CN105217953A - White-light emitting diode rare earth doped luminescent glass and preparation method thereof - Google Patents

Abstract

A rare earth-doped luminescent glass for a white light-emitting diode and a preparation method thereof. Rare earth Pr ³⁺ , Ho ³⁺ as the main luminescent ions are co-doped in the fluoride glass matrix, and the 445nm blue LED is excited to emit white light. The preparation method of the glass of the present invention comprises three steps of selecting raw materials, mixing glass batch materials and glass melting. The glass of the invention can be effectively excited by the blue light emitting diode to output white light. The rare earth-doped luminescent glass of the present invention is a multi-component ZrF ₄ -ZnF ₂ glass, and compared with ZBLAN glass, it has the advantages of higher glass transition temperature, better chemical and mechanical properties, and high luminous efficiency. Compared with YAG:Ce fluorescent powder, the luminescent glass of the present invention has the advantages of simple preparation method, easy operation and low cost.

Description

Rare earth-doped luminescent glass for white light emitting diode and preparation method thereof

technical field

The invention relates to the field of optoelectronics and lighting engineering technology, in particular to a rare earth-doped luminescent glass for a white light-emitting diode (hereinafter referred to as LED) and a preparation method thereof.

technical background

In the 1990s, breakthroughs in blue LED and long-wave ultraviolet excitation diode technology greatly promoted the development of white LED and became a major achievement in the fields of optoelectronics and lighting engineering technology. The development of lighting sources has three major categories: incandescent bulbs, ordinary and compact fluorescent lamps, and various types of high-intensity discharge lamps (HID). They have their own advantages and disadvantages, but in comparison, LED lighting has the characteristics of high efficiency, energy saving and long life, and is a new generation of lighting sources.

Currently on the market, blue LED chips combined with YAG:Ce yellow phosphor are the most common white LED products, and have become the mainstream of white LEDs. However, the fluorescent powder directly coated on the surface of the LED chip is prone to aging and light decay due to the influence of temperature, and it is not easy to disperse uniformly and cause light spots, and YAG:Ce lacks red light components, resulting in low color rendering index, which is not conducive to the lighting application of white LEDs. , in addition, the cost of this method is high, and the preparation process is relatively complicated, so the fluorescent glass applied to far-field excitation is considered to be the most promising solution to this problem.

In recent years, reports on improving white LED luminescent materials have been common. For example, some scholars have synthesized Er ³⁺ /Sm ³⁺ co-doped oxyfluoride glass system, which can generate white light under the excitation of ultraviolet light, but its physical and chemical properties are unstable. In addition, rare earth single-doped or co-doped silicates and phosphate glass luminescent materials are used instead of phosphors for white LEDs, which improves the luminous quality and stability of the luminescent materials, but the luminous intensity is low. In order to solve these problems, it is necessary to develop a luminescent material that has a suitable color temperature while emitting white light, and can be used as home lighting.

Fluoride glass has become a high-performance material for infrared optical applications due to its high transparency and low phonon energy, which can reduce the probability of non-radiative transition processes. Compared with many scholars at home and abroad at present, Pr ³⁺ is used as a luminescent ion to produce white light, but its development is limited due to the problem of insufficient green light emission, while the luminescence of Ho ³⁺ in the visible band is mainly concentrated at 540nm. In the green light area, the introduction of Ho ³⁺ can make up for the shortage of Pr ³⁺ in the application of white light emitting ions.

Contents of the invention

The object of the present invention is to provide a rare earth-doped luminescent glass for white light-emitting diodes (hereinafter referred to as LED) and a preparation method thereof. The glass has the characteristics of low porosity, high environmental stability and low cost.

The technical scheme adopted in the present invention is:

A rare earth-doped fluoride glass for white light LED, characterized in that the structural formula of the glass is as follows:

(50-x)ZrF ₄ -xZnF ₂ -33BaF ₂ -10YF ₃ -7AlF ₃ :yRe ³⁺

Wherein, the value range of x is 0-20, the value range of y is 0.2-4, and Re is co-doped with Pr ³⁺ and Ho ³⁺ .

The sum of the molar percentage concentrations of the above-mentioned raw material components is 100 mol%, the purity of each of the above-mentioned raw materials is analytically pure, and the rare earth compounds are PrF ₃ , HoF ₃ .

