SEM/EDX - Science topic

EDX analyses the characteristic X-rays coming from the sample surface. In samples coated with gold, gold peaks may appear in the spectrum, since the characteristic X-rays of the gold itself will also be detected. This can complicate the spectral analysis of the sample material and lead to incorrect results. If the coating is too thick, it can weaken the signals from the sample material underneath and the signals from the coating alone may dominate. This prevents the sample from being analysed correctly. Alternatively, other coating materials such as carbon can be used to overcome the problem of insulating properties, since carbon has a lesser effect on the EDX spectrum than gold.

What does this image show?

A dark powder on a bright uneven surface?

Which of the spectra were taken on this surface?

May be you'll find this useful:

Preparation of biological specimens for EDS with an SEM

​https://www.oxinst.com/blogs/preparation-of-biological-specimens-for-eds-with-an-sem

Tips and Tricks for Biological EDS

Advanced techniques in SEM and EDS for biological samples​https://www.selectscience.net/expert-insight/advanced-techniques-in-sem-and-eds-for-biological-samples/?artID=56957

Dear Katrina Skerratt-Love ,

the evaluation of XRD pattern of amorphous material is is a challenge because it mainly consist of a large broad hump which some times is more or less structured by one or two shoulders. From that perspective you already see, that there is much less information available compared to a 'crystalline' XRD pattern.

In order to compensate the lack of information a bit one uses the small angle scattering technique, the experimental set up of which is in principle similar to an XRD one. The difference is the 'theta' or '2theta' range combined with the wavelength in use. Here the physical parameter known as the magnitude of the momentum transfer vector show up.

Details about the evaluation of such 'amorphous' pattern you will find for example in:

Tutorial on pairdistribution function:

I admit, that it a hard job to dive deeper into this subject...

Good luck and

best regards

G.M.

you could type "What material is used in dental 3D printing?" in google or google scholar for information to a wide array of materials used depending the desired result. for example teeth use different material than tissue regeneration.

if possible send your sample to India

As per the images, that can be almost any hard resin. Impurities are mainly mechanical inclusions (except for NaCl), which are also typical for this material.

The information I see on these images: brittle chips with no soft whiskers (that means the material is fully polymerized and hard under given conditions), and some inner structure (globules of 300-400nm).

I would recommend getting ATR-IR or Raman spectra for the material and checking the database for a match. PXRD may also help, but that's more expensive, longer and not really suites the task.

Nikhil Verma

In XРS ( X-ray photoelectron spectroscopy) measures the binding energy of electrons with a nucleus when irradiated with monochromatic radiation, which appear as a result of the photoelectric effect.

Scanning electron microscope (SEM). The incident electrons interact with the atoms in the sample, creating various signals that contain information about the surface topography and composition of the sample. The electron beam is scanned as a bitmap and the position of the beam is combined with the intensity of the detected signal to produce an image.

Energy dispersive X-ray spectroscopy(EDX). The electron beam is focused on the sample and transfers electrons from one shell to another. This releases X-rays. The amount and energy of the x-rays emitted by the sample can be measured using an energy dispersive spectrometer. Since the energies of X-rays characterize the difference in energy between the two shells and the atomic structure of the emitting element, EDS makes it possible to measure the elemental composition of the sample.

XRD identification of materials based on their diffraction pattern. The sample is irradiated with X-rays and the intensity of the rays leaving the sample is measured depending on the angles of the crystal lattice.

Well, oxygen enters sputtered films usually via the chamber residual gases.

You can use SEM/EDS to check for homogeneity of Si distribution. If you expect non homogeneity on 1-100 micron scale, you may want to use line scans of Si radiation (maps are not as sencitive). If scale is in range of millimeters or cantimeters, you may want to perform spot analisis for a lot of spots or use not a micro analytical technique, like XRD.

Hi Dear Daniel Guerrero

I recommend listing all indications of Hot cracking so you can separate them easily.

According to J.C. Lippold's welding metallurgy book: DDC are formed in materials with FCC crystal structure along MGBs.

I want to emphasize on MGBs (Migrated grain boundaries). DDC is always formed along MGBs.

