Nanostructured Materials - Science topic

I think, it will not be appropriate to conclude that, all hydrothermal synthesis act slow in general. Anyway, I can point out a few reasons:

1. Hydrothermal reaction is preferred over wet chemical (one pot or hot injection techniques) or open air solid state synthesis if the temperature requirement is significantly high or open air environment is prohibited. In hydrothermal, due to closed volume, high pressure is built up, so the threshold temperature for the reaction drops significantly. So, in low temperature and high pressure conditions, the reaction take place. Naturally, to reach the threshold pressure, some time is required and only after that nucleation can occur.

2. The reaction kinetics slow down due to smaller temperature than corresponding one pot or hot injection techniques.

3. In most wet chemical synthesis, continuous (magnetic) stirring is maintained, which speeds up the process and conforms homogeneity. This is absent for hydrothermal reactions.

4. Very often, coating agents are used for surface functionalization in solvothermal reactions. This can further decelerate the growth of seed crystals.

Which is your material? A Li rich cathode is too generic...in this field no right ratio of intensities exist, in many cases these materials could also present preferred orientation effects.

Here are some suggestions:

EBOOK (PDF) ISBN978-1-83881-088-7

DOI: 10.1039/D0MA00807A

· DOI: · 10.1007/978-3-030-36260-7_1

Hi there,

We provide researchers with low-cost mild- and hard- anodized AAO templates, having different pore lengths and diameters. Contact: amirh.montazer@gmail.com

Esteban Diaz-Torres Wow , great explanation.

Thank you my friend !, Yo soy de Monterrey,

Saludos !

Quantum confinement effect is the main reason. Quantum size effects result from reduction in the dimensionality of the material below a certain initial value that leads to changes in the electronic structure. So optical and structural properties are get changed.

In addition to previous answer, the use of super hydrophobic surfaces in solar would help you prevent the surface being dirt, which results no need of cleaning. So, it is equally important to make them hydrophobic too.

Very interesting @Hassan Yousefnia, is that bio-degradable or bio-based materials? What is the source of polymer? Oil-based, plant, or bacteria-enzyme? As for the application, are you aiming for mechanical properties or functional such as anti-oxidant, gas barrier, perfume and so on?

Dear all, solubility depends on the chemical structure and types of existing intermolecular forces. Excessive sonication may degrade any of the compounds present in the recipe. There are many techniques to solubilize poorly soluble drugs. Please check the following links. My Regards

The nanostructures may scatter light if their optical size is comparable to the wavelength of light, if that's what you mean.

Using a retroreflector with low angular tolerance (<5 arcsec) is very important to make sure that the spatial overlap between the pump and probe beams is always ensured with very high precision once the delay stage moves. There are multiple samples with known transient absorption results in the literature such as graphite, gold nanoparticles, etc. I suggest that you run some measurements on one of these samples and compare to the literature to make sure your setup is working properly. However, the main measure to make sure that your setup is working properly is to measure the beam profile and pulse duration right before your sample. Not using the right optics could lead to spatial-frequency beam perturbation and/or stretching the pulse duration.

Dear Sir

Please check the following link which me be useful to you

Cory Jensen , Thank you!, I appreciate it.

Regards,

I prepared nanostructured Silicon from Silica nanoparticles because of its low cost fabrication. But methods like this can't produce amorphous silicon.

@ Martin Muller

caLAm

actually, strong acids are not necessary to produce normal blue fluorescent C dots. the main reason for using strong acids and bases or trying new precursors is to improve QY and photo-stability or engineering the emitted and adsorbed light to reach the NIR region. to achieve this goal it is needed to work on the C dot inner structure.

I am working on the same area and I found this recently published review paper amazingly useful, all recent studies are summarized and very good mechanism explanations are gathered. hope you can use this article to understand the mechanism better.

Hi Selva,

You can get ideas of sample crystallinity (single crystalline or monocrystalline) and different planes from SAED patterns of your samples.