The present invention also provides a preparation method of the rare earth-doped fluoride glass for white light LED, comprising the following steps:

① Select the composition and its mole percentage according to the structural formula of the rare earth-doped fluoride glass, calculate the weight of each glass composition, and accurately weigh each raw material. The ZrF ₄ is composed of H ₈ F ₆ N ₂ Zr The other components are introduced by ZnF ₂ , BaF ₂ , YF ₃ , AlF ₃ , the rare earth ions are introduced by PrF ₃ , HoF ₃ , and the purity of the raw materials is 99.9%;

② Grind the weighed raw materials in a mortar and mix them evenly to form a mixture;

③ Put the mixture into a platinum crucible and melt it in a silicon carbon rod electric furnace at 900-950°C, keep it warm for 10-20 minutes to obtain molten glass, and clarify the molten glass for 10-25 minutes;

④Take out the platinum crucible, and pour the clarified glass liquid on the stainless steel mold preheated to 300-330°C to obtain colorless and transparent glass;

⑤ Move the glass into a muffle furnace whose temperature has been raised to 10°C-25°C lower than the transition temperature for annealing treatment, keep it warm for 4-8 hours, and then lower it to room temperature at a rate of 10-25°C/hour to obtain rare earth doped Fluoride glass.

Technical effect of the present invention:

Rare earth doped fluoride glass for white LED: (50-x)ZrF ₄ -xZnF ₂ -33BaF ₂ -10YF ₃ -7AlF ₃ :yRe ³⁺ . By adjusting the doping concentration and doping ratio of rare earth ions, the intensity of red, green, and blue light emitted by rare earth ions can be changed, and the color coordinates can be adjusted to obtain white light with different color temperatures.

The luminescent centers of Pr ³⁺ ions in the visible band are mainly located at 486nm in blue light and 606, 638nm in red light, while the luminescent centers of Ho ³⁺ ions are mainly in the green light region of 540nm. The addition of Ho ³⁺ ions can make up for the lack of green light when Pr ³⁺ ions are used as white light-emitting ions, so when two ions exist at the same time, red, green, and blue emissions can be produced, and the composite emits white light. When the doping concentration of rare earth ions is too high, it is easy to produce concentration quenching effect, so the doping concentration of rare earth ions is required to be within a moderate range. Therefore, when y=1-4, the luminous brightness and emission spectrum of the glass can satisfy the excitation of 445nm blue LED to produce white light. Among them, considering the strong luminescence of Pr ³⁺ and the wide luminescence range, the concentration of Pr ³⁺ is fixed, and the concentration of Ho ³⁺ is changed in a small range to adjust the emission ratio of RGB, which is easy to adjust the color by considering a variable. coordinates to obtain white light with different color temperatures.

The emission spectrum of the luminescent glass of the present invention covers the entire visible light region from 470nm to 750nm, and is a new type of material with high color rendering index, adjustable color temperature and very suitable for white LEDs. Compared with ZBLAN glass, the multi-component ZrF ₄ -ZnF ₂ glass of the present invention has the advantages of higher glass transition temperature, better chemical and mechanical properties and high luminous efficiency. Compared with YAG:Ce fluorescent powder, the luminescent glass of the present invention has the advantages of simple preparation method, easy operation and low cost.

Description of drawings

Figure 1 is the excitation spectrum at a wavelength of 480nm of sample 1Pr ³⁺ and 0.5Ho ³⁺ co-doped.

Fig. 2 is the emission spectrum of sample 1Pr ³⁺ and 0.5Ho ³⁺ co-doped under 443nm excitation.

detailed description

The glass composition of 12 specific examples of rare earth-doped fluoride glass for white light LED of the present invention is shown in the following table

Table 1: Glass formulations of 12 specific examples

Embodiment 1#:

The raw material composition is as shown in Table 1#, and the specific preparation process is as follows:

According to the molar percentage of the 1# glass composition in the table, calculate the corresponding weight percentage of each composition, weigh each raw material and mix them evenly; put the mixed material into a platinum crucible and melt it in a silicon carbide rod electric furnace at 900 °C until it is completely melted After clarifying for 10 minutes, pour the molten glass on the preheated mold at 300°C; quickly move the glass into a muffle furnace that has been heated to 330°C for annealing, keep it warm for 4 hours, and then lower it to room temperature at a rate of 10°C/hour , and the glass sample was taken out after complete cooling to obtain a rare earth doped fluoride glass.

