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Properties of Bi2O3-BaO-SiO2-RxOy Glass with ZrO2-filler Composite Sealant
HAN Min-Fang, DU Jun-Ping, Yu Li-An
无机材料学报 , 2010, DOI: 10.3724/sp.j.1077.2010.01058
Abstract: It is research focus that composite materials including glass and skeletal structure are used as sealant in solid oxide fuel cell (SOFC). The composite sealant with 10wt%-30wt% ZrO2-filler in the Bi2O3-BaO-SiO2(BiBaSi) glass were researched in order to improve sealing properties at high temperature. As a result, the coefficients of thermal expansion of the composite sealants were increased than that of basic glass. The suitable sealing temperatures of composite sealant vary from the 720 f base glass to 780 860 nd 900 f BiBaSi-10Zr, BiBaSi-20Zr, BiBaSi-30Zr, respectively. ZrO2-fillers in base glass have two roles: Parts of ZrO2-fillers as skeletal structure materials always exist in base glass, which help to maintain the required shape and size of sealant. The other ZrO2-fillers can also drop into the network of the BiBaSi glass and therefore form a new phase Bi4Si3O12. Two kinds of crystal phase of ZrO2 and Bi4Si3O12 coexist in the composite sealant to improve the stability of composite system in high temperature. The properties of sealing materials could be easily controlled in SOFC sealant by changing the amount of ZrO2-fillers in composite materials.
Effect of ZrO2 on Crystallization and Phase Transformation in Low-temperature Processed BaO-Al2O3-SiO2 Glass-ceramics
ZrO2对低温烧结 BaO-Al2O3-SiO2系微晶玻璃析晶和晶型转变的影响

LU Yu-Feng,DU Yong-Guo,XIAO Jia-Yu,ZHANG Wei-Jun,WU Jian-Feng,YANG Guang,WANG Yue-Ran,
芦玉峰
,堵永国,肖加余,张为军,吴剑锋,杨光,王跃然

无机材料学报 , 2008,
Abstract: 用烧结法制备了化学计量比和高Ba含量的两组BaO-Al2O3-SiO2(BAS)系微晶玻璃,采用差示扫描量热法(DSC)和X射线衍射分析(XRD)等手段研究了ZrO2对BAS系微晶玻璃中六方钡长石析晶和六方钡长石向单斜钡长石晶型转变的影响.研究表明,两组BAS系玻璃的烧结温度低于850℃,晶化温度低于900℃.六方钡长石的析出为整体析晶.不加形核剂晶型转变为整体析晶;添加ZrO2晶型转变为表面析晶.提高Ba含量或添加ZrO2促进六方钡长石的析出和晶粒细化.化学计量比的BAS系微晶玻璃中添加ZrO2明显促进晶型转变.高Ba含量的BAS系微晶玻璃中添加ZrO2表现为抑制晶型转变,850℃保温100h不发生转变.
BAO cosmography  [PDF]
Ruth Lazkoz,Jailson Alcaniz,Celia Escamilla-Rivera,Vincenzo Salzano,Irene Sendra
Physics , 2013, DOI: 10.1088/1475-7516/2013/12/005
Abstract: Cosmography provides a model-independent way to map the expansion history of the Universe. In this paper we simulate a Euclid-like survey and explore cosmographic constraints from future Baryonic Acoustic Oscillations (BAO) observations. We derive general expressions for the BAO transverse and radial modes and discuss the optimal order of the cosmographic expansion that provide reliable cosmological constraints. Through constraints on the deceleration and jerk parameters, we show that future BAO data have the potential to provide a model-independent check of the cosmic acceleration as well as a discrimination between the standard $\Lambda$CDM model and alternative mechanisms of cosmic acceleration.