1. Single continuous ring indicating amorphous materials, whereas dotted ring indicating single crystalline materials

2. To find out the different planes, you need calculate radius (R) of each ring from your SAED patterns. Ring diameter = 2R and Radius = R/2. So, Inverse of R is d-spacing values. Each plane has different d-spacing value. So, matching d-spacing from your SAED patterns and d-spacing values from literatures, you can identify which ring indicates what plane. Generally, bigger ring means smaller d-spacing values, so plane shows up in higher 2-theta in XRD patterns.

Though I am not quite sure about the their relation, these following paper might help you -

Yetkin Şen :

I believe what you are referring is to the nanostructure of these kind of bulk materials (so called conventional TE materials).

If so, you aren't going into the wrong direction...

Modifying the nano & micro structure of these bulk materials is one of the strategies that has been followed to increase the ZT, and has given good results in many cases (ZT up to values of ~1.5).

These ideas are not new at all, so there are a lot of works studying different ways to nanostructure these type of bulk materials, which to beging with, should be structured as polycrystals (is important to have high density of grain boundaries)...

These ideas have more than 20 years and began precisely with Bi2Te3 and Sb2Te3 based alloys.

One of the ways to do this is with what I believe you are trying to say with "suitable composite materials", since some of the techniques involving working with the nanostructure involve adding nanoparticles of different nature, as metallic nps or metal oxides, e.g. Cu nps, ZnO, Al2O3, etc... or other nanostructures from metals as Bi or others...

But in the end, It has n't seen to work as well as with Carbon nanostructures.

Nowadays there has been many studies with Carbon nanostructures like: Graphene and Graphite nanoplatelets, CNTs , Graphene Oxide, even C60 molecules ...

There are many studies regarding this topic, and several variations regarding the sites in the bulk structure where these nanostructures need to be placed (as in a matrix with embedded nanoparticles), also the Grain Boundaries play an important role in these materials

Anyways I will recommend you still to continue on the line of the bulk conventional TE materials, like the ones already mentioned above, but try to look up for these kind of studies of a nanostructure modification approach ...

There is another totally different approach along the lines of Quantum materials (as Quantum Wires or Quantum Dots, etc), but that is another different approach, where now the main problem you have is the high fabrication cost..

Let me see if I can find a general reference for you to attach here ...

Best Regards ! :)

The following is a good reference: a paper review-kind of nanostructured bulk TE materials

Hi,

The grain size may influence the biocompatibility, so the alloys co-exist better with human tissue. Also, strength is always important for the implants. SPD may give rise to better properties on those aspects.

You can follow

Journal of Applied Physics, Volume 111, Issue 12, pp. 123714-123714-6 (2012)

Both options suggested by Dr. Mercier are great. I personally use ImageJ as well and there are few guidelines and instructions online. I have also encountered some publications in which people have carried our porosity measurements from images by microscopes built in software such as Leica.

Dear Mahdi Hashemi,

you know that the equation which is involved in the Williamsen-Hall plot approach converts into the Scherrer equation when the internal stress is set to zero.

So when having more than one peak of a phase it is advised to use the Williamsen-Hall plot approach because peak broadening due to stress is here adequately considered when evaluating the crystallite size.

In the case of having only one peak available you have no other chance than using the Scherrer equation. But the result can be affected by residual stress.

Final remark; in the equation involved in the Williamsen-Hall plot and Scherrer equation the crystallite size shows up; not the grain size.

Instead of (current) i vs. V_r (scan rate) you could plot (Capacitance) C vs V_r.

A CV (Cyclic Voltammetry) regime having a pure Capacitive origin converges to a limiting value C_pureCap, a constant Capacitance value (C_pureCap).

So, you can consider the i_high (current) inside this V_r-regime, as a pure Capacitive current ( i_high~i_pureCap) for your target, e.g. calculate, only, the Capacitive (component of the) current density, from your curves' set of the exp. CV(s).

Thank You @ Muhammad Abbas,

If you have any review/research articles related to this matter pls suggest.

