in consideration of particle aggregation and grinding characteristics. The method of the heat treatment is not particularly limited to a method generally used in the art, for example, may be performed by using an electric furnace after adding the dried mixture to a high purity alumina boat. At this time, if the firing temperature is less than 1000 ℃, the substitution of the europium activator and the Y, Gd element is not completely made, if it exceeds 1200 ℃, agglomeration occurs between the phosphor particles, causing a problem that the brightness characteristics are deteriorated Therefore, it is preferable to maintain the above range. The heat-treated phosphor can be pulverized to various sizes through a post-treatment process, such pulverization is performed by a method commonly used in the art, for example, can be used, such as a mortar, ball mill.

As described above, the red phosphor according to the present invention, by adding europium (Eu) to the germanium (Ge) -based oxide as an activator, the CCFL and the excellent luminescence brightness in the long wavelength ultraviolet range of 200 ~ 500 nm range It can be usefully applied to light emitting devices such as UV-LEDs.

Hereinafter, the present invention will be specifically described based on the following examples, but the present invention is not limited by the following examples.

Example 1 Preparation of Na (Y _0.3 Gd _0.2 ) GeO ₄ : Eu _0.5 Phosphor

Sodium carbonate, yttrium oxide, gadolinium oxide, germanium oxide and europium oxide were weighed in the above ratio so that the molar ratio of sodium: yttrium: gadolinium: germanium: europium ions was 1: 0.3: 0.2: 1: 0.5, and acetone was added thereto. After the addition, the mixed sample was prepared by mixing sufficiently evenly using agate mortar. The prepared mixed sample was dried at 120 ° C. for 1 hour using an oven. The mixture obtained above was placed in a high-purity alumina boat and heat-treated at an ambient temperature of 1100 ° C. for 12 hours using an electric furnace, and then sufficiently ground to give a red phosphor having a composition of Na (Y _0.3 Gd _0.2 ) GeO ₄ : Eu _0.5 . Was prepared.

Examples 2-11: Preparation of Na (Y _0.5-x Gd _x ) GeO ₄ : Eu _0.5 phosphor

The synthesis was carried out as Example 1, the composition was fixed to 0.5 mol of the europium changing the molar ratio of yttrium and gadolinium _{Na (Y 0 .5- x Gd x} ) GeO 4: to prepare a red phosphor of Eu _{0 .5} .

Examples _{12 ~ 21: Na (Y 0} .3 Gd 0 .7-x) GeO 4: Eu x Preparation of Phosphor

The synthesis was carried out as Example 1, a fixed yttrium 0.3 mol and by changing the molar ratio of gadolinium and europium composition of _{Na (Y 0 .3 Gd 0 .7} -x) GeO 4: to prepare a red phosphor of Eu _x .

Comparative Example 1

The commercially available (Y, Gd) BO ₃ : Eu red phosphor for PDP (Plasma Display Panel) of the crystal was compared with the examples of the present invention.

Comparative Example 2

Commercially available Y ₂ O ₃ : Eu red phosphor for CCFL from Phosphor Technology Inc. was compared with an embodiment of the present invention.

Experimental Example  One

The phosphors provided in Examples 1 to 21 and Comparative Examples 1 and 2 were observed for absorption and emission spectra using a monochromator and a photomultiplier tube (PSI) in a wavelength range of 200 to 500 nm. The color coordinate values were obtained using the same system.

division Y (mol) Gd (mol) Eu (mol) Relative luminance (%) compared to Y ₂ O ₃ commercial phosphor (254 nm excitation) Relative luminance (%) compared to (Y, Gd) BO ₃ commercial phosphor (147 nm excitation) Example 1 0.3 0.2 0.5 99 5 Example 2 0.5 0 0.5 75 4 Example 3 0.45 0.05 0.5 92 7 Example 4 0.4 0.1 0.5 95 4 Example 5 0.35 0.15 0.5 95 3 Example 6 0.25 0.25 0.5 91 4 Example 7 0.2 0.3 0.5 83 5 Example 8 0.15 0.35 0.5 75 5 Example 9 0.1 0.4 0.5 77 4 Example 10 0.05 0.45 0.5 73 3 Example 11 0 0.5 0.5 76 3 Comparative Example 1 Y ₂ O ₃ : Eu 100 - Comparative Example 2 (Y, Gd) BO ₃ : Eu - 100

As can be seen from Table 1, in the phosphors corresponding to Examples 1 to 11 of the present invention, Y ₂ O ₃ which is a red phosphor for commercial CCFLs in the ultraviolet region of 254 nm which is the excitation energy source of CCFLs : Compared with Eu (Comparative Example 1), the relative luminance was at least 70%. Although the luminance characteristic of the present invention is somewhat lower than that of the conventional red phosphor, the luminance is sufficient to be used as a commercially available red phosphor for CCFL. The red phosphor of the present invention is suitable for use as a phosphor for CCFL. In addition, the red phosphor according to the present invention has the advantage that can be used alone or mixed with commercially available CCFL red phosphor is improved color purity characteristics as shown in Table 2.

