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51.
对以钴、镍、钴/镍、钴/二茂铁、镍/二茂铁和二茂铁为催化剂高温热解法制备的硼碳氮(BCN)纳米管的结构、产率等的影响进行了分析.实验中发现催化剂在BCN纳米管的生长过程中有重要作用.高分辨率透射电子显微镜图像显示在860℃时,以镍/二茂铁、钴/二茂铁为催化剂生成的BCN纳米管具有“竹节状”结构,且管壁较薄,镍、钴或镍/钴作催化剂生成的BCN纳米管不具有明显的“竹节状”结构,管壁较厚,且粗细不均匀,而以二茂铁作催化剂没有BCN纳米管生成.在所有生成的BCN纳米管中含有催化剂颗粒.通过对生成的BCN纳米管的结
关键词:
BCN纳米管
热解
催化剂
拉曼光谱 相似文献
52.
Structural evolution and bandgap modulation of layered β-GeSe2 single crystal under high pressure 下载免费PDF全文
Hengli Xie 《中国物理 B》2022,31(7):76101-076101
Germanium diselenide (GeSe2) is a promising candidate for electronic devices because of its unique crystal structure and optoelectronic properties. However, the evolution of lattice and electronic structure of $β$-GeSe2 at high pressure is still uncertain. Here we prepared high-quality $β$-GeSe2 single crystals by chemical vapor transfer (CVT) technique and performed systematic experimental studies on the evolution of lattice structure and bandgap of $β$-GeSe2 under pressure. High-precision high-pressure ultra low frequency (ULF) Raman scattering and synchrotron angle-dispersive x-ray diffraction (ADXRD) measurements support that no structural phase transition exists under high pressure up to 13.80 GPa, but the structure of $β$-GeSe2 turns into a disordered state near 6.91 GPa and gradually becomes amorphous forming an irreversibly amorphous crystal at 13.80 GPa. Two Raman modes keep softening abnormally upon pressure. The bandgap of $β$-GeSe2 reduced linearly from 2.59 eV to 1.65 eV under pressure with a detectable narrowing of 36.5%, and the sample under pressure performs the piezochromism phenomenon. The bandgap after decompression is smaller than that in the atmospheric pressure environment, which is caused by incomplete recrystallization. These results enrich the insight into the structural and optical properties of $β$-GeSe2 and demonstrate the potential of pressure in modulating the material properties of two-dimensional (2D) Ge-based binary material. 相似文献
53.
Composite nanoparticles (NPs) have the ability of combining materials with different properties together, thus receiving extensive attention in many fields. Here we theoretically investigate the electric field distribution around core/shell NPs (a type of composite NPs) in ferrofluids under the influence of an external magnetic field. The NPs are made of cobalt (ferromagnetic) coated with gold (metallic). Under the influence of the external magnetic field, these NPs will align along the direction of this field, thus forming a chain of NPs. According to Laplace's equations, we obtain electric fields inside and outside the NPs as a function of the incident wavelength by taking into account the mutual interaction between the polarized NPs. Our calculation results show that the electric field distribution is closely related to the resonant incident wavelength, the metallic shell thickness, and the inter-particle distance. These analytical calculations agree well with our numerical simulation results. This kind of field-induced anisotropic soft-matter systems offers the possibility of obtaining an enhanced Raman scattering substrate due to enhanced electric fields. 相似文献
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55.
催化剂对碳纳米管产率及质量的影响 总被引:1,自引:0,他引:1
本文研究了添加钴/二茂铁、镍/二茂铁、钴、镍/钴不同催化剂对高温热解法制备碳纳米管质量、产率等的影响。高分辨率透射电镜图象显示在800℃左右,镍/二茂铁、钴/二茂铁和钴催化条件下,有多壁碳纳米管生成,而用镍/钴作催化剂时,只有直径在0 5μm左右,长度十几个微米的非晶态棒状物生成。通过对生成碳纳米管的质量和产量进行比较,催化剂的催化活性满足二茂铁>钴>镍。简单分析了在碳源高温热解环境下不同金属催化剂的性能差异,并对不同催化条件下生成物的拉曼光谱进行了分析。 相似文献
56.
负热膨胀化合物可调控材料的热膨胀系数, 在复合材料、 精密仪器等方面具有重要的应用前景, 成为近年来化学、 物理和材料工程领域的研究热点之一. 因其晶体结构主要由—M—CN—M—含有双原子氰根(CN)链组成, 许多普鲁士蓝类化合物呈现反常的热膨胀性质. 本文综述了普鲁士蓝类负热膨胀化合物结构、 热膨胀机制与系数调控等方面的研究进展. 以氰根配体数量为分类主线, 将具有反常热膨胀性的氰根配体化合物分为氰化物、 六氰基和八氰基普鲁士蓝类化合物等进行介绍, 从局域结构和平均结构角度分析了N和C原子的横向振动对负热膨胀贡献的角度解释了机理, 从客体离子或分子嵌入的方法分析了热膨胀调控原理, 并对新型普鲁士蓝类负热膨胀化合物的设计及应用进行了展望. 相似文献
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58.
We propose axial line-focused spiral zone plates(ALFSZPs) for generating tightly focused X-ray vortex beams with ultra-long depth of focus(DOF) along the propagation direction. In this typical design, compared with the conventional spiral zone plates(SZPs) under the same numerical aperture(NA), the DOF of ALFSZPs has been extended to an ultra-length by optimizing the corresponding parameters. Besides, it also exhibits lower side lobes and smaller dark cores in the whole focus volume. The diameters of dark cores increase as the topological charge value increases. 相似文献
59.
A new material of Zr0.1Al1.9Mo2.9V0.1O12 is synthesized by the traditional solid state synthesis method.The phase transition,coefficient of thermal expansion,and luminescence properties of Zr0.1Al1.9Mo2.9V0.1O12 are explored with Raman spectrometer,dilatometer,and x-ray diffraction(XRD)diffractometer.The results show that the Zr0.1Al1.9Mo2.9V0.1O12 possesses the strong broad-band luminescence characteristics almost in the whole visible region.The sample is crystallized in a monoclinic structure group of P21/a(No.14)crystallized at room temperature(RT).The crystal is changed from monoclinic to orthorhombic structure when the temperature increases to 463 K.The material has very low thermal expansion performance in a wide temperature range.Its excellent low thermal expansion and strong pale green light properties in a wide temperature range suggest its potential applications in light-emitting diode(LED)and other optoelectronic devices. 相似文献
60.
采用化学共沉淀法制备陶瓷Zr2P2WO12 (ZWP)和金属Ni复合材料粉体,烧结过程中还原剂柠檬酸将金属Ni2+还原.粉体中ZWP粒径100~200 nm,金属Ni粒径50~100 nm,且混合均匀.复合材料块体的制备采用冷压和放电等离子体烧结(SPS)两种方法,结果表明SPS制备的样品具有更好的块体致密度,可达84;以上.研究表明,通过调节Ni离子的掺杂比例可制备出热膨胀系数从负值到正值的可控热膨胀系数复合材料.当Zr2P2WO12/Ni的摩尔比为5∶5时,制备出的材料为近零膨胀复合材料. 相似文献