Short communication Synthesis and photoluminescent properties of Sr (1x) Si 2 O 2 N 2 : xEu 2+ phosphor prepared by polymer metal complex method for WLEDs applications Dhia A. Hassan a,b , Jian Xu a , Yibin Chen a , Langkai Li a , Renjie Zeng a,c, * a Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005, PR China b Department of Chemistry, College of Education for Pure Science, University of Basrah, Basrah 61004, Iraq c Fujian Key Lab of Advanced Special Materials, Xiamen University, Xiamen 361005, PR China A R T I C L E I N F O Article history: Received 29 October 2015 Received in revised form 19 December 2015 Accepted 25 January 2016 Available online 28 January 2016 Keywords: A. Optical materials B. Sol–gel chemistry C. X-ray diffraction D. Luminescence D. Phosphors A B S T R A C T Green emitting Sr (1x) Si 2 O 2 N 2 : xEu 2+ (x = 0, 0.02, 0.04, 0.06, 0.08 and 0.1) phosphors were synthesized by polymer metal complex or pechini method. The XRD results confirm the formation of a pure phase at 1400  C for 3 h. The SEM and particles size results indicate that the prepared phosphor consists of a polyhedral crystalline shape with well dispersed and the average particle size around 6.5 mm. The maximum PL intensity was found at 0.04% Eu 2+ with a wide emission band between 460 and 640 nm and a green emission peak at 531.4 nm. The external quantum efficiency of 0.04% Eu 2+ sample was 43.13%. The results indicate that pechini method is an alternative way and close in efficiency to the solid state method to prepare SrSi 2 O 2 N 2 phosphor with higher homogeneity and more uniform size distribution for near UV and blue region applications for white light emitting diodes WLEDs. ã 2016 Published by Elsevier Ltd. 1. Introduction White light emitting diodes (WLEDs) have been investigated extensively in the applications of solid state lighting such as backlighting source for liquid crystal displays, incandescent lamps and indicators due to their low operating voltage, reducing energy consumption, increasing the emission efficiency and long opera- tion life time. It is expected to replace the conventional incandescent lamps to be considered the next generation of the lighting system [1,2]. SrSi 2 O 2 N 2 (SSON) is an excellent oxynitride host material as wavelength conversion phosphors in the WLEDs applications due to its high quantum efficiency, strong absorption in the near UV to blue-light region, good thermal and chemical stability compared to most oxide and sulfide phosphors [3]. The luminescent properties of Eu 2+ doped SSON prepared by conventional solid state reaction have been thoroughly studied [3,4]. The results revealed poor homogeneity particles and need a high sintering temperature, therefore many alternative methods are used to obviate these problems such as, sol–gel [5], hydrothermal reaction [6], microwave reaction [3] and carbother- mal reduction [7]. The chemical methods play important roles in the processing of phosphor, due to the high purity and composi- tional homogeneity of the produced powder with a low tempera- ture synthesis [8,9]. Polymer metal complex or pechini method (PM) is a polymer sol–gel process suitable to produce an oxide network from molecular precursors by polymerization reaction with stable citrate/metal complexes formed [8] and well ions dispersed in the polymer network at the molecular level without precipitation; yields finer powders with a more uniform size distribution, as well as high purity, short heating time, low cost, low temperature process and its simplicity. Many researches have been conducted to prepare SrSi 2 O 2 N 2 : Eu 2+ in a homogenous form with a small particle size, since the particle size, shape and morphology have a significant effect on photoluminescence properties of phosphors [10], The morphology of SSO was found non-uniform and have agglomeration [11,12]. Despite the difficulties to obtain nitride phosphor by PM [13]; we successfully investigated a suitable procedure by DTA–TG curves to prepare SrSi 2 O 2 N 2 : Eu 2+ phosphor using the PM for the first time. The morphology, particles size and quantum efficiency Abbreviations: SSON, SrSi 2 O 2 N 2 ; PM, pechini method; SSM, solid state method; IQE, internal quantum efficiency; EQE, external quantum efficiency. * Corresponding author at: Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005, PR China. Fax: +86 592 2183937. E-mail addresses: dhia_hassan@yahoo.com (D.A. Hassan), rjzeng@xmu.edu.cn (R. Zeng). http://dx.doi.org/10.1016/j.materresbull.2016.01.048 0025-5408/ ã 2016 Published by Elsevier Ltd. Materials Research Bulletin 79 (2016) 69–72 Contents lists available at ScienceDirect Materials Research Bulletin journal homepage: www.else vie r.com/locat e/mat resbu