It is one of the ways to identify.

a good article about MGBs: researchgate.net/publication/364226201_Migration_of_solidification_grain_boundaries_and_prediction

Best regards

With EDX you can collect the spectrum of your sample and obtain a table with the amount of the elements expressed in weight percent and atomic percent. So it is simple to calculate the ratio beteween some of them

Tq for your sharing

I would usually start with a thermal camera for mapping purposes..Then mount the thermohygrograph data logger on the bluish areas.

I assume that the EDS analysis was done over the area of the SEM images shown and the concentrations were obtained by pressing the “QUANT” button of the software.

The spatial resolution of EDS (laterally and in depth) is given by the beam-sample interaction (i.e. beam energy, atomic number, density) and the physics of X-ray emission.

A frequently used estimate is the Kanaya-Okayama range (K Kanaya and S Okayama, J. Phys. D: Appl. Phys. 5(1972) 43-58, DOI: 10.1088/0022-3727/5/1/308).

For pure Fe and 15 keV electrons the electron excitation range is ca. 1 µm, the size of the volume where the X-rays are from is ca. 0.7 µm for Fe K radiation.

EDS quantification assumes that the sample is sample is homogeneous, flat, and thick (compared to the excitation range).

See here: https://www.youtube.com/watch?v=et9CTYHUoos&app=desktop

This presentation by Dr. Jens Rafaelsen was recorded on the EDAX booth at M&M 2018

At 35:45 “If your sample doesn't meet those requirements: don't click the QUANT button: You'll get numbers, they'll be garbage!”

The “Fe-before” sample is likely Fe with a native iron oxide.

Is the sample flat? Is the sample homogeneous (laterally and in depth)? Is the oxide thick?

If the iron oxide is thin (< 0.7 µm), the volume you analyse is composed of iron oxide(s) + iron metal. The prerequisites of the quantification model are not fulfilled.

The “Fe-after” sample is likely Fe with thick iron oxide(s).

Is the sample flat? Is the sample homogeneous (laterally and in depth)?

The prerequisites of the quantification model are not fulfilled.

Is the oxide thick?

If the iron oxide is thick (> 1 µm), the volume you analyse might be composed of the iron oxide(s) formed, but the prerequisites of the quantification model are not fulfilled.

As mentioned by Vladimir Dusevich the EDS spectra should be evaluated carefully. There are small peaks around 2 keV. For “Fe-before” at < 2 keV, for “Fe-after” at ca. 2.3 keV. What’s this?

> Also, I have some questions about SEM-EDX:

Your questions 1-5 are not directly related to EDX.

The chemistry of oxidation of iron (and steels) in aqueous solutions has been studied for decades because of the importance for corrosion and power generation and the results are now textbook knowledge.

I guess for electrolysis a lot of actual work can be found.

For thicker oxides scales composed of different oxides may form. Here, preparation and analysis of cross sections may give more insight.

Preparation methods and analysis will depend on the thickness and stability of the scales (fracturing, preparation of cross section by metallographic methods, FIB cuts; EDS in SEM or TEM?)

If you have a cells monolayer, 30 min is a good time. If you have something like a tissue developing, with a lot of collagen, then you need 1 hr. HA is soluble in water (very slow, but still...). So if you culture started generate small centers of mineralization, you do not want to keep it too long (days, weeks) in water solutions. From the other side prolonged storage in desiccator can lead to fungus growth. Some desiccators are badly infested with fungus and need through cleaning and disinfection. From my opinion the best way to store specimens is when their preparation is complete, i.e. they are dehydrated and coated with conductive coating.

SEM based EDX is very simple to do and does not require a hard core methodology for simple analyses (ie., what is present). Accurate “quantification” requires a more involved methodology.

There are other fast turn-around methods for rapid analyses Including ICP and XRF. ICP is likely the most accurate method of all the elemental analyses, EDX is most sensitive to the lighter elements, while XRF is most sensitive to the heavier elements and can be done with independent instrumentation, or with SEM associated instrumentation. All can be used to answer the simple question of what is present, but all can also be used for the more involved question of methods of quantification.

