TWI512082B - A red nitride phosphor with high color rendering and high heat characteristics - Google Patents

Description

Red nitride phosphor with high color rendering and high thermal properties

The invention relates to a red nitride fluorescent powder, in particular to a red M ₂ Si ₅ N ₈ :Eu fluorescent powder material, wherein M is a common body of Ca, Sr and Ba, and is matched with blue LED and yellow fluorescent powder. Cocoa regulates the position of the light-emitting wavelength and the half-height width, and has the characteristics of high color rendering and high heat resistance.

In recent years, White Light-Emitting Diodes (WLEDs) are one of the next generations of emerging industries. They have the advantages of small size, small heat radiation, long life and low power consumption, which can solve the problem that incandescent bulbs are difficult to overcome. problem. Today's international growth based on the concept of energy conservation and environmental protection shows the market development value of white light-emitting diodes as a new generation of lighting. According to experts' evaluation, if incandescent bulbs are replaced by white light-emitting diodes, they can be saved every year. The amount of electricity generated by at least one power plant. Recently, Taiwan, where the nuclear plant was built, is an example. If one-fourth of the incandescent bulbs and fluorescent lamps in Taiwan are replaced by white light-emitting diodes, about 11 billion kilowatt-hours of electricity can be saved each year, equivalent to one year for nuclear power plants. The power generation has also attracted the attention of the public in the current development of new energy and energy efficiency. In the past ten years, color light-emitting diodes have been widely used in color lighting, displays, entertainment products, etc. Among them, the electronic display industry is the fastest growing field, and it is believed that the future application of optoelectronic components will play an important role.

Conventionally, U.S. Patent No. 5,998,925 discloses a first white light diode which is an ytterbium-doped yttrium aluminum garnet luminescent powder which is excited by a blue light emitting diode. The yellow light and blue light emitted by the fluorescent powder are mixed to produce white light. The most commonly used method for producing white light is to place a wavelength converting material such as yellow phosphor powder on the light emitting surface of the blue light emitting LED chip, and the wavelength converting material layer on the LED chip absorbs some photons emitted by the LED, and the photon is The photon is converted down to visible light wavelength, and then the blue and yellow wavelength light source is generated. The two-color light source has a certain proportion, which is closer to white light when viewed by the human eye. In recent years, the color light-emitting diode is used for display and entertainment production. It is quite common in the product, the white light-emitting diode must have a complete full-spectrum band, and the red spectrum is the current development direction.

According to the current international major LED manufacturers are moving towards RGB high color rendering white LEDs. To compensate for the red spectrum lacking YAG phosphor powder, the white LED process with red phosphor powder has become a new topic. The synthesis and application information of red fluorescent powder, the patent of Bogner et al. (US 6,649,946) of Osram, Germany, reveals M _x Si _y N _z :Eu (where M=Ca, Sr and Ba, z=2/3x+4/ 3y) Nitride can be used as a red phosphor material for LEDs. 1995, Schlieper et al. (T. Schlieper, W. Milius and W. Schnick, Z. anorg. allg. Chem. 621, 1995 , 1380-1384) synthesis and study of M ₂ Si ₅ N ₈ (M=Sr and Ba) Single crystal structure of nitride. The space groups of Ca ₂ Si ₅ N ₈ , Sr ₂ Si ₅ N ₈ and Ba ₂ Si ₅ N ₈ belong to Cc, Pmn21 and Pmn2, respectively, and the color rendering and heat resistance of red phosphor powder still need to be improved.

In view of the above-mentioned disadvantages of the prior art, the main object of the present invention is to provide a red M ₂ Si ₅ N ₈ :Eu phosphor powder having a high color rendering property and a high heat resistance characteristic (Ca, Sr and Ba) as a common body. material. Wherein, the composition of the red phosphor is Sr _2-xy (Ca _0.55 Ba _0.45 ) _x Si ₅ N ₈ :Eu ²⁺ _y (0<x<2;0<y<2;0<x+y< 2).