On the other hand, the red phosphor of the present invention is (Y, Gd) BO _{3 which is a} red phosphor for commercial PDP in the vacuum ultraviolet region of 147 nm which is an excitation energy source of PDP. : Compared with Eu (Comparative Example 2), the relative luminance was less than 7%. From these results, the CCFL red phosphor of the present invention shows completely different luminance characteristics depending on excitation energy sources such as ultraviolet rays and vacuum ultraviolet rays, even though the composition is the same as that of the PDP red phosphor. It was confirmed that this is a completely different field for the purpose that cannot be used. In addition, although the red phosphor composition of the present invention is included in the composition range of the red phosphor disclosed in Korean Patent Laid-Open No. 2001-0062527 from the results of Table 1, all the red phosphors present in the conventional red phosphor composition range are used for PDP. It was confirmed that it does not show excellent characteristics.

Therefore, the red phosphor of the present invention is selected from the red phosphor of the Republic of Korea Patent Publication No. 2001-0062527, in particular, used only for the CCFL and LED by selecting the red phosphor having the characteristic of being excited from ultraviolet rays of 254 nm and 400 nm, The two red phosphors can be confirmed once again through Examples 1 to 11 and Comparative Examples 1 and 2 that there are completely different application differences due to the difference in the excitation energy source.

division Y (mol) Gd (mol) Eu (mol) % Relative luminance at 614 nm with 400 nm excitation CIE x CIE y Example 1 0.3 0.2 0.5 356 0.655 0.339 Example 2 0.5 0 0.5 199 0.654 0.339 Example 3 0.45 0.05 0.5 265 0.654 0.339 Example 4 0.4 0.1 0.5 276 0.654 0.339 Example 5 0.35 0.15 0.5 226 0.654 0.339 Example 6 0.25 0.25 0.5 255 0.654 0.339 Example 7 0.2 0.3 0.5 231 0.654 0.339 Example 8 0.15 0.35 0.5 192 0.653 0.339 Example 9 0.1 0.4 0.5 182 0.655 0.339 Example 10 0.05 0.45 0.5 196 0.655 0.339 Example 11 0 0.5 0.5 203 0.655 0.339 Example 12 0.3 0 0.7 133 0.651 0.339 Example 13 0.3 0.05 0.65 209 0.654 0.339 Example 14 0.3 0.1 0.6 251 0.655 0.339 Example 15 0.3 0.15 0.55 285 0.655 0.339 Example 16 0.3 0.25 0.45 318 0.654 0.339 Example 17 0.3 0.3 0.4 288 0.654 0.339 Example 18 0.3 0.35 0.35 283 0.654 0.339 Example 19 0.3 0.45 0.25 270 0.655 0.339 Example 20 0.3 0.5 0.2 233 0.654 0.339 Example 21 0.3 0.525 0.175 196 0.653 0.339 Comparative Example 1 Y ₂ O ₃ : Eu 100 0.647 0.344

Table 2 shows Examples 1 to 21 when the maximum emission luminance (@ 614 nm) of Comparative Example 1, which is a conventional red phosphor for LEDs, when light having a wavelength of 400 nm was used as an excitation energy source. Relative luminance is shown relatively. As shown in Table 2, the germanium-based red phosphors prepared in Examples 1 to 21 according to the present invention had a relative luminance value of up to 3.5 times the luminance of the phosphor of Comparative Example 1 when the excitation wavelength was 400 nm. Could confirm.

In addition, the color coordinate characteristic was confirmed to have improved color purity characteristics by moving the conventional color coordinate from (X, Y) = (0.647,0.344) to (X, Y) = (0.655,0.339).