Dear Alireza Karimi Yes I agree with you that XRD with micron size X-ray beam called as micro XRD can be done on a different positions with 2D X-ray can give the actual micron size phase formation details.

your question is not clear

please give us more clarification

Hi Joana,

I am not 100% sure what questions you are asking but if you are interested to compare the effects of ocean acidification (i.e., lower pH) on coral skeletons you have some options. Looking and comparing basic skeletal corallite structures at macro-morphological (e.g., corallite diameter and wall thickness; septal and costoseptal thickness and high) and micro-morphological levels (e.g., septal teeth height) would be relatively easy. You can look at the thickness and porosity of the skeletal material in general. Recently new studies have been done on pH effects on crystallographic features of coral skeletons (see attached paper). I hope the attached papers will assist you in getting your answer, the reference sections are full of good papers.

Cheers,

Tom

By chance, I just had the inverse problem: I tried to find very small traces of Au, hoping for Au M-alpha at 2.123 keV (see Dirk's answer). This is, in the low energy range at least, the most intense EDX peak from Au. Indeed, I first had to make sure that my sample was totally free of P (2.139 keV). There are also some other elements (metals) that could be problematic.

Btw, EDX works very nicely with ESEM, so I usually leave my samples totally untreated, and image them in 100 Pa (or more) of water vapour. If you have no ESEM option, and you need no imaging, you, too, could try without coating, as suggested by Dirk.

One more point, which you might know already: Never *ever* trust your EDX % for C and O. You will always either deposit or remove carbon, and often also oxygen. I would guess you are interested in the P/O ratio. If so, you can test this with EDX of a well-defined sample of a stable phosphate, under exactly the same conditions that you use for your sample.

Dear K. R. Jaliya Manuda ,

let me first summarize some facts:

i) 'thin' film containing sulfur (S) on top of gold (Au) layer

ii) S containing film:

S K-edge: 2,47keV

S fluorescence lines:

S K-alpha: 2,3keV

S K-beta: 2,46keV

iii) Au substrate:

among others;

Au M_IIIedge: 2,74keV

Au fluorescence lines:

Au M_IIIN_IV: 2,39keV

Au M_IIIN_V: 2,41keV

Data were taken from J. A. Bearden tables:

https://journals.aps.org/rmp/abstract/10.1103/RevModPhys.39.78

conclusions:

a) The energy position of the S K-beta line is about 50eV above the Au M_IIIN_V line; but due to the limited energy resolution of the detector (assumed to be about 120eV) S K-beta will not be seen in the presence Au M_IIIN_V.

b) The energy position of the S K-alpha line is about 90eV below the Au M_IIIN_IV line; but due to the limited energy resolution of the detector (assumed to be about 120eV) will not be clearly seen in the presence Au M_IIIN_V.

c) thus the Au lines have to be omitted or extremely minimized.

There are two ways to do this.

i) avoiding, that excitation radiation will reach the Au stubstrate

and/or

ii) reduce the excitation energy to below Au M_III-edge energy.

XRF scenario:

In the case of XRF, you have to have x-ray photon excitation energies of above the K-edge energy of sulfur, which is at about 2,47keV. For a significant fluorescence yield you have to go to x-ray tube voltages of well avove 2,47kV, at least some 100V above. However, for the maximum photon energies of such an x-ray spectrum you will have penetration depths in the very low µm regime; thus the x-rays will also hit the Au layer beneath your thin film and will be able to excite the Au M_III core level, when the energies are above 2,74 keV.

SEM-EDX scenario:

In the case of electron excitation one will have sub micron penetration depths for the whole electron scatter cascade, when you deal with quite low primary electron energies^*). The penetration depths of the primary electrons of such a beam is much smaller.

So there is a chance, that you will have only a small fraction of primary electrons, which will be able reach the Au substrate.

If one in addiiton restricts the electron beam voltage to below 2,74keV; there is no possibility to excite the Au M_III fluorescence.

Final conclusion:

a) XRF is, to my opinion, not suitable here, due to the strong S- and Au-peak overlap.

b) SEM-EDX may work, if the electron acceleration voltage is restricted to below 2.74kV (but well above 2,47kV).

*) https://www.globalsino.com/EM/page4795.html

Good luck an

best regards

G.M.

