Original Research Paper Photoluminescence optimization of BCNO phosphors synthesized using citric acid as a carbon source Bebeh W. Nuryadin a , Tri Puspita Pratiwi a , Ferry Iskandar a,⇑ , Mikrajuddin Abdullah a , K. Khairurrijal a , Takashi Ogi b , Kikuo Okuyama b a Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jalan Ganesa 10, Bandung 40132, Indonesia b Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi Hiroshima 739-8527, Japan article info Article history: Received 9 October 2013 Received in revised form 1 January 2014 Accepted 11 January 2014 Available online xxxx Keywords: BCNO phosphors Photoluminescence spectra Citric acid White LED abstract Citric acid was used as carbon source for the optimization of the photoluminescence (PL) performance of boron carbon oxynitride (BCNO) phosphor. Citric acid was chosen as an alternative carbon source because of its simple molecular structure, low decomposition temperature, relative inexpensiveness, and environ- mental friendliness. The prepared sample exhibited a single, homogeneous, and broad photolumines- cence emission band whose peak varied from near-UV (400 nm) to yellow-visible (500 nm) upon excitation at 365 nm. The effects of varying the synthesis temperature, molar ratio of the carbon/boron and nitrogen/boron sources, and addition of SiO 2 nanoparticles on the PL properties were also studied. The optimized BCNO phosphors may find potential use in white LED applications. Ó 2014 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved. 1. Introduction Recently, phosphor-converted white LEDs and multi-chip (RGB) LEDs have become commonplace in the fabrication of white light- emitting diodes (LEDs) [1,2]. The alternative method for fabrication of phosphor-converted white LEDs involves combining yellow- emitting oxynitride phosphors with blue (indium gallium nitride) LEDs [3,4]. Many oxynitride phosphors have been fabricated, and their photoluminescence (PL) properties have been studied. A few examples are Ca-a-SiAlON:Eu 2+ [5], Ce 3+ doped lanthanum silicon oxynitride [6] and MSi 2 O 2 N 2 with M = alkaline earth and boron carbon oxynitride (BCNO) phosphor [7,8]. The BCNO phosphor is a good candidate as a yellow emission phosphor that does not depend on rare-earth materials as the luminescence center [9]. BCNO phosphors have a wide excitation spectral window, from the short UV to blue, and the emission spectra can be tuned from violet, blue, greenish, yellow, to red with relatively high quantum efficiency [10–12]. The BCNO phosphor was synthesized using a facile heating method at low synthesis temperatures (below 900 °C) under atmospheric pressure [13,14]. To produce BCNO phosphor nanoparticles with 5 nm diameters, Lei et al. [15] synthesized BCNO phosphor materials in a salt melt matrix at 700 °C, the prepared samples have PL peaks in the 440–528 nm range. In addition, our group has synthesized a BCNO phosphor, with SiO 2 nanoparticles as an additive matrix, resulting in uniform and relatively high yellow luminescence intensities [16]. Some BCNO phosphor syntheses employ ethylene glycol, tetra- ethylene glycol, polyethylene glycol, polyallylamine, polyethylene- imine, guanidine hydrochloride, and glycerol as carbon sources [12,14,15,17]. However, the use of carbon sources with long hydro- carbon chains and high decomposition temperatures result in the formation of residual carbon due to incomplete combustion pro- cesses [13]. Additionally, carbon sources mentioned above are still relatively expensive for large-scale production. Citric acid has a simple molecular structure, low thermal decomposition temperature, and high chemical reactivity. It is more economical, environmentally friendly, and has structural groups (C–OH) similar to other carbon sources that have been used in previous BCNO phosphor syntheses [17]. We assumed that citric acid could be used as a carbon source to synthesize BCNO phos- phors. The use of citric acid was expected to reduce residual carbon formation, improve the PL properties, and allow for decreased synthesis temperatures. In this study, we report, to the best of our knowledge, the first example of citric acid used as a carbon source in the synthesis of BCNO phosphors. In particular, we systematically investigated the influence of citric acid concentration in the precursor, synthesis temperature, and addition of SiO 2 nanoparticle on the PL properties of the BCNO phosphor material. The crystal structure formation and morphology of the BCNO phosphor is also discussed. 0921-8831/$ - see front matter Ó 2014 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved. http://dx.doi.org/10.1016/j.apt.2014.01.003 ⇑ Corresponding author. Tel.: +62 22 250 0834; fax: +62 22 250 8452. E-mail address: ferry@fi.itb.ac.id (F. Iskandar). Advanced Powder Technology xxx (2014) xxx–xxx Contents lists available at ScienceDirect Advanced Powder Technology journal homepage: www.elsevier.com/locate/apt Please cite this article in press as: B.W. Nuryadin et al., Photoluminescence optimization of BCNO phosphors synthesized using citric acid as a carbon source, Advanced Powder Technology (2014), http://dx.doi.org/10.1016/j.apt.2014.01.003