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41.
42.
金属硝酸盐中加入适量的添加剂均匀混合后,利用黑索金炸药(RDX)爆轰合成铝酸锶铕(SrAl2O4:Eu2 、Dy3 )长余辉发光材料的实验研究.通过X射线粉晶衍射仪(XRD)和TEM对爆轰灰及高温处理后的爆轰灰进行测试分析.研究表明:合成出的爆轰灰中含有SrAl2O4相,在空气中经过600℃,1h处理后,合成的SrAl2O4与标准卡JCPDS(No.34-0379)基本一致.粒度主要分布在20~60nm之间,平均粒径约为35nm.经紫外灯照射后,爆轰灰及处理的爆轰灰都能发出浅绿色余辉. 相似文献
43.
The grain-boundary chemistry of magnesium aluminate spinel solid solutions MgO· n Al2 O3 in which grain growth measurements were reported in part I has been investigated in order to understand the mechanism of grain-boundary migration. It is found that although segregation of impurity Ca and Si is common, much larger deviations in grain-boundary stoichiometry are present. There is an excess of Al and O relative to Mg at grain boundaries in all compositions. Grain-boundary migration appears to be rate-limited by solute drag from intrinsic defects accommodating lattice nonstoichiometry, rather than by extrinsic solutes, consistent with the observed impurity tolerance of grain-boundary mobility. Different rate-limiting defects are proposed for magnesia-rich and alumina-rich spinels. 相似文献
44.
J. K. Richard Weber Johan G. Abadie Thomas S. Key Kirsten Hiera Paul C. Nordine Ronald W. Waynant Ilko K. Ilev 《Journal of the American Ceramic Society》2002,85(5):1309-1311
Single-phase glasses containing 37.5 mol% Y2 O3 , 7 mol% La2 O3 , and 1 mol% Pr, Ho, Nd, Er, Sm, Tm, Eu, or Yb oxide substituted for part of the Y2 O3 were synthesized by containerless melting. The spectral transmission and absorption cross sections of the glasses were determined at wavelengths from 360 to 3300 nm. The electronic transitions were broadened compared with results obtained in a crystalline yttrium aluminum garnet (YAG) host. The infrared transmission of the host glass extended to 6000 nm. The optical and physicochemical properties of these glasses are well suited for optical device applications. 相似文献
45.
The eutectic composition between Y4 Al2 O9 and Y2 O3 was determined using electron probe microanalysis (EPMA) on directionally solidified specimens with hypo- and hypereutectic compositions. The microstructures of the specimens as a function of composition differ considerably with small deviation from the eutectic composition (70.5 mol% Y2 O3 and 29.5 mol% Al2 O3 ). Based on the current results and other published data, the pseudobinary system between Al2 O3 and Y2 O3 is revised. 相似文献
46.
Zhizhan Chen Erwei Shi Wenjun Li Yanqing Zheng Nanchun Wu Weizhuo Zhong 《Journal of the American Ceramic Society》2002,85(12):2949-2955
Nanosized CoAl2 O4 and ZnAl2 O4 powders with particle sizes of 67 and 6.5 nm are synthesized under hydrothermal conditions at 245°C for 20 h. The precursors are reacted at different temperatures to provide intermediate phase transformations using X-ray diffraction (XRD), infrared (IR) spectra, and thermal gravity and differential thermal analysis (TG-DTA). XRD patterns and IR spectra demonstrate that the CoAl layered double hydroxide structure (CoAl-LDHs) is more stable than ZnAl layered double hydroxide structure (ZnAl-LDHs) when they are hydrothermally treated. The different thermal stability of the CoAl- and ZnAl-LDHs results in the different aluminum source, e.g., β-Al(OH)3 for ZnAl2 O4 vs γ-AlO(OH) for CoAl2 O4 , when the aluminate spinels are formed. The different aluminum sources lead to the particle size difference. The phenomenon is reasonably expounded based on the nucleation theory from the microscopic scale. 相似文献
47.
选用Ca(OH) 2 饱和溶液和AlCl3溶液为初始原料 ,按Al3+ 与Ca2 + 的摩尔比为 2 .2配成混合溶液 ,在常温、高pH值下 ,先合成前驱体铝酸钙水化沉淀物 ,再经110 0℃煅烧制成高活性、高纯度的铝酸钙粉体。煅烧后粉体的XRD分析和SEM观察显示 :合成物于 10 0 0℃煅烧有大量铝酸钙矿物形成 ,110 0℃时可获得稳定的铝酸钙矿物 ,它是以CA为主晶相 ,并含有少量CA2的二元混合物 ,其中位径d50 约为 0 .6 6 μm ,比表面积为13m2 ·g- 1。 相似文献
48.
介绍了硫铝酸盐秸秆混凝土这种新型绿色环保混凝土材料的力学性能及其材料特点.主要以绿色环保型混凝土的材料性能分析为研究目的,展示新型绿色环保材料的优势特性.通过对硫铝酸盐秸秆混凝土力学试验的结果分析,认为其将成为被东北地区广泛应用,具有良好保温、隔热、轻质等优良性能的新型绿色环保材料。 相似文献
49.
Tamino Hirsch Zichen Lu Dietmar Stephan 《Journal of the American Ceramic Society》2021,104(9):4829-4842
The differences between the hydration of Portland cements with single and with mixed sulfate carriers in the presence of triethanolamine (TEA) were investigated, and possible mechanisms were proposed. Without TEA, cements with different types of sulfate carriers (gypsum, hemihydrate, anhydrite, and mixture of these) have a comparable hydration process at the same molar amount of calcium sulfate. At a TEA dosage of 0.5 wt.%, the sample with a mixture of three sulfate carriers shows substantially stronger retardation of the C3S (This publication uses the cement chemist notation: C3S = Ca3SiO5, C2S = Ca2SiO4, C3A = Ca3Al2O6, C4AF = Ca2(Al, Fe)2O5.) hydration than the cements with only one of these sulfate carriers, which is likely caused by the rapid formation of ettringite and the fast depletion of all sulfate carriers. These effects indicate that TEA influences the balance of sulfate carriers with aluminate-containing clinker phases. On the one hand, TEA can disturb the original sulfate balance due to the accelerated dissolution of aluminate-containing clinker phases, especially C4AF. On the other hand, these effects are closely related to the types and amounts of the sulfate carriers in the cement. A higher amount of sulfate carriers can minimize the TEA-related retardation of the C3S hydration, and hemihydrate shows the strongest impact at the same calcium sulfate quantity. 相似文献
50.