Good morning,
I'm trying to quantify the crystallographic structure in TBC YSZ APS aging at 1100°C for duration between 24 and 1000 hours. I'm using Highscore plus software (Panalytical software).The ZrYO2 phases present in those samples are two tetragonal structure with different amount of Y and a cubic structure. I tried to refine the structures and consequently to quantify the phases.
After the background and the scale factor refinement, I refined the crystallographic parameters and, after that, the profile parameters for each phase. In every step I insert the phases one by one, but if I change the order I obtain weight percent totally different.
Moreover I refine a sample aging for 24 hours with a sequence that produce a good agreement and a reasonable result in term of phase composition; if I use the same sequence in another sample (for example aging for 100 hours) the results is not reasonable in term of quantification.
Which is the correct strategy in quantification by rietveld refinement? Should I find a unique strategy and keep it for every sample or I should change depending on my sample?
thanks
What kind of XRD data did you use? This can have a significant impact on the possibility to distinguish the different phases.
I used XRD pattern obtained by a powder diffractometer with Cu radiation. I analysed the sample surface (not milled sample) placed on zero-background holder. I select slit and mask in order to obtain signal only from sample
no,I'expect that the quantities change with the time aging, but my problem is for each refinement. I expect that the sample aged for 24 hours and 1000h are refineble with the same procedure (as profile terms that is necessary to refine for example). If I obtain a good results in term of index agreement with two different procedures but very different quantification, how I can select a strategy?
If you don't use monochromatic radiation, you will get troubles. The peak width + the presence of the apha2 peak will not allow you to refine the different phases. The software will simply try to fit with your different phases the difference between the measured pleak shape and the modeled peak shape of the main phase (t'-YSZ). Otherwise if you use monochromatic radiation, you should be able to refine the different phases but you have to fix some parameters, some of them being too strongly correlated to allow to refine them simutaenously (even in some cases you cannot refine them at all). this happens when the amount of the cubic and low yttria content tetragonal phases are low, as expected in your samples, where you should still have at least 70% of t'-YSZ. You can also check if your refinement procedure works well, by checking the results of the 25h annealed sample where you should still have a '100%' t'-YSZ composition.
thanks a lot for your answer. unfortunately I can't use monochromatic radiation. I try to check my procedure with the sample aged for 24 hours and I'll see if I can obtain reasonable results
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