Hello,

as I understand your sample is a mineral (kind of rock). Sample should be powdered and an average diameter of the grain should be no more then 5 micrometers.

Your results are typical for the textured samples (samples with preferred directions). Such result you can observe for bulk samples or powdered samples prepared incorrectly (to large grains, sample prepared in a way which creates preferred directions).

For the analysis it is good to know the elemental composition of the sample (if it is possible to use the composition in your program).

Jaromir

Any hints about the chemistry and geological identification of your sample ? Otherwise it will be very difficult to identify your phases with only three clearly defined peaks. In any case the very high diffuse hump suggests a high amorphous content. Maybe much higher counting times can help to identify more peaks from the background noise.

Regards

Yes. The sample grain sizes were around 180 um. Location is Mangalore, India. The nature of the soil is laterite. This rock is seen with red to pink red and more white patches are seen along with that. The EDS says it consists of Aluminium, Iron, Oxygen, Silicon  etc.

Is this the same data set Pragadeesh?

What is the target (anode) or wavelength for the incident beam for your XRD? What beam conditioners were used? Have the "Metadata" for the XRD scan printed for this data set.

Q. What is the hump?

A. "The hump is seen possibly due to decrease in intensity as 2theta increases. The one who operated suggested this explanation."

No no no............... :-)

Still need:

This is Cu anode. That hump shows an amorphous phase probably Si, Al, O compound, what is the color of ur specimen?

Due to the particle inhomogeneous the intensity was buried.

Here is the best candidate from ICDS base on ur elemental analysis. Fe compound can't be see due to fluorescence.

See the advantage of posting the actual data :-)

Good work Maykel!

Suggestions:

The nature of the sample preparation:

1. Ball milling to powder rock samples.

2. Random sample taken (no particular sized grains used but less than 400 um)

3. A glass sample holder is taken and a gel (they say 'vacuum gel') is spread across 2*2 cm.

4. Over this, the powder is applied to get uniform thickness of about 2-3 mm from glass surface so as to avoid radiation hitting glass.

Nature of radiation:

1. Target material : Copper

2. Radiation : K-alpha

3. Wavelength: 1.542 A

4. Voltage: 20 KV

5. Current: 30 mA

Nature of sample:

Color: Red with white patches with more white constitutes.

I am posting the image of sample used in next thread.

Here are the images of the sample analysed.

Pragadeesh, are these natural rock chips?  You said in your preparation method that you made a layer 2-3mm thick on the sample plate.  Is the upper surface of the powder at the correct position?  If it is too high or too low, the peaks will be shifted significantly.  I wouldn't worry about the glass sample holder contribution.  If your mount takes a simple glass microscope slide, then you should have a very thin coat of vacuum grease sprinkled with the sample powder.  All the loose powder should then be knocked off so you have a very thin layer of sample (a few micrometers thick, not millimeters).  In the meantime, I'll see what I can make of your pattern.

Jim

Those hump may came from the glass substrate, u also loose the intensity.

Try to compact ur sample instead of using glass substrate.

A grain size of 52900 particles would be needed! See: Klug, H.P. & Alexander, L.E. X-Ray Diffraction Procedures. John Wiley, New York, 1954

Increase ur voltage to 35

The last image was just powdered sample. I have not given the image of sample on holder. The upper surface of sample is flattened on sample holder.

Dr.James, I could not get what will be effect if we place a thick (2-3mm) sample. I have a correction in what I have mentioned. I said it was 2-3 mm thick but actually it was about 1 mm to 1.5 mm max.

The suggestions like changing the target metal for x-ray radiation (i.e. Iron target) and changing the voltage to 35 KV are good for the more accurate analysis. I agree with you.

But here, we are not allowed to change these parameters. The infrastructure in institutes like ours, won't support varied exploration in the facilities available, as the numbers of such facilities in a single institute is 1 or 2 or sometimes nil.

No Sir. First time I am hearing from you as I'm not good at mining and mineralogy. Can you suggest some standard reference for this analysis.

Intuitively, I would think that the conditions of solidification of the "rock" could be conducive to the vitreous phase formation if the solidification was rapid. So the "hump" deserves some additional attention after deconvoluting  the "fluorescence" effect.

Forget the advanced "polarizing microscope" that Ken has thrown at you. Do you have any micrographs of the "rock" before pulverizing? Don't you think that would be the basic step before embarking on a blind fishing expedition in XRD. I suggest you start back from "basics". Look at the sample with a microscope or even a modern high resolution digital camera (use the cell phone). There is so much information in a simple "metallograph" (micrograph with/without etching) that you are ignoring and hence "groping in the dark" :-)

With Cu radiation you cannot see the signal clearly, due to the Fe content resulting in high "background" signal. Tough proposition to deconvolute the signal of interest from all this mess, hump and all. Good Luck!

"But here, we are not allowed to change these parameters. The infrastructure in institutes like ours, won't support varied exploration in the facilities available, as the numbers of such facilities in a single institute is 1 or 2 or sometimes nil." This is a limitation universally experienced by most folks that desire to use XRD as a NDE Nano structure evaluation tool. The main reasons for such a paradigm are, in my opinion:

• Protracted alignment process using conventional detectors when changing tube.
• Inability to view real time 2D XRD signal.

Remedy: Find an institution in India that has the other (Fe) tube installed to inspect Fe bearing materials like (steel). They are all around you. Bhadravati Steel in Karnataka was home to one of the oldest special steel companies in India. still around? You think they'd be doing some XRD to study their "fluxes"? These "fluxes" and "slags" from the steel making process would have similar microstructure as "lava rocks".

https://www.researchgate.net/post/Bloody_Murder_Why_is_there_nearly_such_a_visceral_response_to_any_disruption_to_alignment_of_existing_diffractometers_by_XRD_users_technicians

Dear Dr. Ravi, I am finding your information useful that to start with micrograph. For characterisation of one sample, how can these micrographs will help. Dr. Kenneth and you may know those great things underlying in simple micrographs. But how can I extract those info from them.

Try this "In the present instance the white and the red could easily be separated and individually X-rayed."

I suspect the "red" would be the Fe rich constituent. That means the other components may provide a lower fluorescence diffractogram with Cu radiation.

If you insist on using XRD, best solution is to leave the sample "as-is" and use other wavelength X-ray incident beam (to minimize fluorescence)  as suggested earlier. You'd have had the answer by now :-) 

A micro focus XRD instrument may also be used to examine particular regions on the sample in combination with a "petrographic microscope".

Hi Mr. Sekar

You can calculate D-Spacing with XRDCALC v5.5 software then you can find your mineral name in this site:http://webmineral.com/help/XRayDiffraction.shtml#.Vc3wpX2HrTS

i am calculate your data in attached file.

Best regards,

 Thanks to everyone for helping me in gaining knowledge about the X-ray analysis as well as sample preparation and the critics on the results is very useful. Dr.Kenneth and Dr. Ravi played significant roles in this active discussion, whose participation in future discussions will be benefiting the community for sure.