共查询到18条相似文献,搜索用时 93 毫秒
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碳原料结构对激光法合成纳米金刚石的影响 总被引:1,自引:0,他引:1
为了确定在较低激光能量密度下(10^6W/cm^2)激光法合成纳米金刚石最适宜的碳原料,研究了三种结构不同的碳原料(炭黑、片状石墨、土状石墨)对合成纳米金刚石的影响,采用拉曼光谱对碳原料的结构进行了分析,结果显示炭黑、土状石墨和片状石墨这三种碳原料的结晶程度依次增强,用Nd:YAG脉冲激光分别轰击不同碳原料的悬浮液,实验产物的透射电镜分析显示在激光照射炭黑和片状石墨的产物中没有金刚石生成,而在激光照射石墨的产物中发现了立方结构的金刚石,其颗粒尺寸约为5Bin.因此,在10^6W/cm^2的脉冲激光作用下,无序炭黑和结晶较完整的片状石墨均不利于合成金刚石,只有有序化程度适中的土状石墨有利于合成金刚石. 相似文献
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该项目采用高功率准分子激光照射固体碳靶,产生高能等离子体,在室温条件下快速沉积高品质大面积均匀纳米金刚石膜。经过三年攻关,已顺利完成各项任务指标。1 自行设计、研制出“准分子激光制备纳米金刚石膜装置” 该装置主要由生长腔、多功能辅助装置及控制系统等组成。主要性能如下①生长腔容积60L,真空度可达到1.33×10~(-4)Pa。②腔内设有旋转+摆动多工位衬底台、旋转靶台、多种强场发生装置。③腔壁设监测窗口、红外、紫外光学窗口和电力、动力、辅 相似文献
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人工合成羟基磷灰石(HAP)具有良好生物相容性,它与脊椎动物的牙、骨骼中HAP的组成及原子水平上的结构极为相似,但其显微组织结构差异较大。本文研究了激光辐照对人工合成HAP显微组织结构的影响。结果表明,在适宜的工艺参数范围内,激光处理后未发现“脱羟”,仍显示HAP的特征峰。且HAP的组织细化,形态改变,结构缺陷增加等,与自然骨内HAP的近似程度增加。 相似文献
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用紫外脉冲激光淀积方法在Pt/TiO2/SiO2/Si(001)衬底上制备了La1-xSrxCoO3/Pb(Ta0.05Zr0.48Ti0.47)O3(PTZT)/La1-xSrxCoO3异质结构薄膜。发现底电极La0.25Sr0.75CoO3可以诱导PTZT薄膜沿(001)方向取向生长。在500kHz和5V的工作电压下铁电电容器La0.25Sr0.75CoO3/PTZT/La0.25Sr0.75CoO3经过5×1010次反转之后,仍保持其初始电极化的96%。此异质结构横截面的扫描电镜照片表明界面上没有明显的因化学反应导致的第二相存在。 相似文献
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This work describes a cost-effective single step technique for the preparation of Au nanostructures of many anisotropic shapes from Au nanorods by irradiating them with different laser energies (2.71, 2.54, and 2.41 eV). A variety of many irregular Au nanomorphologies such as multifaceted polygonal spheres (10–20 nm), low aspect ratio rods, oval egg shapes, squares, pentagons, and nanocapsules of varying sizes were formed after laser exposure. The small irregular shaped particles with new surface exposed atoms having cutting edges and sharp corners affect the optical, electrokinetic, and catalytic properties of fragmented Au nanoparticles. The percentage decomposition of Au nanorods is found to increase as 59% > 69% > 72% with increased energy of laser exposure; 2.41 eV (514.7 nm) > 2.50 eV (488 nm) > 2.71 eV (457.9 nm), as determined from the TEM images. The formation of quantum sized paticles upon laser irradiation results in the increase of zeta potential from +50.0 to +57.5 mV and conductance values. The co-catalytic activity of photofragmented Au nanorods is ~20–25% higher than that of bare nanorods for benzaldehyde photooxidation. 相似文献
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碳纳米材料具有特殊的力学、电学及物化性能,在微电子、航空航天、军用材料等领域具有广阔的应用前景,利用脉冲激光高效、可控制备新型碳纳米材料已成为研究热点。简要介绍了激光与碳材料的相互作用及纳米粒子的成形机理,详细阐述了液相脉冲激光制备纳米金刚石、碳纳米管、石墨烯等碳纳米材料的过程及其影响因素,并展望了激光轰击石墨制备碳纳米材料的主要研究方向。 相似文献
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采用刷涂的方法制备了一种新型的片状石墨增强钡酚醛树脂基复合材料, 并采用重频激光辐照的方法, 对其耐烧蚀性能进行了研究. 研究结果表明: 片状石墨增强钡酚醛树脂基复合材料在平均功率密度为1700 J/cm2的重频激光辐照下的热烧蚀率为32.8 μg/J, 耐激光烧蚀性能明显高于碳纤维增强的钡酚醛树脂基复合材料和钡酚醛树脂; 片状石墨增强钡酚醛树脂基复合材料中的片状石墨呈近平行的层状分布方式, 在激光辐照过程中能对入射激光起到平面反射作用, 从而有效地降低激光辐照的能量沉积; 片状石墨的片型对复合材料的耐烧蚀性能有影响, φ0.5 mm的片状石墨增强的复合材料的耐激光烧蚀性能最好. 相似文献
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P. Rodière J. P. Brison A. D. Huxley F. Rullier Albenque J. Flouquet 《Journal of Low Temperature Physics》2003,132(1-2):119-134
We present transport and specific heat measurements on high quality single crystals of UPt3 before and after irradiation by high energy electrons. The induced changes of the superconducting critical temperature are found to depend strongly on the distance from the irradiated surface. The dramatic effects of the irradiation on the specific heat in the superconducting state can then be simply explained in terms of an inhomogeneous distribution of superconducting transition temperatures. The question of the failure of the universal limit in the heat transport of UPt3 is reexamined, and the conditions for a clean experimental test are established. 相似文献