Crystallization Mechanism and Kinetics of BaO-Li2O-ZrO2-SiO2 Glasses
Silveira, Cristian Berto da;Campos, Sílvia Denofre de;Campos, Elvio A. de;Oliveira, Ant?nio Pedro Novaes de;
Materials Research , 2002, DOI: 10.1590/S1516-14392002000100004
Abstract: differential thermal analysis and scanning electron microscopy were used to determine the influence of the addition of bao on the crystallization mechanism of li2o-zro2-sio2 systems. as the concentration of bao in the samples increased, a transition occurred in the predominant crystallization mechanism, which passed from superficial to volumetric. to determine the maximum nucleation rate, the crystallization kinetics of the sample containing 20 mole % bao, which showed the most uniform crystallization, was studied by counting the nuclei with an image analyzer. the first nuclei appeared at the first endothermic inflection point (at the start of tg, at 440 °c), while the maximum number of nuclei was counted at the midpoint of the glass transition region (446 °c). these results are similar to those observed for other materials that crystallize in volume, and confirm scanning electron microscopy data.
Crystallization Mechanism and Kinetics of BaO-Li2O-ZrO2-SiO2 Glasses
Silveira Cristian Berto da,Campos Sílvia Denofre de,Campos Elvio A. de,Oliveira Ant?nio Pedro Novaes de
Materials Research , 2002,
Abstract: Differential thermal analysis and scanning electron microscopy were used to determine the influence of the addition of BaO on the crystallization mechanism of Li2O-ZrO2-SiO2 systems. As the concentration of BaO in the samples increased, a transition occurred in the predominant crystallization mechanism, which passed from superficial to volumetric. To determine the maximum nucleation rate, the crystallization kinetics of the sample containing 20 mole % BaO, which showed the most uniform crystallization, was studied by counting the nuclei with an image analyzer. The first nuclei appeared at the first endothermic inflection point (at the start of Tg, at 440 °C), while the maximum number of nuclei was counted at the midpoint of the glass transition region (446 °C). These results are similar to those observed for other materials that crystallize in volume, and confirm scanning electron microscopy data.
添加Li2O对YSZ电解质性能影响  [PDF]
韩敏芳,焦成冉,熊洁
硅酸盐学报 , 2012,
Abstract: 8%(摩尔分数,下同)Y2O3稳定的ZrO2(8YSZ)是固体氧化物燃料电池(SOFC)中最常用的电解质材料,本文研究了在8YSZ基体中加入n%Li2O(n=0,0.25,0.50,1.00,1.50,1.70,2.00,2.50,3.00)后(记为n%Li2OYSZ)对其晶相结构、晶格常数、烧结性能、微观形貌、电导率及其作为SOFC电解质性能的影响。结果表明,Li2O中的Li+可以固溶到YSZ的晶格内使其晶格常数减小;Li2O的加入量n<1.70时,瓷体在烧结过程中不会发生相变。加入少量的Li2O(n=0.25,0.50)可以提高YSZ的致密度和电导率,0.25%Li2OYSZ和0.50%Li2OYSZ样品800℃的电导率分别高达0.0302S/cm和0.0276S/cm,分别是纯YSZ的1.35和1.24倍;当Li2O含量n≥1.00时,相同条件下烧结体致密度随Li2O加入量的增大而逐渐减小;当n≥1.70时,样品在烧结过程中虽然出现相变,但在高于1400℃可以烧结致密,并得到纯立方相YSZ。将1250℃烧结制得的0.25%Li2OYSZ和0.50%Li2OYSZ作为SOFC电解质的单电池,800℃时的开路电压高于1.0V,说明YSZ中没有出现电子电导,具有比纯YSZ为电解质的单电池更高的性能输出,表现出了良好的应用前景。
Hierarchical clustering and the BAO signature  [PDF]
Wojciech A. Hellwing,Roman Juszkiewicz,Rien van de Weygaert,Maciej Bilicki
Physics , 2013,
Abstract: In this contribution we present the preliminary results regarding the non-linear BAO signal in higher-order statistics of the cosmic density field. We use ensembles of N-body simulations to show that the non-linear evolution changes the amplitudes of the BAO signal, but has a negligible effect on the scale of the BAO feature. The latter observation accompanied by the fact that the BAO feature amplitude roughly doubles as one moves to higher orders, suggests that the higher-order correlation amplitudes can be used as probe of the BAO signal.
