1. Qualitative analysis of object image
Phase refers to a compound with a fixed structure formed by various elements in the sample (including elemental elements and solid solutions). Any crystalline substance has a specific crystalline structure (crystal type, cell size and particle type, number and distribution) and component elements. A substance has its own unique diffraction spectrum corresponding to it, and the diffraction spectrum of heterogeneous substances is irrelevant. Simple superposition of diffraction spectra of independent existing phases.
Phase qualitative analysis can be based on the X-ray diffraction pattern (peak position, intensity, element composition) of the sample to search and match with the sample diffraction database to determine the phase composition.
On the basis of phase characterization, we can also see a lot of useful information: space group, cell parameters, Bragg position and so on:
2.Semi-Quantitative Analysis
S-Q semi-quantitative folding premise:
(1) It is meaningful only after the phase of the possession is determined;
(2) Phase quantification by peak height and I/Icor value;
(3) I/Icor value from PDF card, users can also enter I/Icor value;
(4) The I/Icor value of the structure library is generally more reliable than the measured value.
3.Rietveld Quantitative Phase Analysis without standard (holocrystalline phase)
The diffraction spectrum of polycrystalline mixtures with different phases is the superposition of the weight (scale factor) of the diffraction spectrum of each component phase. Although the diffraction intensity of each component phase is affected by other phases (the total mass absorption coefficient), it is proportional to its content, so it can be obtained by the full spectrum fitting and refining.