It's not 100% clear to me what you are doing. Do I interpret correctly that you made an electrode out of brass, used it in an electrochemical device for 24h and then analyzed it in SEM/EDX?

In that case the 24h is probably a convention within your community in order to get publications which investigate the aging of the electrode to be comparable. People could probably have chosen a different time frame, but multiples of 24h are, of course, well-plannable and -executable time frames.

Thanks, Marcella Bini,

We performed a single-crystal x-ray experiment. It is certainly a homogeneous compound with a defined structure, however, it still can be non-stoichiometric

Try repolishing, by a 1 micron diamon you should get a mirror surface, also try using Nital ( 90% metilic alcohol in 10% nitric acid).

It definitely looks like some organic contamination. Was cooling liquid applied when sectioning? Was specimen polished after sectioning?

The thread that Sourav Roy recommended will get you the answer you need.

In summary of the thread: XRD measures crystallite size which is inherently different from particle size as measured by SEM. In general, particles are multi-crystalline (i.e. having multiple diffracting crystallites) which XRD inherently measures.

Good luck.

You need to repeat your analysis. There are lines on your spectrum (possible O and Si) that were not taken in account. It looks like Pb alaysis was performed on M lines, which are overlapping with Si line. You need use L lines, but then it's better to repeat X-ray acquisition at 20 kV. Without using L lines it's mostly impossible to say if presence of S is real and not an artefact produced by software. And if you were using standardless analysis (and I am sure you were), then results for C (and O) are mostly useless.

The best practical resolution in FE-SEM usually can be reached at accelerating voltage of about 1-3 kV. Higher voltage just increases the interaction volume via increasing the depth of electrons penetration into the sample surface and actually spoils the resolution. 20 or 30 kV is used for EDX or some "exotic" applications, e.g. to localize some contrast structures under a covering layer. It has no advantages in routine imaging.

Please read this discussion:

Good luck!

@Rehan Abid Thank you sir for your well explained suggestion.

Mohamed G. M. Kordy

You say nothing about your metallic nanoparticles, what they are, the route of preparation, or even a simple picture to show that your system is transparent (may be colored e.g. a gold sol) free from turbidity or settling (if so then the system is not nano - < 100 nm)

My translation of 'I think the DLS is not correct' is 'I do not like the (larger) DLS results'. But your question is confused. I read it that you have UV data and want to obtain DLS data from these. You can't convert UV data to DLS data.

Have you actually obtained measurements with DLS? If so you're getting much more information complementary to electron microscopy but you can't compare apples with turnips. What is being measured in both cases is totally different:

I have a bunch of questions for you:

First of all, having a light element matrix might not be detrimental to quantitative EDX (or WDX) : it all depends -as Vladimir Dusevich said- on having a "good" SEM (well calibrated for quanti), being a "good" operator (knowing what to do and more importantly, what NOT to do), and having "good" standards" (or having proved that one of the quant models works on your samples/matrix).

It is easier for example to quantify heavier elements in a light matrix that is suited for quanti, than for instance Carbon in Steel (for which EPMA would be used).

One of the ground rules would be : if your sample is not smooth, dense (non porous), homogeneous, conductive, isotropic and finally thick enough for electrons not to strike through ; then you can probably forget about precise quantitation by SEM-EDS (or WDS, does not matter).

Plus, you should be aware that "standardless" analysis, (whatever the model, ZAF, PhiRhoZ, P&P...) as provided by all manufacturers is always worse than having your personal standards, ideally on the same matrix as that you will be analyzing (most always difficult to do).

If you're not familiar with quant SEM-EDS, you might want to start with : https://www.springer.com/gp/book/9781493966745

D.E.Newbury again...

I could suggest French books as well if you read French (lots of work done in France on quant SEM-EDS models back in the 70s and 80s).

Dear Rakesh Kumar , as stated before by William Letter and Vladimir Dusevich these are different methods and have different element sensitivity.

Perhaps the differences you observed are caused by that reason, but probably it could have something to do with the way these two methods are applied to samples.

ICP AES give you information about the whole sample, since this is prepared as a solution that is sprayed into the plasma plume for analysis.