Embodiment 2#:

The raw material composition is as shown in Table 2#, and the specific preparation process is as follows:

According to the molar percentage of the 2# glass composition in the table, calculate the corresponding weight percentage of each composition, weigh each raw material and mix them evenly; put the mixed material into a platinum crucible and melt it in a silicon carbide rod electric furnace at 910°C until completely melted After clarifying for 15 minutes, pour the molten glass on the mold preheated at 300°C; quickly move the glass into a muffle furnace that has been heated to 340°C for annealing, keep it warm for 6 hours, and then lower it to room temperature at a rate of 10°C/hour , and the glass sample was taken out after complete cooling to obtain a rare earth doped fluoride glass.

Embodiment 3#:

The raw material composition is as shown in Table 3#, and the specific preparation process is as follows:

According to the molar percentage of the 3# glass composition in the table, calculate the corresponding weight percentage of each composition, weigh each raw material and mix them evenly; put the mixed material into a platinum crucible and melt it in a silicon carbide rod electric furnace at 920°C until completely melted After clarifying for 15 minutes, pour the molten glass on the mold preheated at 320°C; quickly move the glass into a muffle furnace that has been heated to 340°C for annealing, keep it warm for 6 hours, and then lower it to room temperature at a rate of 15°C/hour , and the glass sample was taken out after complete cooling to obtain a rare earth doped fluoride glass.

Embodiment 4#:

The raw material composition is as shown in Table 4#, and the specific preparation process is as follows:

According to the molar percentage of the 4# glass composition in the table, calculate the corresponding weight percentage of each composition, weigh each raw material and mix them evenly; put the mixed material into a platinum crucible and melt it in a silicon carbide rod electric furnace at 930°C until completely melted After clarifying for 20 minutes, pour the molten glass on the preheated mold at 320°C; quickly move the glass into a muffle furnace that has been heated to 340°C for annealing, keep it warm for 6 hours, and then lower it to room temperature at a rate of 15°C/hour , and the glass sample was taken out after complete cooling to obtain a rare earth doped fluoride glass.

Embodiment 5#:

The raw material composition is as shown in Table 5#, and the specific preparation process is as follows:

According to the molar percentage of the 5# glass composition in the table, calculate the corresponding weight percentage of each composition, weigh each raw material and mix them evenly; put the mixed material into a platinum crucible and melt it in a silicon carbide rod electric furnace at 950°C until completely melted After clarifying for 25 minutes, pour the molten glass on the preheated mold at 330°C; quickly move the glass into a muffle furnace heated to 350°C for annealing, keep it warm for 8 hours, and then lower it to room temperature at a rate of 25°C/hour , and the glass sample was taken out after complete cooling to obtain a rare earth doped fluoride glass.

Embodiment 6#:

The raw material composition is as shown in Table 6#, and the specific preparation process is as follows:

According to the molar percentage of the 6# glass composition in the table, calculate the corresponding weight percentage of each composition, weigh each raw material and mix them evenly; put the mixed material into a platinum crucible and melt it in a silicon carbide rod electric furnace at 930°C until completely melted After clarifying for 20 minutes, pour the molten glass on the preheated mold at 310°C; quickly move the glass into a muffle furnace that has been heated to 340°C for annealing, keep it warm for 6 hours, and then lower it to room temperature at a rate of 10°C/hour , and the glass sample was taken out after complete cooling to obtain a rare earth doped fluoride glass.

Embodiment 7#:

The raw material composition is as shown in Table 7#, and the specific preparation process is as follows:

According to the molar percentage of the 7# glass composition in the table, calculate the corresponding weight percentage of each composition, weigh each raw material and mix them evenly; put the mixed material into a platinum crucible and melt it in a silicon carbide rod electric furnace at 930°C until completely melted After clarifying for 20 minutes, pour the molten glass on the preheated mold at 310°C; quickly move the glass into a muffle furnace that has been heated to 340°C for annealing, keep it warm for 6 hours, and then lower it to room temperature at a rate of 10°C/hour , and the glass sample was taken out after complete cooling to obtain a rare earth doped fluoride glass.

Embodiment 8#:

The raw material composition is as shown in Table 8#, and the specific preparation process is as follows:

According to the molar percentage of the 8# glass composition in the table, calculate the corresponding weight percentage of each composition, weigh each raw material and mix them evenly; put the mixed material into a platinum crucible and melt it in a silicon carbide rod electric furnace at 940°C until completely melted After clarifying for 20 minutes, pour the molten glass on the mold preheated at 320°C; quickly move the glass into a muffle furnace that has been heated to 340°C for annealing, keep it warm for 6 hours, and then cool it down to room temperature at a rate of 10°C/hour , and the glass sample was taken out after complete cooling to obtain a rare earth doped fluoride glass.

