Tungstate Red Phosphor

White LED is a new solid-state lighting electric light source (SSL). Its principle and structure are different from those of previous vacuum electric light sources such as incandescent lamp and fluorescent lamp. SSL light source has many advantages, especially high light efficiency, energy saving, long life and pollution-free. It has great application value and prospects.

There are many kinds of tungstate in the form of M W O. The existing tungstate is Eu³⁺ doped Mx (WO₄)_y (Gd2 (WO₄)₃), Mx (WO₆) (such as), and so on. However, the amount of tungsten element used in the preparation of the above materials is large. Because tungsten is a more expensive material, the high temperature solid phase method for preparing tungstate phosphors has high energy consumption and sol-gel and hydrothermal. The cost of tungstate is high due to the time-consuming synthesis methods, which is unfavorable for reducing the cost of phosphors. Therefore, finding a more economical and convenient synthesis method of tungstate materials is one of the focuses of current research.

Some scholars used the following steps to prepare tungstate red phosphors excited by near ultraviolet or blue light:

1. 0.336g analytical pure LaCl₃·6H₂O and 0.018g analytical pure EuCl₃·6H₂O were weighed and dissolved in 20 mL deionized water to obtain rare earth solution.

2. 0.165g analytical pure Na₂WO₄ ·2H₂O was dissolved in 50 mL deionized water, and then the pH value of the solution was adjusted by ammonia water to get Na₂WO₄ solution.

3.Under stirring conditions, the rare earth solution prepared in step 1 is dripped into the Na₂WO₄ solution prepared in step 2. After all the rare earth solution is dripped into the solution, the white suspension is stirred for 30 minutes to complete the reaction, filter and obtain the precipitate.

4.Wash the sediment obtained by step 3 with deionized water, then centrifuge the sediment out of the water and dry it in a drying box at 200 ℃ for 1 hour.

5.The precipitate treated by step 4 is put into muffle furnace, sintered at 800 ℃ for 2 hours, then cooled and ground to obtain tungstate red phosphors excited by near ultraviolet or blue light.

The prepared tungstate red phosphor has a luminescence intensity of nearly 2 to 12 times that of the Y2O2S:Eu commercial powder under the excitation of near ultraviolet light and blue light, and has the same luminescence properties as other types of tungstate phosphor materials. And in the case of the same luminous center (Eu) capacity, the amount of W is the least, and the synthesis cycle takes only 2-7 hours, and the cost is the lowest. It can be used in GaN-based blue light-emitting diodes with the red-light component of YAG:Ce phosphor white LED system, and can also be used as the red phosphor of the three-primary white LED of the near-ultraviolet chip.

• < Prev
• Next >