SEM EDX however, provides information from a solid sample, and that information is quite local, both in the depth direction and the analyzed area because the electron beam is focused in a tiny area of your sample and the electrons only penetrates till certain depth (depending on the electron beam energy and the sort of materials forming your sample).

Imagine that your sample is heterogeneous, for the sake of simplicity let it be formed by just 2 components (A,B) in realtion 1:1, distributed in grains of say 1 mm³ they are both soluble and can therefore a representative aliquot of your sample can be sent to the ICP-AES, which retrieves the real composition of your sample (A1B1) (remember the sampling is key). Now, you analyze another sample fraction by SEM EDX, if the beam is focused on a grain of component A, then you get the composition of this component (A), but may be some of B too, because some electrons were able to reach some grain of B, so you can get something like A0.8 B0.2, that clearly is different from the real one A1B1.

You could also hit a grain of B with reverse results. Even if you take enough EDX data from different regions on the surface of your sample, they could not be representative, imagine A and B are forming layers, they still are in 1:1 proportion, but an EDX analysis of the surface would give you mainly the information about the external layer, or just it if the layer thickness is enough to avoid the electron beam reach the second layer.

Hope this helps. Good luck with your work.

I do not understand what type of remineralization you expect to find, but crystal structure of healthy enamel is pretty dense and do not allow any significant infiltration of a resin. Of course, dental bore makes rather rough surface of an enamel, and applied resin will fill all the crevices, so there will be no flat, even interface. Additional difficulty is that resolution of standard EDS procedure for an enamel is about 2 microns (some paper erroneously state that infiltration is the same 2 micron, their authors just do not know what "resolution" means). In your case mapping is rather useless, even if pretty. I would advise to use line scan, as was already suggested by Ahmed Samir Bakry .

the attached file is useful to understand this subject.

Dear Maria Apriliani Gani,

These may be addition of impurities, high temperature and environmental conditions can reduce the formation of carbonates.

Bone mineral is not pure hydroxyapatite. The small, plate-shaped (20–50 nm long, 15 nm wide, and 2–5 nm thick) apatite crystals contain impurities, most notably carbonate in place of the phosphate groups. The concentration of carbonate (4–6%) makes bone mineral similar to a carbonate apatite known as dahllite. Other substitutions are potassium, magnesium, strontium, and sodium in place of the calcium ions, and chloride and fluoride in place of the hydroxyl groups.These impurities can reduce the crystallinity of the apatite , and, in doing so, may alter certain properties such as solubility. The solubility of bone mineral is critical for mineral homeostasis and bone adaptation.

Carbonate substitution in apatite each control the crystal’s perfection and crystallite domain size, affecting material properties, in different environmental conditions. High temperature substitution methods indicating a higher energy barrier for the formation of carbonate.

Ashish

Dear Denis Rodrigues ,

I fully agree with Dr. Gerhard Martens  , and add one comment.

In case some semi-crystalline phase is intimated mixed with the amorphous, a razing angle experiment may give some additional evidence. It will probe a higher amount of sample per unit of sample holder area. 

When such a mixture exists, the experiment gives some information. The background mainly caused by scattering at this condition would be lowered.

Perhaps it makes you sure of the points already pointed out.

Best regards

WNM

In general, proton and ion beams will also lead to secondary electron emission from a surface and therefore allow secondary electron imaging. The interaction of ions differs from electrons, for example, in the energy transferred to an electron in the sample. Due to the large mass ratio between ion and electron, the energy transferred to an electron is in general small. This means that only electrons scattered very close to the surface will be able to leave the sample and contribute to the SE image. Using ions as primary beam therefore allows to produce very sharp SE images provided the beam focus is sufficiently small. This is achieved in the helium ion microscope (HIM) where a field emission ion source is used and beam spot sizes below 1 nm are possible. The helium ion beam is also comparably gentle to biological samples compared to electrons. Furthermore, charging of insulating samples that significantly reduces image resolution can be avoided more easily in a HIM by providing electrons for charge compensation.

