Hi guys, I am using Xpert Highscore Plus to carry out a Rietveld refinement for my XRD pattern. I am looking at the lattice parameters and weight fractions. I am fine with the phase identification. However, it tends to show that my secondary phase (MgO) has higher weight fraction than the primary (MgB2) after Rietveld refinement. I suspect the main peaks of these 2 phases are too close to each other which the program cannot differentiate properly as the primary phase should be in much higher weight fractions. How should I refine it then? Please advise. Thanks guys.