a Key Laboratory of Luminescence and Optical Information, Beijing Jiaotong University, Ministry of Education, Beijing 100044, China; b Institute of Optoelectronics Technology, Beijing Jiaotong University, Beijing 100044, China
Abstract In this work, a simple method to modulate the crystal phase and morphology with a large amount of K+ ions codoping is proposed. The phase changes to the mixture of β-NaYF4 and β -KYF4 with increasing the content of K+ ions to 80 mol%. When it exceeds 80 mol%, β -NaYF4 disappears gradually and β -KYF4 dominates with a poor crystalline. In addition, the morphology changes from nanosphere to nanoplate, and then to nanoprism, which indicates that a higher content of K+ ions favors the growth rates along [0001] than the [10-10] of the nanocrystals. Additionally, the upconversion (UC) luminescence properties and the ratio of red/green (R/G) UC intensity of samples with different phases and morphologies are detected, which makes it possible to tune the UC fluorescence by varying the concentration of K+ ions.
Fund: Project supported by the National High Technology Research and Development Program of China (Grant No. 2013AA032205), the National Natural Science Foundation of China (Grant No. 51272022), and the Fundamental Research Funds for the Central Universities, China (Grant No. 2012JBZ001).
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