Other ions can be used for SE imaging too, for example in a typical Ga focused ion beam system. Here, however, SE imaging is not the primary purpose of the machine, but ion milling. SE imaging is used to find the right place on your sample before the milling is started. So, it is possible, but probably not the ideal choice if you are only interested in the SE image.

The probe depth of XPS is about 10-nm which is a surface sensitive technique whereas EDX can vary from 1 to 3 microns - "bulk" analysis technique. The thickness and homogeneity of elemental distribution in the sample will thus cause different results by the two techniques.

Faeze Hosseini

In the process of particle synthesis, the thermodynamic system tends to minimize the change in the Gibs energy. This energy consists of contributions from the structure (interactions between atoms) and the contribution of surface energy. Of all geometric shapes with equal volume, the sphere has the smallest surface energy. This natural phenomenon is clearly seen on the example of obtaining emulsions. The emulsion always produces balls, not cylinders. Therefore, our Earth is spherical.

Digital Surf is selling a version of Mountains (metrological topography software) that has a "SEM" version for 3D stereo reconstruction but also does colourization. Pretty nice results...but, it's not free.

If you're limited to free software, try GIMP and work as a digital graphics guy would : detour, select and use layers to colourize.

Or, if your sample allows it, you can use two or more detectors to generate different contrasts : use one detector image as the Red layer, another as the Green layer, etc and generate a colour image from your contrast texture (still using the GIMP).

Lots of video tutorials online.

Proper quantification of light elements (such as N) by EDS is a tough task. It requires use of standards and good understanding of the technique. I believe that your results (as well as results from the paper you mentioned) were obtained by means of standarless analysis, which produces huge errors in light elements analysis. If you need bulk analysis of light elements (not a microanalysis, where EDS excels), use other methods, discard EDS results.

Jürgen Weippert Thanks for your answer. The machine is a FEI Inspect S50, the software is included with it. I did not use it myself, I only processed the results. The ratio calculations were done with Excel, simply by dividing both Atomic percentages for each case.

After a thorough search, I found an article where it finally specified that the ratios were, indeed, calculated with normalised %atomic results. In my case, as I later discovered, many of these calculations made no sense since I had a mixture of different components close enough for the spot size to be unable to focus on a single one, and therefore was getting unusually high amounts of some elements.

When it comes to the choice of materials for MOGS (Metal Oxide Gas sensors) applications, materials which exhibit high resistance variation upon exposure to the test gas is considered as most suited. Not all metal oxides can be used as a sensor material. In the last 50 years of sensors research, the choice sensing material has always been empirical. However, the thumb rule for a metal oxide to be used for MGOS application is that, the surface chemistry of the metal oxide should be in such a way that it is sensitive to oxidizing or reducing atmospheres. The details are available in plenty of review articles like this one : doi: 10.3390/s91008158 .

Of course, the acquisition time is affecting the results:

1. Obviously, there is just a statistical effect: number of counts. The columns in the histogram are "jumping", then become stable. Just the law of large numbers.

2. Beam damages. The beam destroys the sample. This is especially important for thin samples (films, coatings, etc).

3. Carbon deposition under the beam. Even the purest chamber has some carbon contamination (SEM users know this annoying effect very well - dark spots).

4. Charging. Including local degradation of conductive coating.

Thus, in ideal world it would be easy: more counts, higher precision. But the real physical world is more complex. Experienced operators can choose the most optimal parameters of analysis. Sometimes, it is a kind of art.

Good luck!

I assume under "replica" you mean "specimen".

For publishing in bottom-feeding journal you need almost nothing, and one specimens will be more than enough.

For more presentable journal you need more specimens. At least 3 controls and 3 of interest. If you are going for statistics, then after measuring 10 specimens ask a statistician how many specimens (in addition to 10) do you need.

Dear Jun Kawai , energies above 15 kV are rather good for EDX, energies below 0.5 are not too bad, L and M lines are used widely, contamination is a serious problem, and water is specimen is unwanted substance.

Dear Prof.Ian which parameter we use in the EDS report for calculation of the composition the wt% or at% and how reliable is this method to know the composition

Hello Savy Panamkuttiyiel Minal,

The raised topic is interesting. In order to have better visibility, it is necessary to apply a coating with metal nano particles. Most often, the metal coating is made of gold due to its good conductivity and does not react with the biomaterials. Problem remains the size of particles that can change surface roughness because they are not the same size. may even block some openings. That's why the share of metal particles could be best. for analysis. This joints in special conditions with pre-fitted vacuum installations.

