| Semiconductor lighting (Lighting Emitting Diode:LED) has been widely used in our daily lives, and the phosphors are key materials. The white LED mainly combined by blue light of semiconductor chips and yellow light of YAG:Ce phosphors. The white LED is different from sunlight. Sunlight contains ultraviolet radiation and a small amount of ultraviolet is helpful for our health. Therefore, phosphors emitting ultraviolet light may be applied to fabricate LED with health illumination function. In the present work, rare earth doped BaGd2ZnO5 phosphors have been investigated and ultraviolet radiation was realized by upconversion luminescence.Er3+ doped BaGd2ZnO5 powders were synthesized via the sol-gel method. Powder's XRD analysis showed that the synthesized BaGd2ZnO5:Er3+ phosphor is pure phase powder. It has orthorhombic structure with lattice constant of a=7.1624, b=12.50804 an c=5.77847. SEM showed the particle size distribution is about 20um but the powder has some agglomeration. Fluorescence spectroscopy showed that BaGd2ZnO5:Er3+ phosphor can emit 380nm UV-ultraviolet light under excitation of 480nm. Mixed with commercial YAG:Ce phosphor at a ratio of 1:9,2:8 and 3:7, BaGd2ZnO5:Er3+ phosphors were mounted onto commercial SMD LED chips to fabricate LED lamp. The electro-optical properties and UV intensity of LED luminescent lamp were measured using an integrating sphere instruments and UV light meter. With the increasing of the content of BaGd2ZnO5:Er3+ phosphor, the luminous flux of the mixed powder is decreasing, the color temperature increased slightly, Color-rendering index decreased slightly, and the luminous efficiency is reduced to some extent. Ultraviolet emissions are detected in all mixed powders. As a result, the composition was optimized as 20% BaGd2ZnO5:Er3+ in the commercial YAG phosphor by comprehensive evaluation of the LED lamp. |
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