Did you tried X'pert data analyzer software? Its easy to use.

Ok. So what's the problem then? What part of answering your question don't you get?

a) using the internet to search for articles and software appropriate to your needs

b) not understanding how to actually figure this out yourself without software if you already know the three phases in your pattern (wow I hope not)

c) not being able to identify the phases in your sample (in which case, you need to complement with other measurements (EDS in SEM for example) to narrow it down.

d) or you think that because of the internet you don't actually have to read or learn anything for yourself. You can just ask extremely broad and vague questions expecting someone to explain to you exactly what you need to solve the problem, which you didn't even take the time to specify in enough detail for anyone to answer, without having to actually do any literature searching on your own?

Oh, and X'pert software is easy to use because

a) it's expensive as hell

b) it doesn't allow you to think for yourself

If you don't understand and haven't solved a certain type of analysis problem on your own without software sold or written by others, then please please don't use some "black box" software to analyze your data (Unless you don't care if you have the correct solution).

Dear Lawrence, thank you for your answer. I think you are right, I should have looked it up more carefully before asking it here. I knew that so many people use Rietveld method to solve it, but I was wondering if there are other possible ways which obviously I could looked it up in internet before asking it. I really appreciate your time and I knew for sure this is not a place to ask any questions pops up in my mind. By the way, since this is your area of expertise do you have any good books for me to start?Thanks.

I suggest you to use PCPDF WIN to do search match for qualitative analysis. After doing this now you are sure what's phase present in your data. For example nitrid A, B, and C (JCPDS file No........). Download Rietica software from Brent Hunter, Australia and install it  in your computer. It is free and very easy to install. Download PDF data of your samples (A, B, C) . I think your institution has this software. Otherwise ask for help of your friend to copy just for those files (A, B, C). Now do quantitative analysis by Rietveld method. You can study how to operate the software by following the examples included in the software. If you have a problem to conduct the refinement process, you can contact me anytime. Regards

I suggest you also GRAMS , you can insert spectra from different machines.

I highly recomend you X'pert data analyzer software... it is enough... 

I highly recommend not using X'pert software. Not only is it insanely expensive, but it also teaches you to not think. There are many many free software programs which can do exactly what you need and also allow you to understand whether the answer you got from the program makes sense, since it is not a black box which has had very little testing to find bugs or anyone who does not work for the company selling it writing code to improve it on a daily basis. The real question is do you want to be a scientist or a technician? If you decide you don't want to be a scientist but would rather think less and just follow technical instructions given to you by a company or your employer then hell yea use X'pert. Otherwise don't even go near it unless you already know how to do what it does using freeware and your own brain.

I agree completely with you Lawrence. Any software is not useful if we don't know the basis of xrd. The solution of the problem may be very simple if the mass absorption coeficients of the three nitrides are similar and not very much peak superposition is expected, but could be something more difficult if great differences in absorption is present. I can recommend the book of Zavyalova and my own papers in these fields.