Wishing for success in scientific work.

Regards Emil Yankov

100 to 200 nA? Are you sure? It is huge even for a FIB (typically max ion current is about 100 nA). The spot size will be terrible (micrometer?!). Most common parameters for EDX - current from 0.1 to 1 nA, HT from 10 to 30 kV, almost all normal SEMs meet these conditions.

This is not the way to get PDF positions. Try to search different countries in your research area. Send an emails to the concern professors by updated CV and your publications list. Wish you good luck.

Of course you should not crash your specimen. The worst thing to do, actually. Your beads are small enough for SEM, so you can study their surface and you can crack in half some of them to observe inner structure.

TEM specimen preparation is much more challenging, your lab should have proper equipment for materials specimen preparation.

Anyway, you will not get answer on your question about " location of the cations added in the crystal lattice and adsorbed gases in the pores" with the help on conventional electron microscopy.

Go for XRD

I agree with Walther, but I guess XPS would be more appropriate to give accurate answer. EDX is very tricky and you need to know many things, basically the EDX detector gives you numbers and then you need to think and do quantitative analysis to figure out exact contents of the element. In this regard oxygen is one of the trickiest element to play with and its not easy, even with XPS.

You have very good EM facilities at your university and I believe you can discuss your results with an operator face to face, in detail. For sure results you were given are not good, not up to the level I would expect for your EM lab. For beginning I would ask these questions:

- Why C content was so high? Was specimen coated with C (but who need it for a metallic specimen?) or SEM is just very dirty, with high level of carbon contamination?

- Where O and F came from? Wrong identification?

- Why quantification was performed without utilization of standards (standardless quantification is prone to errors)?

- In how many spots analysis was performed (test for homogeneity and/or presence of a second phase)?

For beginning you can discard results for C and O and normalize the rest of elements. It will give you some insight, but results will be still poor. For example you have too high concentration of S, possibly because its peak was superimposed with Nb L peaks.

1. Get synthetic HA , check your system with it.

2. You cannot expect to get Ca/P ratio of 1.67 with any EDS system if you do not use proper standards. You have to perform quantitative analysis with standards.

Dear colleague, It is difficult to speak about a better technique is such a case. It really depends on the question you would like to answer and on the materials you are planning to use. The particle size is playing a role. TEM or SEM? In any case the smaller fractions, let say below 5 nm diameter, can only be analyzed in a satisfactory manner in a “very good” SEM free of astigmatism and please using some gamma-control object for adjusting the brightness and contrast. Only changing the brightness the diameter of nanoparticles can be varied easily between 80% to 120 % of nominal diameter. This effect is stronger for small particles than for bigger ones and influences further calculations containing the volume, density... some interesting calculations before starting experiments will be helpful, e.g. if the nanoparticles are very small, most metals will be present as oxides if working in air. Bigger particles will be covered by oxide layers, some of them contain sulfur, chlorine , etc. An idea of the dimensions for non-corroded particles you may have, if you calculate the number of atoms contained in a 1nm diameter gold nanoparticle. Good luck. Alex

How do you calculate 1 wt%?

EDX measure what you have on the surface + ~20 micron down in the volume, because you have light carbon matrix. Then you use quantification tool (depends on the model of your EDX spectrometer), this tool calculates weight % of what microscope and EDX detector are seeing. This literally mean that mostly you will have carbon, because it's your matrix and everything is contaminated with C-based compounds. Thus, your 1wt% is automatically incorrect.

The best ever option is dissolve Co3O4 from a weight portion of composite and simply titrate it. 2h of work and you will have 100% quantitative result!

there is a transfer module which can make it possible. Example below:

Dear Gerhard

Say my initial weight of filter paper is 142.046 mg and final weight of filter paper is 142.302 mg.

I get EDX results in weight composition of elements.