The invention adopts M ₃ N ₂ (wherein M comprises three kinds of Ca, Sr and Ba), Si ₃ N ₄ and EuN as synthetic raw materials, and the solid state synthesis method of metal ion radius ratio can reduce the lattice volume caused by different atom substitutions. The variation of the change, and holding the temperature at normal pressure or high pressure and high temperature for two hours, sintering synthesis of Sr _2-xy (Ca _0.55 Ba _0.45 ) _x Si ₅ N ₈ :Eu ²⁺ _y (0<x<2;0<y<2;0<x+y<2) red nitride phosphor. The invention is mainly composed of Sr _1.98 Si ₅ N ₈ :Eu ²⁺ _0.02 (ie y=0.02), and the special ratio of (Ba, Ca) is substituted for Sr, which can reduce the variation of lattice volume caused by different atom substitutions. And maintain the original crystal phase. In addition, the optical laser spectrum shows that the material can be excited by a light source of a wavelength range of 370 to 470 nm, indicating that the present invention can be applied to a red phosphor of a white light emitting diode, and the main peak produces a red shift from 613 nm to 633 nm, and a half height. The width is increased from 84 nm to 115 nm, indicating that the material has the characteristics of adjusting the position of the light-emitting wavelength and the width at half maximum to improve the color rendering property as a white light-emitting diode. In addition, through the temperature-dependent fluorescence spectrum, it is found that as the (Ba, Ca) substitution amount increases, the thermal characteristics gradually increase (i.e., have better heat resistance characteristics), and x = 1.5 is optimal. Color rendering is the percentage of the real feeling of an object under the light source and the feeling under the sun. The measurement standard is 100% true color with natural light Ra-100. The half-height width of the main peak wavelength can be known from the optical laser spectrum. The wider the width and width of the fluorescent powder, the more colors it emits, which contribute to the improvement of color rendering. Generally, it is applied to general illumination, and vice versa. The narrower the width and width, the more suitable for the display, the higher the resolution and the better the reproducibility of the color.

The above summary and the following detailed description are intended to further illustrate the manner, means and function of the present invention to achieve the intended purpose. Other objects and advantages of the present invention will be set forth in the description which follows.

The first figure is an X-ray powder diffraction pattern of a red nitride fluorescent powder according to an embodiment of the present invention.

The second figure is an excitation spectrum of the red nitride fluorescent powder of the embodiment of the present invention.

The third figure is a luminescence spectrum of the red nitride fluorescent powder of the embodiment of the present invention.

The fourth figure is a temperature-dependent emission spectrum of the red nitride fluorescent powder of the embodiment of the present invention.

The embodiments of the present invention are described below by way of specific examples, and those skilled in the art can readily appreciate the other advantages and advantages of the present invention.

Example

M ₃ N ₂ (where M contains Ca, Sr and Ba), Si ₃ N ₄ and EuN as synthetic raw materials, and sintered at a pressure of 0.5 Mpa and a temperature of 1600 ° C for two hours to synthesize Sr _2-xy (Ca _0.55 Ba _0.45 ) _x Si ₅ N ₈ :Eu2+ _y (0 x 1.98;y=0.02;0.02 x+y 2) Red nitride phosphor powder. The invention is mainly composed of Sr _1.98 Si ₅ N ₈ :Eu ²⁺ _0.02 (ie y=0.02), and the special ratio of (Ba, Ca) is substituted for Sr, which can reduce the variation of lattice volume caused by different atom substitutions. That is, Sr _1.98-x (Ca _0.55 Ba _0.45 ) _x Si ₅ N ₈ :Eu ²⁺ _0.02 (0) x 1.98;y=0.02;0.02 x+y 2) Red nitride phosphor powder formula. Referring to the first figure, the X-ray powder diffraction pattern of the red nitride fluorescent powder of the embodiment of the present invention is characterized, and the sintered phosphor powder is identified by X-ray powder diffraction analysis (XRD). Comparing with the red fluorescent powder of pure phase Sr _1.98 Si ₅ N ₈ :Eu ²⁺ _0.02 (x=0; y=0.02), it was found that the structure of the present embodiment is pure phase in the substitution amount x<1.5. When the substitution amount x=1.98, the crystal phase changes, and it can be known that the special substitution ratio (Ba, Ca) in place of Sr can reduce the variation of lattice volume caused by different atom substitutions. And maintain the original crystal phase.

