Photoluminescence properties of Ca0.99Eu0.01(Mo1−xSix)O4 nanocrystals red-phosphors obtained by the hydrothermal method

Abstract

Abstract In this paper, we report the obtention of a novel red-emitting Ca 0.99 Eu 0.01 (Mo 1− x Si x )O 4 nanocrystals phosphor synthesized by the hydrothermal method for the first time, and its photoluminescence (PL) properties were investigated for application to white-light-emitting diodes (W-LEDs). The as-synthesized phosphors were characterized by means of X-ray powder diffraction (XRD), transmission electron microscope (TEM), high-resolution transmission electron microcopy (HR-TEM), photoluminescence excitation (PLE) and PL emission spectra. XRD patterns, TEM images and PL emission indicated that the introduction of Si 4+ ions promotes the distortion and slight shrinking of the unit cell, narrow size distribution and the blue-shift of the charge transfer bands of Ca 0.99 Eu 0.01 MoO 4 red-phosphors. PL properties revealed that the optical brightness as well as the intensity ratio of 5 D 0 → 7 F 2 to 5 D 0 → 7 F 1 was highly dependent on the Si 4+ ions concentration. The morphological evolution was explained via a crystal growth mechanism. Introduction of 5 mol% Si 4+ ions into the crystal structure enhanced the PL emission brightness, and the nanocrystals Ca 0.99 Eu 0.01 (Mo 0.95 Si 0.05 )O 4 red-phosphors showed the relatively most promising PL performance with the most intense emission. The CIE chromaticity coordinates for nanocrystals Ca 0.99 Eu 0.01 (Mo 1− x Si x )O 4 red-phosphors were simulated and located in the red region. All the results imply that the studied Ca 0.99 Eu 0.01 (Mo 1− x Si x )O 4 nanophosphors could be potentially used as W-LEDs.