E 1 = 10%

E 2 = 35%

E 3 = 67%

Then as per your suggestions,

Weight of individual element,

E 1 = (10% / 142.302)

E 2 = (35% / 142.302)

Grace:

Kindly see this link for useful insights.

Best

Syed

Probably you already checked the Oxford Instruments webpage for data export options (https://www.oxford-instruments.com/products/microanalysis/energy-dispersive-x-ray-systems-eds-edx/eds-for-tem/aztectem/data-processing-and-export), but since we don't know which software from OxfIns are you using (Aztec, Inca, ...), it will be hard to suggest some useful protocols...

Anyway, this script from HyperSpy can import Oxford data (.rpl): http://hyperspy.org/hyperspy-doc/current/user_guide/eds.html

and it comes with a rather nice manual.

Also, here are some useful hints how to access the .raw data in Aztec:

For SEM analysis: Lyman, Charles E., et al. Scanning electron microscopy, X-ray microanalysis, and analytical electron microscopy: a laboratory workbook. Springer Science & Business Media, 2012.

For XRD analysis: Waseda, Yoshio, Eiichiro Matsubara, and Kozo Shinoda. X-ray diffraction crystallography: introduction, examples and solved problems. Springer Science & Business Media, 2011.

For EDX analysis: Russ, John C. Fundamentals of Energy Dispersive X-Ray Analysis: Butterworths Monographs in Materials. Butterworth-Heinemann, 2013.

The picture looks like low-mag SE or SE + BSE (some microscopes can use both detectors simultaneously) image. It is fundamentally impossible to convert it to an elements map. As Dr. Dusevich said, use EDS.

Good luck!

First of all, is the AC commercial one or you have prepared it? how have you mounted the sample, on glass substrate or anything else? AC should have in principle, carbon and surface oxygen from the process...Silica or Si also would be an element from background, either environment or support material...but elements like K or Ca probably from the support material...unless until you treat the AC with some chemicals, what did you expect from EDX?

Both methods for good quantification require solid knowledge of techniques and are prone to errors. In addition quantification with EDX is very difficult when specimen has large amount of light elements in its composition (like graphene oxide); in this case I would rather believe ICP-MS results. But value of Pt/Ni ratio should be more reliable than wt%, so you may be interested in comparison of this ratio between methods.

There are several preparation ways which can be called "fixing in hard matrix". The easiest and undemanding (to my opinion) is to make polished section in epoxy resin.

First of all you need an epoxy resin and hardener. Usual epoxy from hardware store is applicable (with certain limitations). Howewer using epoxy designed for scientific needs (e.g. Struers EpoFix or analogue) is easier and gives better result. If you have some contacts with people performing sample prep for geological samples you may ask them about epoxy (or even to ask them to prepare your sample).

P.S. If you did not work with this epoxy before you should previously try to make an empty sample to check how does it harden.

Then, you have to cut your sample. The flatter will be cut - the easier will be following work. After cutting you can grind the bone on a coarse sandpaper a little to flatten the surface. Avoid using dirty tools or you will get unexpected results!

Then wash and dry the sample. Put a piece of double-sided sticky tape on a flat surface (usually glass is used) and place flat side of your sample on it. Place a plastic ring around your sample (I use rings cut from silion hose) and prepare epoxy with hardener. The component ratio is usually written on a bottle. Mix it properly! Then pour it into the ring (for porous samples you can put a few drops of mixed epoxy directly to the surface of your sample to fill the pores and only then put it on a tape). Epoxy loses viscosity with temperature so you can warm it up to 50C for better result. It will harden in a day, but for further preparation it will be ready after 3-4 days.

P.S. If you grease inner surface of the ring with a small amount of silicon lubricant you can remove the ring easily.

After 3 days unstick the sample from base and ring (it can be hard, be careful!), wash it from silicon lubricant and sticky tape's glue. Then grind it on sandpapers (e.g. from 240 to 1200) and polish until you get good surface (e.g. on diamond 6, 3, 1 microns).

Here it is written how to make polished sections:

https://davehirsch.com/other/thinsections/

Probably its because of the presence of C-O species and/or other contamination. You should analyse the O1s and C1s XPS peaks and use for quantification only the component of the oxygen peak that is related to titania.