2 is a light emission spectrum showing a comparison of the PL relative intensity according to the irradiation of long wavelength ultraviolet rays excited at 254 nm wavelength, Figure 3 is a light emission shown by comparing the PL relative intensity according to the irradiation of long wavelength ultraviolet rays excited at a wavelength of 400 nm Spectrum. As can be seen in Figure 2, in the emission spectrum according to the 254 nm long wavelength excitation, it was confirmed that the red phosphor according to Example 1 of the present invention is superior to the conventional red phosphor, the light emission according to the 400 nm long wavelength excitation In the spectrum, it was confirmed that the red phosphor according to Example 1 of the present invention was significantly superior in luminescence properties as compared with the conventional red phosphor.

4 shows the relative luminance of the red phosphor prepared according to the content change of europium and gadolinium by fixing the yttrium content of Examples 12 to 21 according to the present invention to 0.3 mol and then irradiating a long wavelength of 254 nm. When the content of the europium is more than 0.5 mole, it was confirmed that the concentration quenching effect that causes the non-luminous transition due to the energy overlap between the light emitting elements occurs to reduce the light emission luminance.

1 _{Na (Y 0 .5- x Gd x} ) GeO 4: the excitation spectrum showing the relative PL intensity of the wavelength range between 500 ㎚ change from a red phosphor 200 ㎚ represented by Eu _{0 .5.}

2 is _{Na (Y 0 .5- x Gd x} ) GeO 4: an emission spectrum of the light when in the red phosphor represented by Eu _{0 .5,} where a wavelength of 254 ㎚ ultraviolet irradiation.

3 is _{Na (Y 0 .5- x Gd x} ) GeO 4: an emission spectrum of the light when in the red phosphor represented by Eu _{0 .5,} where long-wavelength ultraviolet light with a wavelength of 400 ㎚ irradiation.

4 is _{Na (Y 0 .5- x Gd x} ) GeO 4: In the red phosphor represented by Eu _{0 .5,} this shows the relative change in luminance according to the amount of europium in the ultraviolet ray-excited condition of the wavelength 254 ㎚.

Claims (2)

A red phosphor for a cold cathode fluorescent lamp (CCFL) and an ultraviolet-excited light emitting diode (UV-LED) which has a composition of Formula 1 and is excited in a long wavelength ultraviolet (UV) region in the range of 200 to 500 nm: [Formula 1] Na (Y _1-xy Gd _x ) GeO ₄ : Eu _y In Formula 1, 0 ≦ x ≦ 0.525, and 0.175 ≦ y ≦ 0.7. According to claim 1, wherein the red phosphor is _{Na (Y 0 .3 Gd 0 .2} ) GeO 4: Eu 0 .5, NaY 0 .5 GeO 4: Eu 0 .5, Na (Y 0.45 Gd 0.05) GeO 4 _{: Eu 0.5, Na (Y 0} .4 Gd 0 .1) GeO 4: Eu 0 .5, Na (Y 0.35 Gd 0.15) GeO 4: Eu 0.5, Na (Y 0 .25 Gd 0 .25) GeO 4: _{Eu 0 .5, Na (Y 0} .2 Gd 0 .3) GeO 4: Eu 0 .5, Na (Y 0.15 Gd 0.35) GeO 4: Eu 0.5, Na (Y 0 .1 Gd 0 .4) GeO 4 _{: Eu 0 .5, Na (Y} 0 .05 Gd 0 .45) GeO 4: Eu 0 .5, NaGd 0.5 GeO 4: Eu 0.5, NaY 0 .3 GeO 4: Eu 0 .7, Na (Y 0. _{3 Gd 0 .05) GeO 4:} Eu 0 .65, Na (Y 0 .3 Gd 0 .1) GeO 4: Eu 0 .6, Na (Y 0.3 Gd 0.15) GeO 4: Eu 0.55, Na (Y 0.3 Gd _0.25 ) GeO ₄ : Eu _0.45 , Na (Y _0.3 Gd _0.3 ) GeO ₄ : Eu _0.4 , Na (Y _0.3 Gd _0.2 ) GeO ₄ : Eu _0.5 , Na (Y _0.3 Gd _0.35 ) GeO ₄ : Eu _0.35 , Na ( Y _0.3 Gd _0.45 ) GeO ₄ : Eu _0.25 , Na (Y _0.3 Gd _0.5 ) GeO ₄ : Eu _0.2 and Na (Y _0.3 Gd _0.525 ) GeO ₄ : Eu _0.175 for cold cathode fluorescent lamp (CCFL) And red phosphors for ultraviolet excitation light emitting diodes (UV-LEDs).

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