A group to exchange views on the HOT topic of Nanotechnology.

• Nitin Raulji

  Nano suspended particles for water as medium

  Can anyone guide me how to select Nano material for preparing a nano suspended particles with water as medium. We need to basically study effect of electromagnetic field on water molecule inCan anyone guide me how to select Nano material for preparing a nano suspended particles with water as medium. We need to basically study effect of electromagnetic field on water molecule in presence of suspended nano particles. Thanks.

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    Michal Kisielewski replied

    Dear Sai Krishna, please look on the article "Surfactant-Assisted Sol-Gel Synthesis of TiO2 with Uniform Particle Size Distribution" available hereDear Sai Krishna, please look on the article "Surfactant-Assisted Sol-Gel Synthesis of TiO2 with Uniform Particle Size Distribution" available here http://downloads.hindawi.com/journals/ijic/2011/108087.pdf

    32 minutes ago
• Mohammed Razooqi

  FTIR test for semiconductor thin films

  What is the benefit of FTIR (spectroscopy) test for semiconductor thin films and can we find out what kind of semiconductor we can test with it?

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    Ananth Kumar.R.T replied

    Hai Omar, Plz tell me how we can find energy gap from Raman spectra. Suggest me some idea.

    2 days ago
• Suganya Arumugam

  hi, can any one help me in calculating the refractive index of the thin films using reflection and transmission spectra. How to calculate it using formula or using software

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• Gopinath Danda

  In CBH (correlated barrier hopping) mechanism, is there any relation between the total conductivity and the polaron binding energy?

  In CBH, charge carriers hop from one hopping site to another on application of an external electric field. The energy required for a carrier to jump from one site to another is the polaron bindingIn CBH, charge carriers hop from one hopping site to another on application of an external electric field. The energy required for a carrier to jump from one site to another is the polaron binding energy (thats my understanding. Any correction will be appreciated). Now I want to know if the ac conductivity will be higher for a material with higher polaron binding energy, or are they inversely proportional, or not related at all?

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  • 
    Gopinath Danda replied

    Thanks Taras I also looked through a similar paper of S. R. Elliot ["A.c. conduction in amorphous chalcogenide and pnictide semiconductors" // Adv. in Phys. Vol. 36, No. 2, 135-218 (1987)]. ThereThanks Taras I also looked through a similar paper of S. R. Elliot ["A.c. conduction in amorphous chalcogenide and pnictide semiconductors" // Adv. in Phys. Vol. 36, No. 2, 135-218 (1987)]. There also I found a similar equation but in the terms of minimum hopping distance (Rw), which is inversely proportional to polaron binding energy (Wm) [Eq. 48, Pg. 153 of my ref.]; also the ac conductivity was shown to be proportional to Rw^{6} [Eq. 47,49,51, Pg. 152 of my ref.] for narrow-band, broad-band, single electron and 2 electron hopping models, which leads to the the equation you referred to. Deducing from the both the equations (and also logically), more the polaron binding energy (Wm), less is the hopping distance (Rw) and less is/should be the ac conductivity, if we are to consider CBH. But that is not the result I got when I experimented with nano-ZnO. So I guess only two possibilities are there: (a) my results/calculations are wrong (b) I have to propose a new conduction model Well, thanks again for your input Taras.

    4 days ago
• Roshan Sa

  Does anyone know about the reasons of colour changing of ZnO Cobalt doped Sols? What should we do to obtain stable sol without change of colour?

  I used Zinc acetate dehydrate and cobalt nitrate as precursors, methanol as solvent and monoethanolamin as additive, the sol was refluxed for one hour at temperature around 60 degree of Celsius.

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    Justo Arines replied

    Can it be do tu surface plasmon excitation and their resonant frequencies ??

    6 days ago
• Vaishali Patil

  How to check thickness of very very thin films on metal substrate?

  I am depositing thin films on metal substrate such as nickel and copper. The films are very thin. I could not get thickness using cross sectional SEM. Please suggest way. Also how to check surfaceI am depositing thin films on metal substrate such as nickel and copper. The films are very thin. I could not get thickness using cross sectional SEM. Please suggest way. Also how to check surface SEM of samples deposited on metal substrate.

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    Giovanni Bruno replied

    Ellipsometry (SE) can measure at Angstrom resolution. However, reflectometry can be also good if the thickness to be measured is hundred nanometer. Both techniques need specular surfaces..

    9 days ago
• Phani kumar Burlu

  What information can i get from XPS?

  I want to do XPS studies of TiO2 for surface analysis so what else i can get from the XPS studies

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    Nouar Tabet replied

    XPS gives the composition (ratio O/Ti = 2/1 in the case of TiO2)... but more important is the sensitivity of the technique to the chemical environment of the atoms... O1s line would have a givenXPS gives the composition (ratio O/Ti = 2/1 in the case of TiO2)... but more important is the sensitivity of the technique to the chemical environment of the atoms... O1s line would have a given binding energy for oxygen atoms bound to Ti atoms and a different binding energy for oxygen atoms of moisture adsorbed on the surface... You have also to keep in mind that XPS is a SURFACE TECHNIQUE... The depth probed by the technique is few nanometers! It depends basically on the energy of the photoelectrons detected... less kinetic eenrgy ( i.e higher binding energy ), less depth is probed... 5nm is a typical depth..Therefore do not be surprised to see intense peaks of carbon and oxygen from a sample even if it is not supposed to contain any..! (these are atoms of the contamination layer resulting from the exposure of the sample to ambiant atmosphere before analysis)... XPs instruments are ussually equipped with LN2 cooled fracture stages to break the samples under high vacuum so that fresh surfaces can be analyzed... Ion guns are also used to remove the contamination layer (but can induce unwanted changes in the sample) .. They are also used to measure depth profiles (.e. variation of composition versus depth)... Good luck..

