The Consequences of Decreasing Particle Size on the Raman Spectroscopy of Carbons

2001 ◽  
pp. 169-176 ◽  
Author(s):  
I. Pócsik ◽  
M. Koós ◽  
O. Berkesi
Keyword(s):  
Particle Size ◽  
Raman Spectroscopy

scholarly journals PEMANFAATAN TEKNIK HEM UNTUK PENUMBUHAN CNT DARI GRAFIT MENGGUNAKAN Ni SEBAGAI KATALIS = UTILIZATION OF HEM TECHNIQUE FOR GROWTH OF CNT FROM GRAPHITE POWDERS BY USING Ni AS CATALYST

2016 ◽  
Vol 10 (1) ◽  
pp. 35-40
Author(s):  
Yunasfi . ◽  
P. Purwanto ◽  
Mashadi .
Keyword(s):  
Particle Size ◽  
Raman Spectroscopy ◽  
Electron Microscope ◽  
Carbon Nanotube ◽  
Surface Area ◽  
Transmission Electron Microscope ◽  
Milling Time ◽  
High Energy ◽  
Milling Process ◽  
Transmission Electron

Utilization of HEM (high energy milling) technique for growth of CNT (carbon nanotube) from graphite powders by using Ni as catalyst was carried out. Milling process performed on a mixture of graphite powder and nickel powder (Ni-C powders) with the ratio of weight percent of 98%: 2%, with a variation of milling time between 25 up to 75 hours. Characterization using PSA (Powder Size Analyzer), SAA (Surface Area Analyzer), TEM (Transmission Electron Microscope) and Raman Spectroscopy performed to obtain information about particle size, surface area, morphology and the structure bonding of the milled powder respectively. The analysis results of Ni-C powders using PSA and SAA showed the smallest particle size and biggest surface area obtained after milling process for 50 hours, i.e. 80 nm and 705 m2/g, respectively. TEM observations revealed formation of flat fibers which quantity increased with increasing milling time. This flattened fiber behave as an initiator for the growth of CNTs. Ni-C powder milling for 50 hours results more clearly show the growth of CNTs. Analysis by Raman Spectroscopy showed two bands at 1582 cm−1 as a peak of G band and at 1350 cm-1 as a peak of D band. These spectra are typical for sp2 structure. The position of G band peak is close to 1600 cm-1 as the evidence of a change to nano-crystalline graphite. The highest intensity of D band shown in the milling process for 50 hours, which indicates that this milling time produces more graphite-like structure compared to other conditions, and is predicted good for growing CNTs. AbstrakPemanfaatan teknik HEM (High Energy Milling) untuk penumbuhan CNT (carbon nanotube) dari serbuk grafit dengan menggunakan Ni sebagai katalis. Proses milling dilakukan terhadap campuran serbuk grafit dan serbuk nikel (serbuk Ni-C) dengan perbandingan berat 98% : 2%, dengan variasi waktu milling antara 25-75 jam. Karakterisasi menggunakan fasilitas PSA (Particle Size Analyzer), SAA (Surface Area Analyzer), dan TEM (Transmission Electron Microscope) serta Raman Spektroscopy yang masing-masingnya untuk mendapatkan informasi tentang ukuran partikel, luas permukaan dan morfologi serta struktur ikatan serbuk hasil milling. Hasil analisis serbuk Ni-C dengan PSA dan SAA menunjukkan ukuran partikel paling kecil dan luas permukaan paling besar diperoleh setelah proses milling selama 50 jam, masing-masing 80 nm dan 705 m2/g. Pengamatan TEM menunjukkan serbuk-serbuk berbentuk serat pipih dengan kuantitas yang meningkat dengan bertambahnya waktu milling. Serat pipih ini perupakan cikal bakal penumbuhan CNT. Serbuk Ni-C hasil milling menunjukkan penumbuhan CNT terlihat lebih jelas setelah milling selama 50 jam. Hasil analisis dengan Raman Spectroscopy memperlihatkan puncak G band pada bilangan gelombang 1582 cm−1 yang merupakan spektrum untuk struktur sp2 dari grafit dan puncak D band pada bilangan gelombang 1350 cm-1 yang mungkin merupakan deformasi struktur grafit. Posisi puncak G band mendekati 1600 cm-1 menjadi bukti perubahan ke grafit nano kristal. Intensitas D band tertinggi ditunjukkan oleh sistem komposit Ni-C hasil proses milling selama 50 jam dan hal ini sebagai indikasi bahwa proses milling selama 50 jam terhadap sistem komposit Ni-C lebih berstruktur mirip grafit (graphitic-like material) dibanding kondisi lainnya dan diprediksi bagus untuk menumbuhkan CNT. Dengan demikian, waktu milling yang optimal untuk penumbuhan CNT dari serbuk grafit dengan menggunakan Ni sebagai katalis adalah adalah 50 jam.  