Vidros Ceramicos Nanocristalinos Transparentes  [cached]
Rodrigo Santos,Jo?o Bastos,Luís F. Santos,Rui M. Almeida
Ciência & Tecnologia dos Materiais , 2009,
Abstract: Os vidros ceramicos que contêm no seu interior nanocristais com propriedades ópticas n o lineares, nomeadamente a gera o de segundos harmónicos (SHG), têm um enorme potencial de aplica o na área da fotónica, podendo integrar sistemas ópticos e optoelectrónicos. Com este trabalho, pretendeu-se preparar e caracterizar amostras vítreas no sistema GeO2 SiO2 Nb2O5 K2O e produzir vidros ceramicos transparentes nanocristalinos a partir daquelas, privilegiando a cristaliza o em volume. Prepararam-se amostras vítreas no sistema estudado, tendo-se verificado um aumento da densidade e uma diminui o da temperatura de transi o vítrea com o aumento do teor em GeO2. Tratamentos térmicos efectuados às amostras preparadas permitiram identificar as fases cristalinas K3.8Nb5Ge3O20.4 e K3Nb3Si2O13 como sendo as fases correspondentes aos primeiros picos de cristaliza o obtidos por DTA. Um germanosilicato com 50 mol% de formador de vidro revelou capacidade para promover cristaliza o em volume. De facto, obteve-se um vidro ceramico transparente com tamanho de cristais de ~20-25 nm. Glass ceramics containing nanocrystalline phases that present non-linear optical properties, namely second harmonic generation (SHG), have potential application in photonics, namely in all-optical and electro-optical systems. The goal of this work was the preparation and characterization of glass samples in the system GeO2 SiO2 Nb2O5 K2O, as well as the production of transparent, nanocrystalline glass ceramics. The glass samples were prepared and characterized by density, DTA and Raman spectroscopy measurements. An increase in density and a decrease in Tg and Tx-Tg were observed with increasing amount of GeO2. Heat treatments were performed and the crystalline phases K3.8Nb5Ge3O20.4 and K3Nb3Si2O13 were identified and related with the first exothermic peak of the DTA analysis. A germanosilicate composition with 50 mol% of glass former showed good ability to undergo bulk crystallization. In fact, a transparent glass ceramic containing crystal sizes of ~20-25 nm, was obtained.
The Work of Ngo Bao Chau  [PDF]
Thomas C. Hales
Mathematics , 2010,
Abstract: In August 2010, Ngo Bao Chau was awarded a Fields Medal for his deep work relating the Hitchin fibration to the Arthur-Selberg trace formula, and in particular for his proof of the Fundamental Lemma for Lie algebras. This article gives a brief introduction to his work for a general mathematical audience.
Appearance of ferroelectricity in BaO nanowires  [PDF]
Anna N. Morozovska,E. A. Eliseev,Robert Blinc,Maya D. Glinchuk
Physics , 2009,
Abstract: We predict that ferroelectric phase can be induced by the strong intrinsic surface stress inevitably present under the curved surface in the high aspect ratio cylindrical nanoparticles of nonferroelectric binary oxides (BaO, EuO, MgO, etc). We calculated the sizes and temperature range of the ferroelectric phase in BaO nanowires. The analytical calculations were performed within Landau-Ginzburg-Devonshire theory with phenomenological parameters extracted from the first principle calculations [E. Bousquet et al, Strain-induced ferroelectricity in simple rocksalt binary oxides. arXiv:0906.4235v1] and tabulated experimental data. In accordance with our calculations BaO nanowires of radius ~(1-10) nm can be ferroelectric at room temperature (with spontaneous polarization values up to 0.5 C/m2) for the typical surface stress coefficients ~ (10-50) N/m. We hope that our prediction can stimulate both experimental studies of rocksalt binary oxides nanoparticles polar properties as well as the first principle calculations of their spontaneous dipole moment induced by the intrinsic stress under the curved surface.
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