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以二氧化硅,三氧化二铝,氧化钙和氧化镁为主要原料,分别采用微波辐射和传统电加热制备了一系列CaO-MgO-Al2O3-SiO2 (CMAS)系微晶玻璃材料,对比两种方法的热处理制度对微晶玻璃结构与性能的影响,并进一步讨论了微波非热效应的影响.利用DTA、XRD、SEM和综合力学性能仪等手段,研究了两种对该系微晶玻璃显微结构及性能的影响.实验结果表明,两种方法制备的微晶玻璃主晶相均为辉石相,力学性能也基本相当.与传统热处理方法相比,微波法可在更短时间内制备出性能较好的微晶玻璃材料,微波非热效应有助于降低其晶化温度. 相似文献
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Nanogap plasmonic structures with strong coupling between separated components have different responses to orthogonal-polarized light, giving rise to giant optical chirality. Here, we proposed a three-dimensional(3D) nanostructure that consists of two vertically and twistedly aligned nanogaps, showing the hybridized charge distribution within 3D structures.It is discovered that the structure twisted by 60° exhibits plasmonic coupling behavior with/without gap modes for different circular-polarized plane waves, showing giant chiral response of 60% at the wavelength of 1550 nm. By controlling the disk radius and the insulator layer, the circular dichroism signal can be further tuned between 1538 and 1626 nm. 相似文献
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57Fe Mössbauer spectrometry: A powerful technique to analyze the magnetic and phase characteristics in RE–Fe–B permanent magnets 下载免费PDF全文
This review summarizes the recent advances on the application of 57Fe M?ssbauer spectrometry to study the magnetic and phase characteristics of Nd–Fe–B-based permanent magnets. First of all, the hyperfine structures of the Ce2Fe14B,(Ce,Nd)2Fe14B and MM2Fe14B phases are well-defined by using the model based on the Wigner-Seitz analysis of the crystal structure. The results show that the isomer shift δ and the quadrupole splitting ?EQ of those 2:14:1 phases show minor changes with the Nd content, while the hyperfine field Bhfincreases monotonically with increasing Nd content and its value is influenced by the element segregation and phase separation in the 2:14:1 phase. Then, the hyperfine structures of the low fraction secondary phases are determined by the 57Fe M?ssbauer spectrometry due to its high sensitivity. On this basis,the content, magnetic behavior, and magnetization of the REFe2 phase, the amorphous grain boundary(GB) phase, and the amorphous worm-like phase, as well as their effects on the magnetic properties, are systematically studied. 相似文献
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采用熔融法,利用纯化学试剂制备了CaO-A12O3-MgO-SiO2 (CAMS)系微晶玻璃,利用DTA、XRD、拉曼光谱仪等研究了Fe2O3对微晶玻璃析晶特性的影响规律,微晶玻璃的物化性能由抗折强度、杨氏模量、剪切模量、泊松比、维氏硬度等进行评价.结果表明,微晶玻璃的析晶特性随着Fe2 O3含量的增加而增强,对应母体玻璃中首先出现富铁相,进而促进辉石主晶相的析出.微晶玻璃的断裂特性及裂纹扩展方式均随析晶度的提高得到明显改善.但过量的Fe2O3添加则对微晶玻璃的析晶特性无明显影响,反而降低了玻璃相的致密性.微晶玻璃的耐酸性、抗折强度、杨氏模量及剪切模量均呈现先增加后降低的趋势,微晶玻璃的Fe2 O3含量为6.6wt;时综合性能最优. 相似文献
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本文通过建立有机工质/DMF混合工质相平衡计算模型,对比了纯R245fa和其与DMF的混合物二者对有机朗肯循环中膨胀机做功的影响。其结果表明,在膨胀机进出口压比受限的情况下,利用R245fa/DMF的特殊物性,改变R245fa的液相摩尔分数,可在获得高蒸气温度的同时降低相平衡压力,并在同压比条件下获得更高的膨胀机进出口焓差,当R245fa的液相摩尔分数为0.64,温度为403 K时,焓差较纯质时由19.2 kJ/kg增大至22.84 kJ/kg;此外采用混合工质时的热效率较同压比时的纯工质高06%~1.3%。 相似文献
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研究了Cr添加量对V_(2.1)Ti Ni_(0.3)Crx(x=0,0.2,0.4,0.6)贮氢合金的结构和电化学性能的影响。结果表明,所有合金均由V基固溶体主相和Ti Ni基第二相组成,且第二相呈网状分布在晶界上,部分呈颗粒状分布于合金主相之中。随着Cr含量增大,合金主相的晶胞体积与合金电极的最大放电容量逐渐减小,而循环稳定性逐渐增加,同时合金电极的动力学性能得到改善。在合金中添加Cr使合金电极的活化性能变差,但添加量的进一步增多对其活化性能影响不大。综合考虑,V_(2.1)Ti Ni_(0.3)Cr_(0.4)合金的电化学性能最好,最大放电容量可达442.20 m Ah·g~(-1),20次充放电循环后容量保持率达81.91%。 相似文献
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利用磁控溅射方法,在(100),(110)和(111)LaAlO3(LAO)衬底上制备得到了不同生长方向的La0.7Sr0.3MnO3(LSMO)薄膜并对其晶体结构及磁电学性能进行了系统研究。AFM图揭示出(100),(110)和(111)生长方向的LSMO薄膜分别具有圆形、长条形和点状的表面晶粒形貌。磁电学测试结果表明不同生长方向的LSMO薄膜磁电学性能与其应变程度有关。(111)生长方向的LSMO薄膜由于按最密排面生长,晶格畸变很小,从而具有相对最大的磁饱和强度值和最低的电阻。 相似文献