Luminescent properties of Eu³⁺-doped α-NaYF₄ single crystal under NUV-excitation

Abstract

This paper reports on successful synthesis of α-NaYF₄ single crystal doped with Eu³⁺ at various concentrations by a modified Bridgman method. The crystal structure is characterized by means of X-ray diffraction. The absorption spectra, excitation spectra and emission spectra were measured to investigate the optical properties of the single crystals. An intense red emission located at 611 nm with long lifetime of 9.03 ms was observed in single crystal under the excitation of 394 nm light. It benefits from the low maximum phonon energy of α-NaYF₄ single crystal matrix (390 cm⁻¹). The CIE chromaticity coordinate of the α-NaYF₄ single crystal doped Eu³⁺ in 4 mol% concentration was calculated (x = 0.6055, y = 0.388), which was close to the National Television Standard Committee standard values for red phosphor (x = 0.67, y = 0.33). All these spectral properties suggest that that this kind of fluoride crystal with high thermal stability and high efficiency of red emission may be used as potential red phosphors for optical devices.

Keywords:

• Eu³⁺ ion
• single crystal
• red phosphors
• near ultraviolet excitation
• decay lifetimes