RESEARCH PAPER Hydrothermal synthesis, characterization, and luminescence of Ca 2 B 2 O 5 :RE (RE 5 Eu 3+ , Tb 3+ , Dy 3+ ) nanofibers Li Yang . Yingpeng Wan . Yuze Li . Yinfu Pu . Yanlin Huang . Cuili Chen . Hyo Jin Seo Received: 29 July 2015 / Accepted: 17 February 2016 Ó Springer Science+Business Media Dordrecht 2016 Abstract Ca 2 B 2 O 5 :RE (RE = Eu 3? , Tb 3? , Dy 3? ) nanofibers were synthesized by the hydrothermal reaction method. The structural refinement was con- ducted on the base of the X-ray powder diffraction (XRD) measurements. The surface properties of the Ca 2 B 2 O 5 :RE (RE = Eu 3? , Tb 3? , Dy 3? ) nanofibers were investigated by the measurements such as the scanning electron microscope (SEM), transmission electron microscope (TEM), and the energy dispersive spectrum (EDS). The nanofiber has a diameter of about 100 nm and a length of several micrometers. The luminescence properties such as photolumines- cence excitation (PLE) and emission spectra (PL), decay lifetime, color coordinates, and the absolute internal quantum efficiency (QE) were reported. Ca 2 B 2 O 5 :Eu 3? nanofibers show the red luminescence with CIE coordinates of (x = 0.41, y = 0.51) and the luminescence lifetime of 0.63 ms. The luminescence of Ca 2 B 2 O 5 :Tb 3? nanofibers is green color (x = 0.29, y = 0.53) with the lifetime of 2.13 ms. However, Dy 3? -doped Ca 2 B 2 O 5 nanofibers present a single- phase white-color phosphor with the fluorescence decay of 3.05 ms. Upon near-UV excitation, the absolute quantum efficiency is measured to be 65, 35, and 37 % for Eu 3? -, Tb 3? -, Dy 3? -doped Ca 2 B 2 O 5 nanofibers, respectively. It is suggested that Ca 2 B 2- O 5 :RE (RE = Eu 3? , Tb 3? , Dy 3? ) nanofibers could be an efficient phosphor for lighting and display. Keywords Semiconductors Á Luminescence Á Nanocrystalline materials Á Optical materials and properties Introduction Borate family has versatile applications such as thermal, electrical, dielectric, optical, and catalytic materials due to the good mechanical performances, chemical stabilities, low prices, easy preparation, and considerable mineralogical and industrial importance (Haghiri et al. 2013; Wei et al. 2014). For example, calcium borates, including powders, ceramics, and nanoparticles, have been confirmed to be useful in the fields such as electrical and dialectical application, data storages, and lighting and display (Wan et al. 2014; Qi et al. 2014). Especially, the kind of these borates has a wide band gap and consequently is a good candidate to accommodate the rare earth (RE) activators. Accordingly RE-doped calcium borates are important luminescence materials, which have been L. Yang Á Y. Wan Á Y. Li Á Y. Pu Á Y. Huang (&) State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China e-mail: huang@suda.edu.cn C. Chen Á H. J. Seo (&) Department of Physics and Interdisciplinary Program of Biomedical Engineering, Pukyong National University, Busan 608-737, Republic of Korea e-mail: hjseo@pknu.ac.kr 123 J Nanopart Res (2016)18:94 DOI 10.1007/s11051-016-3372-7