scholarly journals Synthesis and analytical characterization of gold nanoparticles for anticancer drug delivery application

2016 ◽  
Author(s):  
Elżbieta U. Stolarczyk ◽  
Krzysztof Stolarczyk ◽  
Marek Kubiszewski ◽  
Marta Łaszcz ◽  
Wioleta Maruszak
Keyword(s):  
Particle Size ◽  
Gold Nanoparticles ◽  
Raman Spectroscopy ◽  
Capillary Electrophoresis ◽  
Surface Plasmon Resonance ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
Electrochemical Techniques ◽  
Vis Spectroscopy

For many years research has been carried out to form selective drug carriers. Gold nanoparticles (AuNP) are of particular interest. New perspectives of these nanoparticles as drug carries include: the use of drugs which are poorly soluble in water, targeted delivery of drugs, transport by barrier membranes, the possibility of macromolecular drug release, "combined" treatment - two or more drugs, securing faster mechanisms of action and improved efficiency of drugs. Drug-modified gold nanoparticles (R-AuNP) have been synthesized in a single-phase system based on the reduction of hydrogen tetrachloroaurate (III) using the stabilizing ligand. The color change from yellow to deep ruby red indicated the formation of gold nanoparticles. The formation of stabilized gold nanoparticles was confirmed by the observation of the surface plasmon resonance band. Varying drug concentrations and kinds of solvents were used for the reduction of tetrachloroaurate to determine the effect of drug/ligand concentration and solvent type on the formation of AuNPs. The stability of newly synthesized R-AuNPs was characterized using UV-Vis spectroscopy. The conjugated particles (the resulting AuNPs) were characterized by several techniques, including transmission electron microscopy (TEM), UV-Vis spectroscopy, infrared spectroscopy (IR), Raman spectroscopy, nuclear magnetic resonance spectroscopy (NMR), capillary electrophoresis, electrochemical techniques and zeta potential measurement. In any application of the AuNPs, it is important first to determine their basic physico-chemical characteristics, such as, e.g. size, shape, mono- or polydispersity, UV–Vis spectra, electrokinetic potential as well as other special parameters and analytical methods employed in the characterization of the AuNPs. TEM is a powerful and straightforward method for the determination of size (including size distribution) and shape of the AuNPs. UV–Vis absorption spectrophotometry allows for an in situ direct analysis of colloidal solutions. The position of the observed band maxima (typically in the range 500 – 600 nm) is usually related to particle size. However, the position of the surface-plasmon resonance (SPR) maximum cannot be directly related to the particle size of the NPs and other factors have to be considered. The capillary electrophoresis is the method applied to confirm the formation of nanoparticles as well as to determine the drug residuals in the leachate during the purification of the conjugates. By means of infrared and Raman spectroscopy it is possible to study the molecular species deposited on the AuNPs. The NMR spectroscopy and electrochemical techniques are used to confirm the attached drugs. Complete structural characterization of the organic molecules attached to the AuNPs surface was carried out.

Size Effect of Expandable Graphite

2012 ◽  
Vol 499 ◽  
pp. 72-75 ◽  
Author(s):  
Yan Lu
Keyword(s):  
Particle Size ◽  
Raman Spectroscopy ◽  
Raw Materials ◽  
Structural Disorder ◽  
Expandable Graphite ◽  
X Ray Diffraction ◽  
Natural Graphite ◽  
X Ray ◽  
Intercalating Agents ◽  
Scanning Electron

Using three natural graphites with different particle size, 35, 50 and 80 mesh, as raw materials, expandable graphites were prepared by intercalating, water-washing and drying the natural graphites. The products were characterized by X-ray diffraction, Infrared spectroscopy, scanning electron microscope and Raman spectroscopy. Results show that the structure of expandable graphite is affected strongly by the particle size of natural graphite. With increasing the particle size of natural graphite, for expandable graphite, the expansion degree of graphite flakes along the c-axis and the relative ratio of intercalating agents increase, while the structural disorder increases.

Raman Spectroscopy Studies of Nanocrystalline Lead Zirconate Titanate as Functions of Particle Size and Pressure

2015 ◽  
Vol 48 (7) ◽  
pp. 521-527 ◽  
Author(s):  
Zhen Yuan ◽  
Jinlong Zhu ◽  
Shaopeng Zhang ◽  
Xiaohui Wang ◽  
Longtu Li ◽  
...  
Keyword(s):  
Particle Size ◽  
Raman Spectroscopy ◽  
Lead Zirconate Titanate ◽  
Lead Zirconate ◽  
Zirconate Titanate ◽  
Spectroscopy Studies
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