Article pubs.acs.org/IC
A Potential Red-Emitting Phosphor BaZrGe3O9:Eu3+ for WLED and FED Applications: Synthesis, Structure, and Luminescence Properties Qiang Zhang, Xicheng Wang, Xin Ding, and Yuhua Wang* Key Laborary of Special Function Materials and Structure Design, Ministry of Education, Department of Materials Science, School of Physical Science and Technology, National & local Joint Engineering Laboratory for Optical Conversion Materials and Technology, Lanzhou University, Tianshui South Road No. 222, Lanzhou, Gansu 730000, P. R. China ABSTRACT: A variety of Eu3+-activated BaZrGe3O9 phosphors was synthesized via solid-state reaction. The phase formation of BaZrGe3O9:Eu3+ samples was verified by powder X-ray diffraction analysis, while Rietveld refinement method was used to confirm the crystal structure. The electronic structure and characteristic photoluminescence as well as cathodoluminescence properties were researched in detail. The samples show strong absorption at 394 nm, which matches well with the commercial near-ultraviolet chips. Under 394 nm excitation, the phosphors exhibit the characteristic emissions of Eu3+ ions consistent with the 5D0−7FJ transitions. Then we investigated the thermal stability detailedly. The temperature-dependent photoluminescence emission spectra suggest that the obtained phosphors have favorable thermal stability. A white light-emitting diode (WLED) lamp with low correlated color temperature and good color render index was fabricated with blue-emitting BaMgAl10O17:Eu2+, green-emitting Sr2SiO4:Eu2+ (commercial), and red-emitting BaZrGe3O9:Eu3+ phosphors in near-ultraviolet light-emitting diodes (λmax = 395 nm) as well. Furthermore, the phosphor also exhibits red emission with high resistance and high current saturation under low voltage electron bombardment. It has better degradation resistance than the commercial Y2O3:Eu phosphor. All the results manifest that the Ba0.88Eu0.08ZrGe3O9 phosphor can be an eligible red-emitting phosphor candidate for WLEDs and field-emission displays.
1. INTRODUCTION As the next promising generation light source, white lightemitting diodes (WLEDs) possess several superior properties, such as high brightness, long operation time, and environment friendliness. It is expected that WLEDs will take the place of the traditional fluorescent lamps in the near future.1 A typical WLED was devised by combining the blue InGaN chip with a yellow-emitting Y3Al5O12:Ce3+ phosphor. Yet, it has some drawbacks, including high correlated color temperature (CCT; 4000−8000 K) and poor color rendering index (Ra usually
