American scientists developed a new material for warm white LED lamp

As everyone knows, LED (light emitting diode) lamp is high efficient and long service life, but because the current LED lamps to light blue luminescence light, which hindered the popularity of it in the field of indoor lighting.

Now, University of Georgia scientists have developed is said to be the world's first to use single phosphor and single light emitting unit warm white LED lamp. A paper on the details of the material is published in the latest issue of the journal Nature Science and applications.

Associate professor at the University of Georgia and lead author of the Pan Zhengwei (sound) said: "at present, the white LED lamp is mainly used in flash and car headlights, but they emit light blue light was not very welcoming love especially in the field of indoor lighting. Our materials have reached a warm color, but also to achieve a realistic color reduction. LED previously used single lamp phosphor improvement can not achieve this effect. "

Pan Zhengwei said that the measure of artificial light quality has two main indicators. Related color temperature is used to measure the temperature of light. For indoor lighting, color temperature is lower than 4000K (Kelvin temperature) is ideal, and the associated temperature is higher than 5000K, the light-emitting device will emit white light LED light blue light. Another important indicator is the color reduction, that is, the ability to simulate natural light source. Reduction of more than 80 is ideal for indoor lighting, the color is less than this value will appear distorted.

Pan Zhengwei and his colleagues developed materials to meet these two conditions, temperature was controlled at 4000K, while the color reduction degree has reached 85.

Pan Zhengwei said to the blue LED chip outer painted a different color fluorescent powder, can be a warm white, so that they can make white LED phosphor based on lamp. However, the proportion of these raw materials in accordance with the exact proportion of effort and money, and the resulting color difference will be different, because each kind of raw materials on the temperature changes are not the same.

Doctor of Engineering College of University of Georgia the author of the thesis, after reading Li Xufan (sound) said: "the use of a single color fluorescent powder can solve the instability problem, because a single material does not change with the increase of temperature. "

In order to develop a new fluorescent powder, Pan Zhengwei and his team selected europium oxide, aluminum oxide, barium oxide and graphite powder, each take a small amount of mixed together. Then they put the powder into a tube furnace and heat it to 1450 degrees celsius. The vacuum state in the furnace causes the vaporized material to fall onto the chassis, which is deposited as a yellow emitting compound, and then loaded into the bulb.

The results research is promising, but Pan Zhengwei stressed that need to solve several problems to be this material for families, businesses and schools lighting. The light effect of the new material is much lower than the current light blue white LED lamp. In addition, large-scale production will also face challenges.