    10 days ago
• Sunil Kumar

  Which form of Cobalt is preferable for magnetism in Cobalt doped ZnO? Octahedral or tetrahedral Co2+ in the crystal field of ZnO?

  I need to know what substitution site for Co2+ in ZnO is good for magnetism in Cobalt doped ZnO thin films. Also, please suggest how to get that preferred site occupation for Co2+ in ZnO?
• Dusan K. Bozanic

  What kind of substrates are the most convenient for spin coating of polymers?

  I want to prepare thin polymer films by spin coating technique. Therefore, I need flat substrates like Si wafers, mica, etc., e.g. those with negligible roughness in comparison to film thickness. II want to prepare thin polymer films by spin coating technique. Therefore, I need flat substrates like Si wafers, mica, etc., e.g. those with negligible roughness in comparison to film thickness. I was wondering, if anyone has any suggestions for a suitable substrate of reasonable price. Thanks!

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    CS Sunandana replied

    Research Gate is turning out to be a great forum for free and open exchange of creative and applicable ideas. Shouldn't it find favour with project/thesis advisors as much as their students? AfterResearch Gate is turning out to be a great forum for free and open exchange of creative and applicable ideas. Shouldn't it find favour with project/thesis advisors as much as their students? After all learning and knowledge creation/application are dynamic and ageless processes-more like a river- a perennial river? Yes?

    16 days ago
• Vladimir Uvarov

  Whether it is possible to recognise the left and right NaClO3 crystals using conventional powder XRD method?

  NaClO3 has cubic structure (P213 (n.198) space group). NaClO3 crystals can possess the left or right symmetry.
• Raj Gupta

  How to calculate size of nanoparticles using from UV VIS spectra?

  Is there any online portal where I can upload the uv vis spectra and get the size statistics of nanoparticles?

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    Dusan K. Bozanic replied

    Hello Raj, You can use Brus equation for this. It is quite simple, here: http://en.wikipedia.org/wiki/Brus_equation . In this page, the example is for CdSe, but there should be no problem to findHello Raj, You can use Brus equation for this. It is quite simple, here: http://en.wikipedia.org/wiki/Brus_equation . In this page, the example is for CdSe, but there should be no problem to find correct parameters for CdS, Just keep in mind that deltaEgap=Egap(nano)- Egap(bulk), and that Egap(nano) can be calculated from the onset of your absorption spectra as 1240/lambda(onset in nm). Hope this helps!

    20 days ago
• Juliano Libardi

  How to determine the leakage current from I-V curve of a thin film (TiO2)?

  Thin film electrical characterization

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  • 
    Syed Malik replied

    as what Nouar and Phani mentioned earlier, TiO2 like ZnO is a semiconductor. so we cannot say it is a leakage current, unless in reverse bias.

    21 days ago
• Sunil Kumar

  How to maintain the molar ratio 1:1 for a salt and an additive solvent in a solution?

  I need to know how to calculate the amount of Zinc acetate and monoethanolamine (MEA) so that the molar ratio of Zn^2+/MEA remains 1:1 in solvent like alcohol? A brief calculation method would beI need to know how to calculate the amount of Zinc acetate and monoethanolamine (MEA) so that the molar ratio of Zn^2+/MEA remains 1:1 in solvent like alcohol? A brief calculation method would be much appreciated.
• Magesan Paramanandham

  What is the role of surfactant during the synthesis of nanoparticles by sol-gel method?

  I have read some papers

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  • 
    mohamen w replied

    dear Gowhar , my main material is diatomite and substrate is glass or silicon and using sol-gel method , so need materials mixing with diatomite for get to nano porous

    25 days ago
• Muhammed ALI A.V

  How does grain size depend on the optical energy band gap of a thin film sample?

  For example, increasing the thickness of the film causes a decrease in grain size, as a result of the increase in energy band gap. So how does the grain size depends on energy band gap?

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  • 
    Sergiusz Patela replied

    Dear Jaymin Ray, Once grain size falls below ~100 nm, quantum effects manifest themselves. Small grains work as quantum wells, and bandgap depends on the grain size. Many examples available, lookDear Jaymin Ray, Once grain size falls below ~100 nm, quantum effects manifest themselves. Small grains work as quantum wells, and bandgap depends on the grain size. Many examples available, look eg. fig. 5.4, p. 111, Nanophotonics and Nanofabrication. Edited by Motoichi Ohtsu, Copyright
    2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim ISBN: 978-3-527-32121-6 (just the first thing I got from the Web).

    26 days ago