Both answer from Sorcar and Li are recommended but mo simpler explanation is by adding S ions to ZnO will create a case just like solid solution from ZnO-ZnS but with small portion of the second and since optical energy gap for ZnS is smaller then absorption peaks due to the new cobination will go to a lower energy

for mor details you can read articles on the optical properties binary compound solid solutions

Dear Rassoul,

There are relatively few organic solvents that will freeze dry well - DiMethyl Acetamide is not one of them! It may be used for inks, but not freeze drying. Things like tert butanol, water, 1,4-dioxane, cyclohexane freeze dry well. DMSO can be used, but the risk here is having a suitable system for working with agressive organic solvents is the challenge (this is also true for DMAc.) as most dryers are made for water ...

To disperse the carbon black you will need a whetting agent in there, and you need to generate some viscosity in the mix to help it disperse well using a high sheer mixer. It is unlikely from my ancient knowledge of whetting agents (I'm not up to date) that these will not evaporate but will remain behind in the carbon black. Typically carbon black is dispersed into oils, not things that freeze dry well.

Do you really need to freeze dry? Is this the correct process?

Kind regards

Rob

I recommend the answer by K. Sreenvias

since the subject is almost prehistoric

Dear P. Seenuvasaperumal

Greeting

Self-plagiarism simply means that you write a sentence, phrase, figure, data or any other thing from your published work in another work as it is even you cited the old work. So you must not take a paste and a copy from the old to the new, but you should reformulate what you want to mention in the new work. Otherwise, you can cite the old work and write the sentence:

as mentioned in a previous work [REf.].

Good luck

try opt ur molecule with b3lyp/lanl2dz, b3pldz/lanl2dz,pbepbe/lanl2dz combos they r suitable for opt 3d transition metals. i hope ur query is solved. if not i can furthur suggest u basis set combinations.

Thanks Prof. Yuri Mirgorod for your answer.

Dear Khalidah Al-Mayalee,

Please go through my papers and I certainly hope you will be alble to get the answer.

Regards

Typically thiols in proteins are internal and very few. Since carboxylic and amine groups are on the surface of the protein, much more and also interact with gold they might be more likely to react with the surface. Naturally there is also the disulfite bridge issue. 

Yes Dr. Nadir you can use this effect to explain the widening of the energy gap for special material such as TCO transparent conducting oxides (CdO,ZnO, SnO2 , In2O3  and other materials like CdS InSb etc.....) and in the case of highly dopant concentration where the lower states of the conduction band will be occupied by the excess carriers (electrons) from the impurities atoms, therefore the electron need additional energy to promote from valence band to empty state in the conduction band.

The attached papers enhance the B-M effect.

1. page 56 . 

2. page  6 or 38 .

Also the widening of the energy gap ( blue shift of the absorption edge) can be attribuited to several reasons : 

The blue shift in the band gaps observed for the films may be explained by severalmechanisms such as (i) Moss-Burstein effect which originates from the lifting of Fermi level into the conduction band due tothe increase in charge carrier concentration; (ii) the decrease in shallow-level trap concentration near the conduction band resulting from the improved crystallinity, and(iii) reduction of band bending effect at the grain boundaries. In nanocrystalline materials band bending effect takes place atgrain boundaries due to their increased surface to volume ratio. For smaller grains, the band bending effect is large whereasit becomes flatter for larger grains. as in the paper 3 page 5. 

Best regards.

Dear Mrs. Lungu,

I am presently not active in the field but believe, to have some background in it. I have worked earlier on transmission and reflection on thin films and thermal emissivity. 

The 1st thing to look at is, are the nanoparticles stable under all wavelength conditions: For AgNPs I would there not be so sure (think of old photographic film) for short wavelengths.

On the other hand, one thing to look at is also: In what kind of liquid or matrix are the nanoparticles insereted or are they pure? In the latter case, you may disregard this point, in the other cases you may make sure, the TiO2NPs have no light catalytic effect on the liquid or matrix material, since this would also alter your optical properties.