Embodiment 9#:

The raw material composition is as shown in Table 9#, and the specific preparation process is as follows:

According to the molar percentage of the 9# glass composition in the table, calculate the corresponding weight percentage of each composition, weigh each raw material and mix them uniformly; put the mixed material into a platinum crucible and melt it in a silicon carbide rod electric furnace at 940 ° C, and melt it completely After clarifying for 25 minutes, pour the molten glass on the mold preheated at 320°C; quickly move the glass into a muffle furnace that has been heated to 340°C for annealing, keep it warm for 6 hours, and then cool it down to room temperature at a rate of 10°C/hour , and the glass sample was taken out after complete cooling to obtain a rare earth doped fluoride glass.

Embodiment 10#:

The raw material composition is as shown in Table 10#, and the specific preparation process is as follows:

According to the molar percentage of the 10# glass composition in the table, calculate the corresponding weight percentage of each composition, weigh each raw material and mix them evenly; put the mixed material into a platinum crucible and melt it in a silicon carbide rod electric furnace at 950 °C until completely melted After clarifying for 25 minutes, pour the molten glass on the mold preheated at 320°C; quickly move the glass into a muffle furnace that has been heated to 340°C for annealing, keep it warm for 6 hours, and then cool it down to room temperature at a rate of 10°C/hour , and the glass sample was taken out after complete cooling to obtain a rare earth doped fluoride glass.

Embodiment 11#:

The raw material composition is as shown in Table 11#, and the specific preparation process is as follows:

According to the mole percentage of the 11# glass composition in the table, calculate the corresponding weight percentage of each composition, weigh each raw material and mix them evenly; put the mixture into a platinum crucible and melt it in a silicon carbide rod electric furnace at 960°C until completely melted After clarifying for 25 minutes, pour the molten glass on the mold preheated at 320°C; quickly move the glass into a muffle furnace that has been heated to 340°C for annealing, keep it warm for 6 hours, and then cool it down to room temperature at a rate of 10°C/hour , and the glass sample was taken out after complete cooling to obtain a rare earth doped fluoride glass.

Embodiment 12#:

The raw material composition is as shown in Table 12#, and the specific preparation process is as follows:

According to the mole percentage of the 12# glass composition in the table, calculate the corresponding weight percentage of each composition, weigh each raw material and mix them evenly; put the mixture into a platinum crucible and melt it in a silicon carbide rod electric furnace at 960°C until completely melted After clarifying for 25 minutes, pour the molten glass on the mold preheated at 330°C; quickly move the glass into a muffle furnace that has been heated to 340°C for annealing, keep it warm for 6 hours, and then lower it to room temperature at a rate of 10°C/hour , and the glass sample was taken out after complete cooling to obtain a rare earth doped fluoride glass.

Claims (2)

1. A rare earth-doped fluoride glass for white light LED, characterized in that the structural formula of the glass is as follows: (50-x)ZrF ₄ -xZnF ₂ -33BaF ₂ -10YF ₃ -7AlF ₃ :yRe ³⁺ Wherein, the value range of x is 0-20, the value range of y is 0.2-4, and Re is co-doped with Pr ³⁺ and Ho ³⁺ . 2. The preparation method of rare earth-doped fluoride glass according to claim 1, characterized in that the method comprises the following steps: ① Select the composition of Re and the values of x and y according to the structural formula of the rare earth-doped fluoride glass, calculate the weight of each corresponding glass composition, and accurately weigh each raw material. The ZrF ₄ is composed of H ₈ F ₆ N ₂ Zr is introduced, other components are introduced by ZnF ₂ , BaF ₂ , YF ₃ , AlF ₃ , rare earth ions are introduced by PrF ₃ , HoF ₃ , and the purity of raw materials is 99.9%; ② Grind the weighed raw materials in a mortar and mix them evenly to form a mixture; ③ Put the mixed material into a platinum crucible and melt it in a silicon carbon rod electric furnace at 900-960° C., keep it warm for 10-20 minutes to obtain molten glass, and clarify the molten glass for 10-25 minutes; ④Take out the platinum crucible, and pour the clarified glass liquid on the stainless steel mold preheated to 300-330°C to obtain colorless and transparent glass; ⑤ Move the colorless and transparent glass into a muffle furnace that has been heated to 10°C-25°C lower than the transition temperature for annealing treatment, keep it warm for 4-8 hours, and then lower it at a rate of 10-25°C/hour. to room temperature to obtain rare earth doped fluoride glass.