One-step preparation of Ca-α-SiAlON:Eu2+ fine powder phosphors for white light-emitting diodes

Abstract

A simple methodology for producing yellow-emitting Ca-α-SiAlON:Eu2+ phosphors for white light-emitting diodes has been developed, which consists of postsynthesis activation of fine α-SiAlON powders prepared by the gas-reduction-nitridation method. Phase-pure, fine Ca-α-SiAlON:Eu2+ phosphors possessing the particle size ranging ∼0.9–2.8μm and high quantum efficiencies of ∼44%–55% under near-UV to blue light excitation are obtained as the process developed. The chromaticity coordinate of the synthesized Ca-α-SiAlON:Eu2+ can be tailored by simply controlling the activator concentration, enabling the creation of a broad range of warm-white light with the correlated color temperatures of ∼3500–2600K.

Dopant Concentration Induced Optical Changes in Ca,Eu-α-Sialon

“…The emission peak position shifts toward longer wavelengths with rising Eu 2+ concentration from 565 nm (0.1 mol % Eu 2+ ) to 585 nm (10 mol % Eu 2+ ) and its intensity changes in the same manner as for PLE spectra. This optical characterization was reported earlier for Ca,Eu-α-sialon phosphor with similar composition [6,7,[14][15][16][17][18]23,[33][34][35][36][37][38][39][40]43]. Moreover, as it is discussed below, there is no clear relationship between AlN content and optical properties e.g.…”

“…The optical properties of selected α-sialon:Eu 2+ samples with respect to temperatures in the range of 10 to 500 K and pressures up to 240 kbar are presented. It is well known [18,25,[38][39][40][41][42][43] that by changing the composition of α-sialon (which means changing the degree of substitution of Si-N by Al-O bonds and thus changing the environment around the Eu 2+ ions) it is possible to tune, in a certain range, the luminescence properties of Eu 2+ doped α-sialon phosphors. The main effect of high pressure is compression of the crystal, i.e., a decrease in its volume and as a consequence a decrease in interatomic distances.…”

Photoluminescence properties of Sr1–xSi2O2N2: Eu2+x as green to yellow-emitting phosphor for blue pumped white LEDs

“…Recently, the inorganic materials that can be applied to white light emitting diodes (WLEDs) have attracted considerable attention on account of their high brightness, long lifetime and lower power consumption than traditional fluorescence and incandescent lamps [1][2][3]. Currently, WLEDs are made from a combination of an InGaN blue chip with yttrium aluminum garnet-doped Ce 3 + (YAG: Ce 3 + ) yellow phosphors [4].…”

Efficiency Enhancement of Bredigite‐Structure Ca14Mg2[SiO4]8:Eu2+ Phosphor via Partial Nitridation for Solid‐State Lighting Applications

“…Nowadays, new light‐emitting diode (LED) phosphors, including oxide, oxyfluoride, nitride, and oxynitride host lattices were used in conjunction with near‐UV and blue light sources. These phosphors have attracted a lot of attention because the eventual performance of white‐LED‐based devices strongly depends on the luminescence properties of the phosphors used.…”