I am not sure, whether or not my comments are of help but this is, what I can say in short, perhaps you can leave me a note on that, no matter how it looks!

with best regards

Johannes Weiss

You may refer to the following articles:

I think the width of the ribbon is not so large that the band of one edge is affected by the other.

Dear Deepinder,

It seems there is some physico-chemical interaction between your drug and the lipid used for preparation of nano-structured lipid carriers.

I think you should study this interaction first through performing some experiments for example DSC, XRD or FTIR  which suits your drug and polymer structures.

The bigger size of your blank NLCs compared to your loaded NLCs  also the unstable freeze-dried product might confirm my assumption.

I totally agree with previous replies offered by other colleges regarding changing the preparation conditions.  

I have been somewhat involved in some of the discussions and out comes

“How Adverse Outcome Pathways Can Aid the Development and Use of Computational Prediction Models for Regulatory Toxicology”,

Clemens Wittwehr, Hristo Aladjov, Gerald Ankley, Hugh J. Byrne, Joop de Knecht, Elmar Heinzle, Günter Klambauer, Brigitte Landesmann, Mirjam Luijten, Cameron MacKay, Gavin Maxwell, M.E. (Bette) Meek, Alicia Paini, Edward Perkins, Tomasz Sobanski, Dan Villeneuve, Katrina M. Waters, and Maurice Whelan,

Toxicological Sciences, accepted September (2016)

“The bio-nano-interface in predicting nanoparticle fate and behaviour in living organisms: towards grouping and categorising nanomaterials and ensuring nanosafety by design”,

Iseult Lynch, Arti Ahluwalia, Diana Boraschi, Hugh J. Byrne, Bengt Fadeel, Peter Gehr, Arno C. Gutleb, Michaela Kendall, Manthos G. Papadopoulos,

BioNanoMaterials. 14, 195–216 (2013)

“Concern-driven integrated toxicity testing strategies for nanomaterials - Report of the NanoSafety Cluster Working Group 10”,

Agnes Oomen, Peter Bos, Teresa Fernandes, Kerstin Hund-Rinke, Diana Boraschi, Hugh J. Byrne, Karin Aschberger, Stefania Gottardo, Frank von der Kammer, Dana Kühnel, Danail Hristozov, Antonio Marcomini, Lucia Migliore, Janeck Scott-Fordsmand, Peter Wick and Robert Landsiedel,

NanoToxicology, 8, 334-338 (2014)

“Minimal analytical characterization of engineered nanomaterials needed for hazard assessment in biological matrices”,

Hans Bouwmeester, Iseult Lynch, Hans J. P. Marvin, Kenneth A. Dawson, Markus Berges, Diane Braguer, Hugh J. Byrne, Alan Casey, Gordon Chambers, Martin J. D. Clift, Giuliano Elia, Teresa F. Fernandes, Lise B. Fjellsbo, Peter Hatto, Lucienne Juillerat, Christoph Klein, Wolfgang G. Kreyling, Carmen Nickel, Michael Riediker, Vicki Stone,

Nanotoxicology, 5, 1-11 (2011)

I don't have a model, only empirical testing to determine the optimum cutter, feeds and speeds, much like Senol Bayraktar did in the paper attached to his (her?) reply. I recommend that you perform empirical testing. It does not require large panels to do this. We investigated both hole drilling and edge trimming for FMCs (I am sorry, I cannot be more specific, nor can I share our data).

Rayleigh scattering is only for small particles typically r < lambda/10 where lambda is the wavelength of incident light. Most TiO₂'s have sizes in the optimum range for scattering in the 300 nm region (into the Mie region) where Qext approaches 5 (use Phlip Laven;s excellent MiePlot program to show this).  Blue light has higher energy than red light and Is thus more easily scattered (1/lambda⁴ dependence in the Rayleigh region).  Plus there's an absorption band for TiO₂ (depending on the form - rutile or anatase) below 420 nm or so  -that's why it's used as a UV sunblock.  For more diversion see:

August 11th 2011 Optical properties of the three forms of titanium dioxide

So both scattering and absorption can be factors.

