Synthesis and luminescent properties of a new red-emitting phosphor for solid-state lighting: Eu 0.1 Gd x La 1.9x TeO 6 (0.02pxp0.1) Rodrigo Castillo, Jaime Llanos à Departamento de Quı ´mica, Universidad Cato ´lica del Norte, Avda. Angamos 0610, Casilla 1280, Antofagasta, Chile article info Article history: Received 5 September 2008 Received in revised form 18 November 2008 Accepted 25 November 2008 Available online 6 December 2008 PACS: 78.55.m 78.55.Hx Keywords: Photoluminescence Phosphors Inorganic compounds Optical properties abstract The photoluminescence (PL) emission and excitation behavior of red-emitting Eu 0.1 Gd x La 1.9x TeO 6 (0.02pxp0.1) powder phosphors is reported. Three dominant bands centered at 395, 466 and 534 nm characterized the excitation spectrum. Under the excitation of 395 nm UV light, the emission spectrum exhibits an intense peak centered at 616nm corresponding to the 5 D 0 - 7 F 2 transition of Eu 3+ . Because the f-f transitions are located in the wavelength range of blue or near-UV range, optimized phosphor, Eu 0.10 Gd 0.08 La 1.82 TeO 6 , is a promising material for solid-state lighting based on GaN LEDs applications. & 2008 Elsevier B.V. All rights reserved. 1. Introduction Since the pioneering work of Nakamura in 1993 [1], the blue- emitting GaN light emitting diode (LED) brought a significant revolution in lighting technology. Then, the first commercial white-emitting LED solid-state lighting (SSL) was developed using this blue-emitting LED in 1997 [2]. It is the combination of a blue LED with the yellow yttrium aluminum garnet (YAG:Ce 3+ ) phosphor, in which the phosphor absorbs blue light (l460 nm) and emits yellow light [3]. The mixture of the blue light from the LED and yellow light from the phosphor results in white light. These types of devices have a problem of low color reproducibility because the degradation rates of LED and phosphor are not isochronous; thus, in the scheme of the blue LED plus yellow phosphor there appears a color shift [4]. Presently, the emission bands of LEDs are shifted to the near-UV range, and another approach to assemble the SSL devices is proposed. The near-UV LED is combined with the tri-color phosphors (red, blue and green), giving white light. Here the color shift is reduced because the visible emission in these devices is mainly from the phosphors rather than from LED and the variations of the emission features of the TBC phosphors with temperature are in similar rates. The phosphors materials for current use in solid-state lighting are Y 2 O 2 S:Eu 3+ for red, ZnS:(Cu + ,Al 3+ ) for green, and BaMgAl 10 O 17 :Eu 2+ (BAM) for blue [5]. The red phosphors suitable for use in SSL devices do not have enough absorption in the near-UV region, so it is necessary to use a phosphor mixture containing 80% red, 10% green and 10% blue in order to obtain good color rendering [6,7]. According to Wang et al. [8] red phosphors are the bottleneck for the advancement of SSL. In a previous paper, we have successfully synthesized the red- emitting La 2 TeO 6 :Eu 3+ phosphor (l em ¼ 616 nm). The phosphor La 2x Eu x TeO 6 emits under the excitation of 254 nm UV light [9]. At this time, we have started developing new red phosphors that are optimized for excitation at wavelengths in the near-UV region. In the present paper, we report on the preparation and the characterization as well as the photoluminescence properties of Eu 0.1 Gd x La 1.9x TeO 6 phosphor (0.02pxp0.1). Our research revealed that the red-emitting Gd 3+ -doped phosphors (La 1,90 Eu 0.10 )TeO 6 have a relatively strong absorption in the near-UV spectral region; this property converts these materials into interesting candidates for red phosphors in the SSL. 2. Experimental All phosphors were synthesized starting from the respective oxide (Eu 2 O 3 Aldrich 99.99% pure, Gd 2 O 3 Aldrich 99.99% pure, La 2 O 3 Aldrich 99.99%) and elemental tellurium (Aldrich 99.99% pure). The syntheses of the samples were carried out in three ARTICLE IN PRESS Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jlumin Journal of Luminescence 0022-2313/$ - see front matter & 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jlumin.2008.11.016 à Corresponding author. Tel.: +56 55 355624; fax: +56 55 355632. E-mail address: jllanos@ucn.cl (J. Llanos). Journal of Luminescence 129 (2009) 465–468