There exists graphical methods of indexing tetragonal (including body centered tetragonal, bct). You can use Hull-Davey chart or a Bunn chart. The methods have been illustrated in the book "Elements of X-ray diffraction" by B.D. Cullity in section 10-4, p. 330. In similar graphical method you can also index hexagonal and rhombohedral systems. Indexing these system is fairly straightforward because of the small number of unknown parameters. For orthorhombic, monoclinic and triclinic systems because of the larger number of unknown parametrs that are involved, the indexing becomes very difficult. But you can use FULLPROF to index the pattern as well. But for this you must know the approximate lattice parameters and then ask the program to refine the parameters to fit the positions of the diffraction peaks. By this program you can index any structure provided that you have good starting lattice parameters.

There exists graphical methods of indexing tetragonal (including body centered tetragonal, bct). You can use Hull-Davey chart or a Bunn chart. The methods have been illustrated in the book "Elements of X-ray diffraction" by B.D. Cullity in section 10-4, p. 330. In similar graphical method you can also index hexagonal and rhombohedral systems. Indexing these system is fairly straightforward because of the small number of unknown parameters. For orthorhombic, monoclinic and triclinic systems because of the larger number of unknown parametrs that are involved, the indexing becomes very difficult. But you can use FULLPROF to index the pattern as well. But for this you must know the approximate lattice parameters and then ask the program to refine the parameters to fit the positions of the diffraction peaks. By this program you can index any structure provided that you have good starting lattice parameters.

Dear Volker Klemm,

I am really appreciate your help for this question as well as my previous questions. Thank you for your time.

@Tapan Chatterji- Thank for your answer also.

I agree with you that the Tapan's answer is very good, but in addition you can also find information on analysis of the powder method for lower symmetries such as hexagonal, tetragonal and orthorhombic in Chapter 5 of "X-ray diffraction" by B. E. Warren