For a scientific aim, plz see the attached file below, and keep in touch

nano Ag particles has 3 peak in XRD spectrum.

peak about 38 degree is (111); that it's more intensive than the other peak about 44 degree(200) & 64 degree(220).

nano Ag particles in this spectrum  has a FCC structure.

donot remove ligand, excange them

use for example S2-, dilute Na2S in DMF (0.1-0.5% in weight) , mix this solution with the QD in hexane and sonicate to induce phase transfer

trash the clear part and save the polar part, readd hexane to fusrther clear, the polar part and once settle remove it

trhen add ethanol to precipiate the particle, centrifuge and redispersed the fomed pellet in DMF

alternatively solid state ligand exchange work well, dip for 1min a film of QD in short ligand solution (EDT, S2-, Cl-) in ethnaol a,d then rince in pure ethanol

Dear,

Capping agents cover the refine surface of nanoparticles and prevent them from coagulation or aggregation. For metal oxide use CTAB or Twin 80 as surfactant.

You can do the hall effect measurement (4 probe Vander Pauw technique) or else can check the Seebeck coefficient.

The sign will tell you about the majority carrier type.

You may want to bookmark error.wiki for this kind of thing.

I've been dealing with modification of nanoparticles to increase their hydrophilicity for almost 10 years. In the case of CNTs, you can impart oxygen/amino moieties either by wet chemistry approaches (e.g. strong acid treatments, p-p stacking with aromatic compounds containing even hydrophilic moieties) or dry chemistry, by using plasma reactions. Read this article:

Likely it not exactly what you are looking for but I suggest you visit the following sited on twins http://www.crystallography.fr/mathcryst/twins.htm

Drift of a nanoindentation instrument may also depend on the type of Instrument you use. E.g. we have a Hysitron Triboscope where the indentation tip is attached to an piezo-scanner for imaging purposes and the piezo show creep behavior after changing position of the tip. The only possibility to avoid this is to make a pause before each new indent to let the piezo creep finish (typically 3-5min).

Beside that a housing of the Instrument is essential to avoid thermal changing and a sufficient long thermalization time is nessecary after closing the housing and before starting measurement. That can take a whole night (or day) to wait.

Beside that , naturally,  some materials themselves show creep, especially soft metals. This is the normal plastic behavior of these materials and has to be considered in the measurement, so measurement time has to be (in contrast to what Jonas Paul wrote) long enough to consider material creep, otherwise hardness measured will be too high.

Finally, each nanoindentation should include a drift measurement and a off-line (or on-line) drift correction which will minimize the drift effects.

Best regards

Kirsten

Hi,  and thanks a lot Jules. What I am attempting is to cover some pyramidal microstructures covered in thin oxide, and then expose the tip for etching away the oxide and do metallization. It seems that 130 C in a convection oven for 30 minutes does the job with a pretty thin resist, close to what you suggested.

Hi  Piyush,

no normally it is not possible to do such Thing due to the corrosion of the steel. Aluminium is used due to the protection layer (in other case at the positive would be used also copper).

Best regards

Michael

I think you can try with AFM and nanoindentation. They both can work on this scale. However, for nanoindentation, to get indent on this thickness, you may have to have a good optical system accompanying the nanoindenter.

What kind of mechanical properties are you trying to get? Nanoindentation can provide you Young's modulus and hardness. And to some extent, you can predict the yield strength and strain hardening exponent.

If you want to know the interfacial strength of the interface, then something like the lap-shear test or peel test may help you.

Good luck!!

Thank you for your clarification Andrei. I have sometimes used "sputtering" and "dry etching" rather interchangeably when referring to Ar ion surface cleaning, but it's probably better to stick to "sputtering".

