Long-lasting glow materials referred to long afterglow materials, also known as the luminescent material, luminous material, which is essentially a photoluminescent material.
Long-lasting glow materials referred to afterglow materials, also known as the luminescent material, which is essentially a photoluminescent material, he is a kind of absorbed energy as visible light, ultraviolet, X-ray, etc., and The substance can continue to emit light after excitation stop, he can be able to trap the energy stored in the material, is a kind of promising.
Long afterglow is one of the earliest materials research and application, many natural ore itself has long afterglow emission characteristics, and for the production of items such as “Moonwalker”, “Night Pearl”, etc. (Figure 1). Real written records might be in our Taizong during the Song Dynasty (AD 976–997 years) described (FIG. 2) with a “long-lasting paint” draw “cow painting”, painting the cow into the night’ll see that the reason is that this painting cow is made of photoluminescent pigment painted with oysters, Western earliest record of such light-emitting material in 1603 when an Italian cobbler local ore roasting alchemists, got some in the dark the red light material, after analysis showed that, within the ore containing barium sulfate, after reduction roasting became a part of barium sulfide long-lasting material. Since then, the 1764 British and sulfur mixed with oyster fired a blue-white light-emitting materials, namely calcium sulfide long afterglow.
Since 1993, the co-doped synthetic Matsuzawa Dy of SrAl2O4: Eu study found that the afterglow decay time of up to 2000min. Subsequently, it has successively developed a series of rare earth activated aluminate long afterglow materials, such as blue CaA12O4: Eu, Nd and cyan Sr4Al14O25: Eu, Dy, its long-lasting materials and afterglow performance parameters in Table 1. Aluminate long-lasting material, which is mainly the activator Eu, afterglow luminescent color mainly in blue-green wavelength range. Today, although the water was not very good aluminate, aluminate long afterglow material SrA12O4: Eu, Dy and Sr4Al14O25: Eu, Dy still get a great commercial application is the main stage of long-lasting material Follow materials research and applications.
Silicate matrix using long-lasting materials, due to the silicate has excellent chemical stability and thermal stability, while raw material SiO2 cheap, easy to get, in recent years more and more people’s attention, and this silicates material widely used in lighting and display areas. Since 1975 Japan first developed a long-lasting material silicate Zn2SiO4: Mn, As, its afterglow time was 30min.
Since then, a variety of silicate long-lasting materials have also been developed, such as Sr2MgSi2O7: Eu, Dy, Ca2MgSi2O7: Eu, Dy, MgSiO3: Mn, Eu, Dy, material and performance parameters in Table 1. Silicate matrix long-lasting material for the main activator Eu2 +, its luminous colors still concentrated in blue-green, although there are reports of red silicate long-lasting material. Afterglow better performance is co-doped Eu and Dy Sr2MgSi2O7 and Ca2MgSi2O7, its afterglow duration longer than 20h. In addition, observed in Mn, Eu, Dy co-doped MgSiO3 three elements into a red long-lasting phenomenon. Silicate aluminate long-lasting material has incomparable advantages in terms of water resistance, but its poor performance than aluminate.
In addition to the above-mentioned categories of long-lasting materials, research materials as well as more long-lasting sulfide ZnS: Cu, Co and CaS: Eu, Tm represented, which is characterized by the color variety, but the maximum initial afterglow luminance only 40mcd / m or so, and this type of material in the first few minutes, the afterglow of a sharp decline in effective afterglow time is very short. There Pr doped titanate CaTiO3: Pr, Al. Up to now, the long-lasting luminescence in the oxidation system has been extensively studied, it is worth noting that chlorine oxide Ca8Zn (SiO4) 4Cl2: Eu, the nitride-containing Ca2Si5N8: Eu is also a long-lasting phenomenon.
In addition, Professor Pan Zhengwei research group has developed a long near-infrared long-lasting material Zn3Ga2Ge2O10: Cr, its afterglow time up to 360h