Author
Nian Wei
Other affiliations: Washington State University
Bio: Nian Wei is an academic researcher from Sichuan University. The author has contributed to research in topics: Transparent ceramics & Ceramic. The author has an hindex of 17, co-authored 59 publications receiving 880 citations. Previous affiliations of Nian Wei include Washington State University.
Topics: Transparent ceramics, Ceramic, Sintering, Yttrium, Grain growth
Papers
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TL;DR: In this paper, the photoluminescence properties of a transparent ceramic phosphor (Y1-xCex)(3)Al5O12 are studied as a function of doping fraction (x = 0.0005-0.0020).
Abstract: We present our recent achievement of a transparent ceramic able to produce white light when directly combined with commercially available blue light emitting diodes. The photoluminescence properties of ceramic phosphor (Y1-xCex)(3)Al5O12 are studied as a function of doping fraction (x = 0.0005-0.0020). The emission color is tunable by variations of Ce3+ concentration and ceramic phosphor thickness. A maximum luminous efficacy exceeding 93 lm/W at a low correlated color temperature of similar to 4600 K is obtained, which is superior to samples made from commercial phosphor powders. Hence, the present transparent ceramic phosphor is expected to be an ideal candidate for generating white light. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4742896]
150 citations
TL;DR: The Nd:YAG transparent ceramics were fabricated by vacuum sintering and the optical properties varied markedly with different post treatments as mentioned in this paper, and the transmittances of the samples increased from 51.2% to 77.2%.
56 citations
TL;DR: In this article, a novel approach to synergetically control the parameters of sizes and densities of the pores quantitatively for low scattering loss Nd:YAG ceramics was presented.
55 citations
TL;DR: In this article, the authors fabricate transparent MgAl(2)O(4) nano-ceramics, which are composed of 40 nm grains, by sintering under high pressure and low temperatures.
Abstract: We fabricate transparent MgAl(2)O(4) nano-ceramics, which are composed of 40 nm grains, by sintering under high pressure and low temperatures. Analysis of the grain size, differential strains, yield strength and porosity obtained from transmission electron microscopy and x-ray diffraction indicates that the pores at the grain boundary triple junctions can retard grain boundary migration and thus prevent grain growth. It is found that the relatively high density for MgAl(2)O(4) nano-ceramics produced at low-temperature and high pressure is attributed mainly to the large energy in the grain exteriors. The decrease in the transparency with increasing temperature (> 700 degrees C) is therefore a result of the light scattering at large pores. On the basis of these results, we propose a mechanism of transparency in MgAl(2)O(4) nano-ceramics.
47 citations
TL;DR: The Nd:YAG transparent ceramics were fabricated by vacuum sintering at 1750°C for 20h, where the raw nanopowders were synthesized by a modified co-precipitation method as mentioned in this paper.
44 citations
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Journal Article•
28,685 citations
TL;DR: The history of white light-emitting diodes (LEDs) can be found in this paper, where the authors review the history of the conception, improvement, and commercialization of the white LED.
Abstract: About twenty years ago, in the autumn of 1996, the first white light-emitting diodes (LEDs) were offered for sale. These then-new devices ushered in a new era in lighting by displacing lower-efficiency conventional light sources including Edison's venerable incandescent lamp as well as the Hg-discharge-based fluorescent lamp. We review the history of the conception, improvement, and commercialization of the white LED. Early models of white LEDs already exceeded the efficiency of low-wattage incandescent lamps, and extraordinary progress has been made during the last 20 years. The review also includes a discussion of advances in blue LED chips, device architecture, light extraction, and phosphors. Finally, we offer a brief outlook on opportunities provided by smart LED technology.
507 citations
TL;DR: In this article, an innovative luminescent material, transparent Ce:YAG phosphor-in-glass (PiG) inorganic color converter, is developed to replace the conventional resin/silicone-based phosphor converter for the construction of high-power WLED.
Abstract: Currently, the major commercial white light-emitting diode (WLED) is the phosphor-converted LED made of the InGaN blue-emitting chip and the Ce3+:Y3Al5O12 (Ce:YAG) yellow phosphor dispersed in organic epoxy resin or silicone. However, the organic binder in high-power WLED may age easily and turn yellow due to the accumulated heat emitted from the chip, which adversely affects the WLED properties such as luminous efficacy and color coordination, and therefore reduces its long-term reliability as well as lifetime. Herein, an innovative luminescent material: transparent Ce:YAG phosphor-in-glass (PiG) inorganic color converter, is developed to replace the conventional resin/silicone-based phosphor converter for the construction of high-power WLED. The PiG-based WLED exhibits not only excellent heat-resistance and humidity-resistance characteristics, but also superior optical performances with a luminous efficacy of 124 lm/W, a correlated color temperature of 6674 K and a color rendering index of 70. This easy fabrication, low-cost and long-lifetime WLED is expected to be a new-generation indoor/outdoor high-power lighting source.
480 citations
TL;DR: Transparent polycrystalline ceramics have found various applications, such as laser hosts, infrared windows/domes, lamp envelopes and transparent armors, due mainly to their processing flexibility in fabricating items with large sizes and complex shapes and more importantly costeffectiveness as mentioned in this paper.
453 citations