I carried out Xray diffraction for microcrystalline cellulose (MCC) and below is

the attached file , it shows two main diffraction peaks of the 2 ceta angles at 11 and 22.5 degree.

i have two question, why X ray peaks of cellulose in literature is different from my results ? ( appears at 16 not 11 degree ). secondly, for calculating crystallinity index (CI) ; there are more than one method to calculate ( CI )

i have calculated it from the area under peak using origin software is that OK ? or calculating from Peak height is better?