Multicolor luminescence in oxygen-deficient Tb 3+ -doped calcium aluminogermanate glasses
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Bin Zhu, Shifeng Zhou, Hucheng Yang, and Jianrong Qiua) State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027, People’s Republic of China (Received 7 November 2007; accepted 18 April 2008)
In this paper, we report on the multicolor luminescence in oxygen-deficient Tb3+-doped calcium aluminogermanate glasses. A simple method was proposed to control oxygen-deficient defects in glasses by adding metal Al instead of the corresponding oxide (Al2O3), resulting in efficient blue and red emissions from Tb3+-undoped glasses with 300 and 380 nm excitation wavelengths, respectively. Moreover, in Tb3+-doped oxygen-deficient glasses, bright three-color (sky-blue, green or yellow, and red) luminescence was observed with 300, 380, and 395 nm excitation wavelengths, respectively. These glasses are useful for the fabrication of white light-emitting diode (LED) lighting.
I. INTRODUCTION
Recently, a special issue of Science focused on how scientists and engineers control and use defects in materials.1 Extensive investigations have shown that control and use of defects are crucial for the dramatic performance improvement of materials.2–6 In recent years, the optical properties of Ge-related defects, e.g., oxygendeficient centers in glasses, have been investigated intensively. It is considered that Ge-related defects are closely related to photo-induced refractive index changes. This observation has lead to important applications such as optical fiber gratings, interconnects, and functional components of prospective microscopic photonic devices.7,8 Usually, oxygen-deficient defects are induced by lasers or controlling atmosphere, and various optical functions have been realized.9,10 Here, we report on the tunable luminescence from rare-earth-doped germanate glasses containing oxygen-deficient defects. The glasses were prepared by adding metal Al instead of corresponding oxide (Al2 O 3 ) to introduce oxygendeficient centers in glasses. The glass samples show efficient blue and red light emissions when excited with 300- and 380-nm ultraviolet (UV) light, respectively. It is interesting to note that the oxygen-deficient glass doped a)
Address all correspondence to this author. e-mail: [email protected] Present address: State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027, People’s Republic of China DOI: 10.1557/JMR.2008.0249 1890
http://journals.cambridge.org
J. Mater. Res., Vol. 23, No. 7, Jul 2008 Downloaded: 13 Mar 2015
with Tb3+ ions shows bright three-color (sky-blue, green or yellow, and red) light emission when excited with 300, 380, and 395-nm light.
II. EXPERIMENTAL
The glass composition was 40CaO–30Al2O3–30GeO2 (mol%). To prepare an oxygen-deficient glass sample, part of the Al2O3 was substituted by Al. We also prepared an oxygen-deficient sample doped with Tb3+ ions. The glass samples prepared without Al, using Al instead of 3 mol% Al2O3 and doped with 1 mol% Tb3+, and using Al instead of 10 mol% Al2O3 and doped with 1 mol% Tb3+ are referred to samples A, B, C, and D, res
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