Dear Chandrasekhar

                                    N719 dye adsorption  can  be  quantitatively determined from the UV-Visible spectroscopic measurements  by monitoring the absorbance at or near

510 nm (probable abs. max.) . First prepare 10ml  N719 dye solution in 0.1 M NaOH and note its absorbance max. Determine the absorbance of  adsorbed dye from the desorbed dye solution obtained by dipping dye coated TiO2 film in 10 mL 0.1 M NaOH solution for 10 minutes. Then subtract the concentration to find the quantity of dye adsorbed. Use formula A= ECX...

Dear Karthik, 

Thank you very much for your answer. Do you know any paper or source I can use as a reference for this affirmation?

Dear Ujjwal,

From the principle point of view, the luminescence decay depends on the recombination rate of the excess charges produced by input photo excitation. The time constant of the radiation decay process is the lifetime of excess carriers in the material.

If the lifetime is constant then the rate of decay will be constant irrespective of the excitation level. However this is not the case in many materials. The lifetime may decrease with the increase in the excess electron hole pairs and this may be the case which you report upon. So, if the decay rate decreases appreciably it may result in smaller total decay time.

In summary, the decay rate is controlled by the lifetime of excess electron hole pairs which may depend on the excess charge concentration level.

wish you success 

The band gap reduction is caused by the less electronegativity ofr nitrogen faced to oxygen conteparts

Looks like there are several rules to follow. The first one I think is micro-segregation. Charge neutrality is another. I'm not sure how chirality and close-packing play in this situation.

I agree with Dr. Yu. Ivanisenko completely.

You will need to calculate number of cells and nanoparticles because efficacy (and toxicity) of nanoparticles is influenced by number of nanoparticles internalized. Please see following for guidance:

1.         Soenen SJ, De Cuyper M. Assessing iron oxide nanoparticle toxicity in vitro: current status and future prospects. Nanomedicine. 2010;5(8):1261-75.

2.         Soenen SJ, Rivera-Gil P, Montenegro J-M, Parak WJ, De Smedt SC, Braeckmans K. Cellular toxicity of inorganic nanoparticles: common aspects and guidelines for improved nanotoxicity evaluation. Nano Today. 2011;6(5):446-65.

you can disperse your nanosructures into a solvent, like water or enthanol, then using the blank solvent as refference, you will get the absorbance or transmittance UV-VIS Spectrum as you want.

graphitic carbon nitride as an efficient with lewis base functional group(electron pair donor) and chitosan as sn efficient lewis acid (electron pair acceptor).  A probable mode to develop interaction between chitosan and graphitic carbon nitride is lewis base-acid interaction. 

Spatially discretise the K-S PDE in space using 'holistic discretisation' (that has very good performance for nonlinear systems) via my web service at http://www.maths.adelaide.edu.au/anthony.roberts/holistic1.php

Then integrate the spatial discrtisation in time using Matlab ode15s or Octave lsode routines.

Dear Hou,

Your question is an interesting for solar cells construction. It concern's the thickness of the active layer. 

Adding to what has been said  by he colleagues above, the thickness of the active layer is primarily determined by the absorption coefficient apha such that the thickness d must be greater equal than the inverse of the absorption coefficients, d=> 1/alpha. The other important factor determining the thickness d is the diffusion length L of the minority carriers of charge carriers on both sides of the junction. It is so that d must be => the sum of the minority carriers in both sides of the junction plus the thickness of the space charge region.  But it must be said that the primary limiter  is the effective absorption depth 1/ alpha. Then one must take care of the diffusion lengths to make  them greater equal this depth. This is accomplished by  adjusting the minority carrier lifetime in the material. In some new materials one can not enhance the lifetime of minority carriers or the generated excitons beyond an upper bound which may be smaller than the absorption depth in this case the the material thickness d is limited by the diffusion depth.

For more information about the construction of solar cells and their internal physical and technological parameters please see the link:https://www.researchgate.net/publication/236002879_A_course_on_photo-voltaic_array_systems

wish you success

Hi...Mohamed, In fact you can find in various journals'  articles concerning Gold (Bulk and Nanoparticles). The size , of course is so different. You can see from SEM/TEM data Au-spherical nanoparticles and also from UV-Vis spectroscopy (a shift - red). 

