Question

Xrd data difference between chromium and copper radiation

Answer 1

what is Xrd data.
I don't know but thanks for ur points

Answer 2

have two diffractometers, one with Cu and one with Co anode. The Cu is the most widely used, but samples that are rich in Fe, Cr, Mn will fluoresce under the incident Cu Ka beam and create polychromatic radiation. Exactly what you don't want. It can lead to strange shaped and elevated backgrounds. The answer is to choose an element for the tube that is appropriate to your sample or experimental requirement; in this case Co for samples wth Fe. The resulting 2-theta values will be different for the same material on the two anodes, but the d-spacings will always be the same. So if you are reporting d-spacing then it does not matter which anode you use.

You also ask about why not Kb, well it has much lower intensity and would give very poor signal to noise if it were used as a main line (I'm not sure how you would eliminate Ka!!). Almost all diffractometers will have a method of monochromation to remove the Kb component, either a Ni filter on a Cu anode or Fe filter on Co anode, or a graphite secondary monochromator, or a primary monochromator or mirror.