introduction In 1962, Holonyak et al. used GaAsP to prepare the first red-emitting LED. After more than 30 years of development, the LED's luminous efficiency has been greatly improved, and the emission wavelength range has been expanded to the green, yellow and blue regions. In 1993, Nakamura.S and others took the lead in making breakthroughs in blue gallium nitride (GaN) LED technology. In 1996, Y3Al5O12:Ce3+ (YAG:Ce3+), which emits yellow light, was used as a phosphor to be coated on a blue-emitting GaN diode. Successfully prepared white LEDs. White light LEDs have received extensive attention as soon as they appear. The lighting as a light source is characterized by environmental protection, energy saving, high efficiency, long life and easy maintenance. It is called to surpass incandescent lamps, fluorescent lamps and high-intensity discharge lamps (HID). The fourth generation of lighting sources is the first choice for today's society pursuing a low carbon economy [1, 2]. At present, the realization of white LED is mainly to use a combination of LED chip and phosphor, and the short-wavelength light emitted by the chip is partially or completely converted into visible light by a phosphor, and finally combined into white light. The focus is on the research, development and production of phosphors for light color conversion. The most researched and most mature is the blue LED/yellow phosphor system. The phosphor used in this system is Y3Al5-O12:Ce3+ and phosphor based on Y3Al5O12:Ce3+. However, the phosphor has a low luminous efficiency; in addition, at high currents, the electro-optic intensity of the blue spectrum is increased faster than the yellow light, and the change in current causes a mismatch in the spectrum, which tends to cause a change in color temperature. And a low color rendering index. However, the ultraviolet and near-ultraviolet systems do not exist. Because of the low electrical conversion efficiency of the UV-converting phosphor system, it is of great significance to study near-ultraviolet-converting phosphors [3]. 1 Characteristics of phosphors for single-substrate white LEDs The near-ultraviolet-converting phosphor can be classified into a single-substrate white phosphor and a plurality of matrix white phosphors. The single-substrate white phosphor can directly emit white light under the excitation of near-ultraviolet light. Compared with other system phosphors, it has remarkable characteristics: (1) due to the insensitivity of vision to near-ultraviolet light, such white LEDs The color is determined by the phosphor, so the color is stable, the color reproduction is high; (2) because it is a single matrix compound, it can reduce the energy loss and help to improve the luminous efficiency; (3) avoid the interaction between multiple matrix compounds. The resulting color misalignment is conducive to improving color rendering; (4) cost reduction. Therefore, single-substrate white-light phosphors have attracted more and more attention in recent years, and have become a research hotspot of a new generation of white-light LED lighting. Research on this system material has gradually deepened. 2 Research status of phosphors for single-substrate white LEDs In recent years, studies on single-substrate white phosphors have been reported in a large number of literatures, covering a wide range of matrix compounds, including silicates, phosphates, borates, vanadates, aluminates, and the like. The activated ions are mainly Eu2+ and Ce3+, because their electronic configuration is exposed to the outer layer of d electrons, which is susceptible to the matrix lattice environment and chemical bond properties. The f→d transition absorption band and the d→f transition emission band are easily broadened. In addition to Eu2+ and Ce3+, Mn2+, Eu3+, Dy3+, Tb3+, etc. are also often used as activating ions in a single matrix white fluorescent system. The most common one is a single-substrate white phosphor that is co-doped with two ions, such as Eu2+-Mn2+, Ce3+-Mn2+, and the like. 2.1 silicate phosphor The silicate system has some outstanding characteristics, such as long-term bombardment by UV photons, stable performance, high light conversion efficiency, excellent crystallinity and light transmission performance, wide spectrum excitation band, and continuous adjustable emission spectrum. Therefore, silicate phosphors are considered to be a promising phosphor material [4]. Kim et al [5-9] synthesized a series of M3MgSi2O8:Eu2+, Mn2+ (M=Ba, Sr, Ca) phosphors. In this system, M has three kinds of positions, 12-coordinated M(I) and 10-coordinated M(II, III). Eu2+ emits blue light when it replaces the M(I) position, emits green light when it replaces the M(II,III) position, and emits red light when Mn2+ replaces the M(I,II,III) position. When M=Ba, under the excitation of 375nm near-ultraviolet LED, the phosphor simultaneously emits blue, green and red light colors of 440nm, 505nm and 620nm, and is combined with ultraviolet LED to form white light with color coordinates (0.38, 0.35). Figure 1 is a graph showing the excitation spectrum and emission spectrum of Ba3MgSi2O8:Eu2+, Mn2+. When M = Sr, the excitation spectrum broadens at 400 nm and the emission is red shifted. By adjusting the concentration of Eu2+ and Mn2+, the color temperature and color rendering index of the emitted light can be changed. The optimal color temperature is 3600K, the color rendering index is 95, and the color code is stable to current, which is far superior to the luminescence of YAG:Ce3+-InGaN system. . When M = Ca, the emission peak continues to red shift, mainly because the ionic radius becomes smaller, causing the crystal field to change, causing the emission peak to be red-shifted. The incorporation of a small amount of Al ions causes a significant change in the relative intensities of the blue and green light of the phosphor, while the intensity of the red light is substantially constant, so the color coordinate position of the phosphor can be regulated by incorporating different amounts of aluminum ions [10] ].