Regarding crystal structure for bulk and NP's Au, it is clear stated that the nanoparticles possess a well-defined atomic arrangement resembling the face-centered cubic (fcc) structure occurring with bulk gold. The fcc-type features of this arrangement become more prominent with increasing nano-particle size (see ref : Valeri Petkov, Yong Peng, Geoff Williams, Baohua Huang, Donald Tomalia, and Yang Ren

Phys. Rev. B 72, 195402 – Published 3 November 2005).  In my opinion, the difference which is appeared is the FWHM (representative peaks of XRD pattern) of both bulk and NPs' Au.  Hope this will be useful.

Rudy Situmeang

Hello,

The use of fibers as reinforcing agents depends mostly on the intended applications.

For example, natural fibers like jute, hemp, sisal, etc. or CNTs, are mostly used as reinforcing agents to improve the mechanical properties of a polymer (Construction materials, light weight body parts for automobiles). Extensive work has been carried out in the same field. 

The incorporation of bio-char, clay or metal nanoparticles into a polymer also reinforce the matrix.  Most exploited applications include adsorbent materials/ antibacterial agents/ flame retardants, etc. Hope the articles will help you 

Normally the pressure boundary condition at the outlet of a fully developed channel is given by prescribing a constant normal stress at the outlet  i.e. -p + 2*mu* du/dx = Constt. The constant could be Zero as well. And in non-dimensional form the, the BC would be. –p + 2/Re*du/dx = 0 where Re = HU/nu and H is the height of the channel. Since the flow is fully developed, du/dx = 0, So the pressure p = 0 at the outflow. So should you try dp/dx = 0???  (see the ref. below).

Gartling, D, “ A test problem for outflow boundary conditions – flow over a backward facing step”, International Journal for Numerical Methods in Fluids, V11, pp 953 – 967, 1990. 

Based on our results we are not able to tell anything about the solubility. There is probably some rearrangement of the metals of bimetallic nanoparticles, but this effect has been thoroughly studied in previous researches. See for example, M. Lukaszewski, A. Czerwinski, Electrochim. Acta 48, 2435 (2003); J.S. Jirkovsky, I. Panas, S. Romani, E. Ahlberg, D.J. Schiffrin, J. Phys. Chem. Lett. 3, 315 (2012). In both papers it is demonstrated that by changing the electrochemical conditions the surface of the material can be enriched with Pd or Au.

Normally you would spray the power to form a solid and then do microstructure.  However your question seems to indicate that you want to look at the metallurgy of the powder before applying heat during spraying.  If this is the case then use a strip of nickel as a substrate to place the powder on, then carefully immerse it in a solution of electrolysis nickel and plate nickel on the substrate and the powder.  This should consolidate and bond the powder such that it can be sectioned, mounted and polished for etching, then studied in the SEM.  Do the grinding and polishing as if it were ceramic, Buehler Diamet system.  If your powder is very small, you will need about 40,000 x magnification.

For etching go to the books by either  Kehl or VanderVoort for etching solutions and procedures.

Note the above technique must be done carefully as heating the electrolysis solution too vigorously will disturb the powder, do it by heating slowly until the powder is securely bonded onto the substrate, then raise the temperature to thicken the nickel coating.

If you want to encapsulate your particles with silica, I recommend a microemulsion method. It is very robust and works with almost any type of nanoparticles. Enclosed are two examples, but we did this with many other types as well (just have a look at my publications list).

If you are particular about electrodeposition non-conductive surface, you have  to make surface conductivey by chemical method like stannous chloride treatment and followed by AgNO3 treatment or other you have to depend on chemical or physical vapor deposition

OK I will take in consideration these suggetions, it is helpful. Thanks.

From the point view of NDT, If the grain changes could make differences in the electrical conductivity or magnetic permeability, you could test eddy current, but you will need prepare special specimens for the calibration.

You may also consider coating your substrates with low-fouling materials, such as PEG and dextran. This kind of setup could allow you to use complex media such as serum-containing ones.