Luminescence Property of Eu3+-doped CaZrSi2O7 Phosphors for White LEDs

Abstract

Eu3+-doped CaZrSi2O7 phosphors with promising luminescent properties have been successfully prepared through microwave heating. The crystallinity and luminescent performance were characterized by powder X-ray diffraction pattern, photoluminescence spectra, respectively. The results show that the obtained Eu3+-doped CaZrSi2O7 phosphors have good crystallinity, and strong emission under near-ultraviolet ( NUV) light excitation, which emits red colors peaking at 615 nm, corresponding to the 5D0→7F2 electric-dipole transition of Eu3+ which shows the rare earth Eu3+ ions are located in noncentrosymmetric sites. The red emission of Eu3+-doped CaZrSi2O7 phosphors is excellently consistent with CIE chromaticity standards. It is suggested that the as-prepared Eu3+-doped CaZrSi2O7 samples have high potential for phosphor-converted white LEDs application. Introduction In recent years ,white light emitting diodes (W-LEDs) which are regarded as a new solid state light soures have been widely used in many fields such as displays and lighting because of its many merits of high compact size, low energy consumption, higher luminous efficiency, environmental friendliness and longer lifetime[1,2]. Although the efficiency of commercially white LEDs which were usually prepared through combining blue LED chip with yellow Y3Al5O12:Ce3+ phosphors is high, the color rending index is relatively low due to a lack of sufficient red component[3]. To overcome these problems, phosphor-converted white LEDs have been paid special attention to as it provides high CRI. The availabile commercially phosphors for near UV excited LEDs are mostly red Y2O2S:Eu3+, green ZnS:Cu+,Al3+ and blue BaMgAl10O7:Eu2+. However, Y2O2S:Eu3+ and ZnS:Cu+,Al3+ phosphors were instability (releasing of sulfide gas) under UV irradiation and result in low quantum efficiency. In the case, recently a lot of researchers have made extensive efforts to search for new phosphor for white LEDs aplication and through effectively combining red, green and blue emitting phosphors togather to enhance color rending index [4-6]. Nowadays,silicates have attracted much attention to be applied to luminescent materials due to its advantages of outstanding chemical stability and optical performance[7,8]. Moreover, rare earth ion doped silicates phosphors have been widely investigated due to its excellent application in white light emitting diodes [9-11]. Furthmore, a lot of advantages have been found through microwave-induced method to prepared solid oxide materials compared to the conventional synthesis mehtod in terms of its heating mode [12-13 ], which microwave can heat the material at the molecular level, so that the heating is uniform. In addition, in the preparing process by microwave-induced method, the reaction time is not long and it is not needed to apply expensive instrument, which makes the technology attractive. In the work, by using improving microwave heating prepare process, a pure phase Eu3+-doped CaZrSi2O7 (abbrev:CZSO) phosphor for white light emitting diodes application have been International Conference on Modeling, Analysis, Simulation Technologies and Applications (MASTA 2019) Copyright © 2019, the Authors. Published by Atlantis Press. This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/). Advances in Intelligent Systems Research, volume 168