Excitation-wavelength-depended Colorful Fluorescence In Rare-Earth Doped Yttrium-aluminum-silicate Glasses

Under UV excitation, rare-earth (RE) doped optical glasses produce efficiently visibleemissions due to the especial energy level structure of RE ions, such material has broadapplication in the visible display areas and many researchers are focusing on that point.Furthermore, because the warm colors make eyes feel comfortable, more and more attentionshave been paid to the warmly colorful fluorescence and white light. Currently, the type of“blue LED+Yellow phosphors” is widely used in the commercial white optical device. Ce3+doped YAG phosphors emit yellow fluorescence under blue light excitation and the whiteluminescence has been generated by mixture of yellow and blue. But this white light is lack ofred and uncomfortable to the human’s eye, moreover single excitation wavelength andcorrelated color temperature (higher than6000K) are not benefit to the wide application inhigh-quality lighting.Based on above, rare-earth (Eu2+/Eu3+, Tb3+and Eu2+/Eu3+/Tb3+) dopedlithium-yttrium-aluminum-silicate (LYAS) glasses, attributing to the simultaneous generationof three primary color emits from Eu3+(red), Eu2+(blue), and Tb3+(green) by varying the UVradiation wavelength, have been synthesized. By investigating the fluorescence characteristicsof the sample, the colorful fluorescent color coordinates and color temperatures have beenobtained, and the movement of color coordinates has been exposed in the1931-CIE picture.This RE doped LYAS glasses laid the foundation for high-quality lighting in Whitefluorescent devices, and the followings are results this work achieved:1. Eu2+/Eu3+, Tb3+and Eu2+/Eu3+/Tb3+doped LYAS glasses have been synthesized andcharacterized, red (Eu2+), blue-violet (Eu3+) and green (Tb3+) fluorescence have been observedunder UV excitation. In Eu2O3doped sample, Dynamic and colorful fluorescence has beenachieved by cooperation between Eu2+and Eu3+, relative spectral power distribution underdifferent excitation wavelength have been calculated via correction curve which correct theimpact of non-uniform response in photomultiplier tube. Then, color coordinates have beenmarked in the1931-CIE picture, and the trend of movement indicates the characteristics of this wavelength-dependent optical materials. Under360nm excitation, the Fluorescence closeto the white point, and color coordinates is (0.347,0.268), color temperature is4357K.2. The fluorescence component of Eu2O3doped LYAS glasses have been optimized byintroducing Tb3+which generate green emission under UV light. Compared with Eu2+/Eu3+doped LYAS glasses, the color coordinates of Eu2+/Eu3+/Tb3+doped LYAS glasses were moveto green area, and located in white area. Furthermore, the long-wavelength UV can active theEu2+/Eu3+/Tb3+ions at same time by analyzing the excitation spectrum which monitors thecharacteristic wavelength of Eu2+/Eu3+/Tb3+. And then the calculated color coordinates in1931-the CIE diagram, indicate the excellent florescence trajectory and reveal thecharacteristics of this wavelength dependent optical materials.360nm excitation fluorescenceclose to the white point with CIE coordinates of (0.338,0.298), color temperature5146K.