نتایج جستجو برای: vibration band gap

تعداد نتایج: 310115  

Journal: :international journal of nano dimension 0
s. janitabar darzi nuclear science and technology research institute, 11365/8486 tehran, iran a. r. mahjoub department of chemistry, tarbiat modares university, 14115-175 tehran, iran a. bayat department of chemistry, tarbiat modares university, 14115-175 tehran, iran

s-doped and bare mesoporous tio2 were prepared using titanium tetraisopropoxide and thiocarbamide as raw materials. prepared materials were characterized by means of fourier transform infrared spectroscopy ft-ir, thermogravimetry-differential scanning calorimetry (tg-dsc), x-ray diffraction (xrd), uv–vis absorption spectroscopy, brunauer–emmett–teller (bet) specific surface area and barrett–joy...

Journal: :international journal of nanoscience and nanotechnology 2015
a. s. shahvelayati m. sabbaghan s. e. bashtani

zno nanostructures have been synthesized by a simple reflux method, using different ionic liquids, such as 1-benzyl-3-methylimidazolium bromide ([bzmim][br]), 1,1'-(1,4 phenylenebis (methylene)) bis (3-methyl-1h-imidazol-3-ium) bromide ([mm-1,4-dbzim2][br]2) and 1-phenacyl-3-methylimidazolium bromide ([pmim][br]), with different amount of sodium hydroxide in water. also the effect of reaction t...

Journal: :international journal of bio-inorganic hybrid nanomaterials 0

cumn2o4 nanoparticles, a semiconducting materials with tunable functionalities in solid oxide fuel cell, was successfully synthesized via a sol-gel method using its respective metal cations sources i.e. cu2+ and mn2+ in an appropriate complexing agent.the vibrational frequencies below 1000 cm-1 of the obtained materials confirmed the formation of metal-oxygen (m-o:cu-o, mn-o) bond in the sample...

میلانی مقدم, حسین, نصیریان, شهروز,

  In this letter, titania nanopowder and titania-silica nanocomposite were prepared using sol-gel method. Although the size of nanocrystallites and the mass fraction percent age of rutile phase ( after phase transformation ) were increased by increasing calcination in the two samples , their size in titania-silica nanocomposite was smaller than that in pure titania . Moreover, the calculations ...

Journal: :international journal of nano dimension 0
p. rejani nano science research lab, department of chemistry, d.b.college,sasthamcotta, kollam,kerala, india. a. radhakrishnan nano science research lab, department of chemistry, d.b.college,sasthamcotta, kollam,kerala, india. b. beena nano science research lab, department of chemistry, d.b.college,sasthamcotta, kollam,kerala, india.

zno nanorod was prepared by microwave assisted method. the crystal structure of the nano powders were confirmed by x-ray diffraction analysis and the mean particle size was estimated by the scherrer,s formula .the surface morphology of the nano particles were analyzed by   using sem . the absorption spectrum of the material in the uv-vis range was recorded .the energy band gap of the material w...

Journal: :iranian journal of catalysis 2014
m. mohamed jaffer sadiq a. samson nesaraj

in this research work, we report a simple method called reflux condensation method for synthesizing co3o4 nanoparticles using cheap chemicals such as, cobalt acetate (precursor salt), sodium monododecyl sulphate - sds (surfactant) and n, n - dimethylformamide - dmf (solvent). the prepared materials were heat treated at 200, 400, 600 and 800 oc for each 2 h to get phase pure product. the calcine...

2014
Chuan Li Ming Liang Tianyang Wang

Bearing fault can be detected using envelope demodulation of the bearing vibration signal in the resonant frequency band. Hence locating the correct resonant band is the key to successful application of the resonance envelope demodulation. A statistical criterion of the vibration signal can be used to guide the identification of the resonant band. However, a single criterion is often not robust...

In this paper, properties of reflection phase in one-dimensional quaternary photonic crystals combining dispersive meta-materials and positive index materials are investigated by transfer matrix method. Two omnidirectional band gaps are located in the band structure of considered structure. However, we limit our studies to the frequency range of the second wide band gap. We observe that the val...

Journal: :Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy 2008
L Rintoul A S Micallef S E Bottle

The group frequency of the N-O radical stretching vibration has received scant attention in the literature. The few existing treatments of the vibrational spectroscopy of nitroxides are incomplete at best and potentially misleading to workers in the field. To close this gap in the available knowledge, the existing literature on the vibrational spectra of nitroxide stable free radicals is critic...

2011
Juliana C. Oliveira

Phononic band-gap materials prevent elastic waves from propagating at certain frequency ranges. These materials are called Phononic Crystals (PCs). PCs have been applied to manufacture frequency filters, vibration protection devices, waveguide and to improve ultrasound imaging transducers. Periodic band-gap materials are designed by choosing the location and the size of the band gaps. Many work...

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