Please refer to the second figure for the excitation spectrum of the red nitride fluorescent powder according to the embodiment of the present invention. The Sr _1.98-x (Ca _0.55 Ba _0.45 ) _x Si ₅ N ₈ :Eu ²⁺ _0.02 (prepared by the present invention) 0 x 1.98;y=0.02;0.02 x+y 2) Excitation spectrum of a series of red nitride phosphors, it is known that the red phosphor can be excited by a light source of a wavelength range of 370 to 470 nm, indicating that the present invention can be applied to a red phosphor of a white light emitting diode. Please refer to the third embodiment for the luminescence spectrum of the red nitride fluorescent powder according to the embodiment of the present invention. The spectrum is a normalized spectroscopy spectrum, wherein the value of the substitution amount x increases. The main peak produces a red shift from 613 nm to 633 nm, while the full width at half maximum increases from 84 nm to 115 nm. From the first, second and third figures, the red fluorescence of the control Sr _1.98 Si ₅ N ₈ :Eu ²⁺ _{0.02 is known} . When the powder and the red phosphor of the partial Sr are replaced by a special ratio of Ca and Ba, the crystal phase is not changed. When the substitution amount of Ca and Ba substituted Sr is increased, the main peak of the measured spectrum is red-shifted. Moreover, the width at half maximum is gradually wide, indicating that the present invention has the characteristics of regulating the main peak wavelength and the full width at half maximum.

Please refer to the fourth embodiment for the temperature-dependent emission spectrum of the red nitride fluorescent powder according to the embodiment of the present invention, which is the Sr _1.98-x (Ca _0.55 Ba _0.45 ) _x Si ₅ N ₈ :Eu ² prepared by the invention. ⁺ _0.02 (0 x 1.98;y=0.02;0.02 x+y 2) The variable temperature radiation spectrum diagram, as shown in the figure, can be seen that when the control does not replace part of Sr with Ca and Ba (ie, x=0), when the substitution amount x increases, the thermal characteristics gradually increase, and x=1.5 has the best heat resistance. Characteristics, this result shows that the present invention contributes to the problem of improving the thermal stability of the white light emitting diode.

The above-described embodiments are merely illustrative of the features and functions of the present invention and are not intended to limit the scope of the technical scope of the present invention. Modifications and variations of the above-described embodiments can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention should be as set forth in the scope of the claims described below.

Claims (10)

A red nitride phosphor with high color rendering and high thermal properties, the composition of which is M ₂ Si ₅ N ₈ :Eu, wherein the M system comprises three metals of Sr, Ca and Ba, and the Ca and Ba are replaced by special ratios. Sr, the intermetallic ratio of the phosphor is Sr _2-xy (Ca _0.55 Ba _0.45 ) _x Si ₅ N ₈ :Eu ²⁺ _y , where 0<x<2;0<y<2;0<x+y<2. A red nitride phosphor having high color rendering properties and high thermal properties as described in claim 1, wherein the phosphor powder is prepared by using M ₃ N ₂ , Si ₃ N ₄ and EuN, wherein M Contains three metals: Ca, Sr and Ba. A red nitride fluorescent powder having high color rendering property and high thermal property as described in claim 1, wherein 0<x<1.98 has the same crystal phase. A red nitride phosphor having high color rendering properties and high thermal characteristics as described in claim 1 wherein the phosphor powder is excited by a light source having a wavelength in the range of 370 to 470 nm. A red nitride phosphor having high color rendering properties and high thermal properties as described in claim 1, wherein the phosphor has a main light emission wavelength of 613 to 633 nm. A red nitride fluorescent powder having high color rendering property and high thermal property as described in claim 1, wherein when x=1.5, the color rendering property Ra is 87. A red nitride phosphor having high color rendering properties and high thermal properties as described in claim 1 wherein the optimum heat resistance is obtained when x = 1.5. A red nitride phosphor having high color rendering properties and high thermal properties as described in claim 1, wherein the phosphor powder can be synthesized under normal pressure or high pressure, wherein the high pressure means 0.5 MPa. A red nitride fluorescent powder having high color rendering property and high thermal property as described in claim 1, wherein the fluorescent powder system can adjust the wavelength of the light emitting wavelength and the full width at half maximum. A red nitride fluorescent powder having high color rendering properties and high thermal characteristics as described in claim 1, wherein the phosphor powder has a half-height width of the light-emitting wavelength of 84 nm to 115 nm.