It depends solely on the interplanar distances (d) inside the crystal structure. 2dsinθ = nλ. For low angles you ll find diffractions corresponding to large interplanar distances. It is also limited by used wavelength. Using CuKalpha radiation (0,.15406 nm) for 2 theta angle 5° you ll get interplanar distance d = 1.76 nm (d = λ/(2sinθ) = 0.15406/(2*0.0436)), e.g. in zeolites. Conversely in high

theta range you ll find many reflections especially for low symmetry structures and you ll only get low intensity lines because structural factor is decreasing.

So basically - it depends on the character of the compound you are measuring and information you need. For sure you can perform - 5-110° 2theta measurement if it helps you.

It depends solely on the interplanar distances (d) inside the crystal structure. 2dsinθ = nλ. For low angles you ll find diffractions corresponding to large interplanar distances. It is also limited by used wavelength. Using CuKalpha radiation (0,.15406 nm) for 2 theta angle 5° you ll get interplanar distance d = 1.76 nm (d = λ/(2sinθ) = 0.15406/(2*0.0436)), e.g. in zeolites. Conversely in high

theta range you ll find many reflections especially for low symmetry structures and you ll only get low intensity lines because structural factor is decreasing.

So basically - it depends on the character of the compound you are measuring and information you need. For sure you can perform - 5-110° 2theta measurement if it helps you.

Dear Khaled Saif Aldin,

when performing XRD, the peaks with the highest intensity are typically the low Miller indices ones, e.g. (100), (111) etc.. These are typically associated with lattice constants that translate into 2 theta angles that are between 20° and 80°. Of course there are also crystals that show their peaks at lower or higher 2 theta angles.

Best regards,

Hi, Aldin,

It is very good question. Actually the range of 2theta depends on various parameters such as wavelength of the X-ray radiation or neutron/electron beam, crystal structure of the materials, and purpose of the study etc. When all the highly intense intensity fall in the short 2theta range, then we choose short range otherwise long. Most of the systems exhibit most intense peaks in the 20-800. For Rietveld refinement people use long range scan.

Most common phases and elemental compounds have the XRD peaks between the range of 20-80 degree even 20-60 degree 2thetas if Cu is the anode. If the Mo is anode, the phases appear between the lower range of 5-40 degree 2thetas due to higher energy of Mo that produces smaller wavelength. n times lambda is equal to 2 times interplanar distance times sin theta. As lambda decreases, sin theta decreases simultaneously for the same d.

Dear Michal Hegedus, Mark-Daniel Gerngross, Dinesh Kumar and  Ali Özer

I am so grateful for your suggestions.

highest intensity are typically the low Miller indices ones, e.g. (100), (111) etc.. These are typically associated with lattice constants that translate into 2 theta angles that are between 20° and 80