Papers by Keyword: YAG

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Authors: Cheng Zhang, Qiang Li, Dan Yu Jiang
Abstract: This paper reports a novel route to synthesize nano particles of YAG:Ce3+ luminescent materials via polymer gel precursor. In an aqueous solution containing Y(NO3)3, Ce(NO3)3 and Al(NO3)3, citric acid was added to improve the stability of the solution. Then, acrylamide and N,N`-methylenebis- acrylamide were added. The polymerization of mixture solution was initiated by adding (NH4)2S2O8. By heating the solution at 80oC for 3 h, a transparent gel was obtained. The gel was firstly transformed into active carbon by soaking it at 700oC in ultrahigh pure N2 atmosphere. Carbon in as-received mixture was then removed when the atmosphere was changed from nitrogen to air at the same heating temperature. Well dispersive nano powders of single phase YAG:Ce3+ were thus obtained. XRD, SEM and BET were used to study the characteristics of as-prepared nano YAG:Ce3+ powders.
Authors: R. Krsmanović, P. Canton, A. Speghini, M. Bettinelli, Stefano Polizzi
Authors: E. Sani, E. Favilla, M. Ciofini, A. Lapucci, G. Bezzi, C. Mingazzini, S. Sangiorgi
Abstract: Highly-transparent Nd:YAG ceramic pellets have been produced, characterized and compared with Nd:YAG commercial ceramics and single crystals. The obtained results are promising for laser applications.
Authors: Hong Yu Chen, Ru Yang
Abstract: YAG precursors were co–precipitated from a mixed solution of aluminum and yttrium nitrates using urea as precipitant. After being washed by ethanol several times, the gel–like precursor was dispersed in absolute ethanol to form suspended liquid. The mixture was placed into a high–pressure autoclave, which followed by heating ethanol to supercritical state (Tc > 243°C and Pc > 6.3Mpa). The precursor dried via supercritical ethanol fluid technique was sintered at different temperature according to requirement. The phase transformation, composition and micro–structural features of the products were characterized by XRD, TG/DSC, BET and TEM techniques. It was found that after supercritical ethanol fluid drying the precursor was well dispersed, uniform and caused better sinterability of the resultant YAG powder. XRD results indicated that the precursor was partial crystalline and the pure phase YAG can be obtained at 1200°C calcinated for 2h. TG/DSC revealed the formation process of YAG phase. The averaged size of YAG nanocrystalline powder was 30–40nm and well dispersed according to TEM.
Authors: Shi Min Zhou, Chao Yu, Cheng Ji Deng, Hong Xi Zhu, Wen Jie Yuan
Abstract: The reaction process of synthesis of Al4SiC4 from Al, Si and graphite powders and the effects of Y2O3 on synthesis and microstructure of Al4SiC4 were investigated in this paper. The results show that no substantial changes in the formation of Al4SiC4 content with or without addition of Y2O3. The addition of Y2O3 to Al, Si and carbon powder mixtures was found to be effective for obtaining tabular grains of Al4SiC4. Conversely, Al4SiC4 grains existed as irregular granules without addition of Y2O3.
Authors: Shi Bin Li, Jie Guang Song, Hong Ying Ru, Xiao Bo Bai
Abstract: The shell structure YAG composite powders with different volume fraction (15, 20 and 25vol%) micro h-BN have been prepared by co-precipitation process. The bulk composites were performed by pressure sintering at 1600°C under a pressure of 30MPa in vacuum. The mechanical properties (elastic modulus, hardness, and fracture toughness) and relative density of the composites were investigated detailedly. Furthermore, phase composition and microstructure of the composites were analyzed thoroughly by X-ray diffraction, scanning electron microscopy. Meanwhile, good machinability is maintained due to the low hardness of the second phase.
Authors: Ming Han Xu, Jie Guang Song, Rui Hua Wang, Shi Bin Li, Ning Wang, Si Yuan Yu, Han Xing Yan, Ting Ting Xiao, Fei Chen
Abstract: Yttrium aluminum garnet (YAG) with a chemical composition of Y3Al5O12 is an important advanced structural and functional material due to some excellent properties. The porous YAG ceramics were prepared via vacuum sintering technology, the effect of sintering aids on the properties of porous YAG ceramics were investigated in this paper. Through an analysis and discussion, the conclusions are that the porosity increases with the increasing sintering temperature from 1300°C to 1500°C, the pore is moved to the surface of sample, which forms the open pore to make the porosity increase, the more and bigger sintering neck is increased. Porous YAG ceramics are sintered at 1500°C, the regular outside shapes of porous YAG ceramic are kept using CaO and MgO as sintering aids, the outside shape of porous YAG ceramic is wrecked using Al2O3 as sintering aids, which shows the over fired phenomenon.
Authors: Rong Feng Wang, De Ming Zhang, Ou Yang Zhuang, Hai Lin Xu, Wen Sheng Huang, Da Ming Xie
Abstract: A series of alumina cores with different content of yttria were prepared by sintered at 1450°C. The flexural strength at room temperature, high temperature deformation and shrinkage rate of alumina based ceramic core were determined. the phase evolution and microstructure were studied by scanning electron microscopy (SEM) ,X-ray diffraction (XRD).The optimal yttria content on the combined properties of these cores were discussed. The results explained that The Al2O3 particles reacted with some Y2O3 particles to form a polycrystalline composition 3Y2O3·5Al2O3 (YAG), which activated the lattice and promoted sintering. Most of yttria, however, were concentrated in the ceramic grain boundaries, playing a role in improving grain refinement and microstructure; the cores achieved the best comprehensive performance when the content of yttria was 10%.
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