Classification and characteristics of different glow powders(1)

There are mainly 3 categories of phosphors for lamps. The first category is used for ordinary fluorescent lamps and low-pressure mercury lamps, the second category is used for high-pressure mercury lamps and self-ballasted fluorescent lamps, and the third category is used for ultraviolet light sources, etc. There are many types of phosphors, and the price is different, phosphors have good thermal stability, safety and environmental protection, for a variety of white light, can be adjusted to different red, blue, yellow and so on the color.

1. Fluorescent lamps and low-pressure mercury lamps with phosphors

There are antimony, manganese activated calcium halophosphate phosphor and rare earth trichromatic phosphor.

Antimony, manganese activated calcium phosphate phosphor is in the fluorine chlorapatite matrix 3Ca3 (PO4) 2-Ca (F, Cl) 2 mixed with a small amount of activator antimony (Sb) and manganese (Mn) made after the phosphor, usually expressed as

3Ca3(PO4)2-Ca(F,Cl)2:Sb,Mn

This phosphor preparation method can be used in many different raw materials, but the purity of the raw materials required high. Preparation of the mix, the amount of raw materials first from the apatite structure for theoretical calculations in the calcium halophosphate, the sum of the gram atomic and manganese to phosphate in the gram atomic ratio of 4.9:3; then weighing, mixing, grinding, sieving and then in a certain atmosphere (generally with nitrogen), sintered at a constant temperature of about 1150 ° C for a few hours; removed and cooled, selected under the ultraviolet lamp, and then finely ground Sieving is the finished product.

When the activator Sb absorbs the excitation energy will be part of the energy released in the form of light radiation, the use of the above phenomenon just change the content of Mn, you can get different color temperature of calcium halophosphate phosphor.

The ability of the phosphor to absorb radiation is related to the degree of phosphor dispersion, so the size of its particle size has a great impact on the glow brightness. Calcium halophosphate phosphor particle size is determined by the size of the raw material CaHPO4, therefore, to obtain a certain size and lattice of crystal CaHPO4, you can control the phosphor particle size in a certain size (5 ~ 10µ), so as to obtain high glow brightness.

Rare-earth trichromatic phosphor, red powder for europium-activated yttrium oxide (Y2O3: Eu), green powder for cerium, terbium-activated aluminate (MgAl11O19: Ce, Tb), blue powder for low-valent europium-activated barium magnesium aluminate (BaMg2Al16O27: Eu). 3 kinds of powder mixed in a certain proportion can get different color temperature (2700 ~ 6500K), the corresponding lamp glow In general, the higher the content of green powder, the lower the content of blue powder, the higher the glow efficiency of the lamp. In addition, the blue powder increases, the color temperature increases; red powder increases, the color temperature decreases.

Three kinds of base color powder substrate and activation substances are different, but the key to luminescence are rare earth activation substances (europium, cerium, terbium, etc.), the use of rare earth metal outer ion (D → F) leap and luminescence.

The use of rare-earth trichromatic phosphor trichromatic fluorescent lamp itself has many outstanding advantages, however, rare-earth raw materials are expensive, resulting in the higher cost of trichromatic lamps, limiting the development of trichromatic lamps. Reduce the diameter of the tube or the use of new coating technology to reduce the amount of trichromatic powder, with inexpensive other color powder to partially replace one or two rare earth trichromatic powder, the same can be made of high glow efficiency, high color rendering fluorescent lamps, but the light failure may be a little larger.