In powder diffraction, the Rwp does not have reference values, it depends on your data. Is the difference curve sufficiently flat? Could you please upload the Rietveld refinement plot so we can take a look to it? What about GoF parameter?

In 2317 bmp document, it shows the refined results. In 2348, the corresponding plane are marked with different color: blue represents cassiterite phase, dark green represents malayaite phase. The refined parameters are as follows: sig= 3.4526649; Rwp (%) = 21.785355; Rwpnb (%, no bkg) = 25.074345; Rwpnb1 (%, no bkg rescaled) = 21.632772; Rwpnb2 (%, no bkg rescaled^2) = 21.62194; Rb (%) = 13.703821; Rexp (%) = 6.309722. Thanks a lot！@Marcella Bini

I cannot see evident problems on the two employed phases. The main problem is that there are numerous small unidentified peaks, that can contribute to increase the sig value. Try to identify them and insert their crystal structure during the refinement

Dear Kun Li.

As Marcella Bini commented, the pattern has many small impurity peaks (more than 10). Therefore, the Rietveld refinements with the 2 phases resulted in high discrepancy factors. In addition, when checking the CIF file that was sent, they have negative Biso parameters, which is a bad indication. On the other hand, it is not correct to refine the texture parameters at this stage, it should be left until a better refinement is achieved, almost at the end. I did the same pattern adjustment with the 2 phases using Topas and the Rwp is still high, but I got similar Rwp without using the texture parameters. To solve this problem you have to go back to the powder diffraction database (Qualx2 and PDF-5+) and assign all the extra maxima. If the elemental analysis was performed, it can complement the search-superposition and be performed in a simpler way. With these new phases added, the Rietveld refinement should come down to the right values.

Best regards

Analio Dugarte