Dear all
I got some suggestions about one manuscript from referee. one question is so hard to response for me.
the questions as follows:
the authors need to ascertain that there are negligibly small compositional fluctuations in the compositions studied. Hence, a line broadening analysis of their ceramics are needed. Compositional fluctuations cause line broadening d-spacing variations (also wrongly known as microstrain). Hence, the authors need to ascertain that no such broadening is present to an appreciable extents.
We study BaTiO3-based ceramics via doping Sn. the ceramics with different content Sn can affect the dielectric properties, for example, Tc becomes lower and lower with increasing Sn. high Sn content lead to diffussiness even relaxor.
Here, I donot know how to verify the compositional fluctuations in ceramics.
EDS, or temperature-dependent permittivity at different frequency, or other techniques?
what is that mean of "line broadening analysis ?
Thanks in advances
First thing to do is analysisof the FWHM of diffraction peaks, for example for (111) peaks in the case of BaTiO3, as a function of composition. In a first approximation, tThe FWHM is correlated to the size of the coherent diffracting domains, themselves correlated to the compositional fluctuations.
The problem is much more complex: line broadening in XRD may be caused by other factors, e.g., crystallite size and strain being the two classical causes of line broadening. These two components of broadening can be separated by a Williamson-Hall type analysis or by the use of modern Rietveld refinement software. In order to relate line broadening to compositional fluctuations, you would have to assume that contributions from size and strain are negligible or constant. Another approach would be to do EDX or preferably WDX chemical analysis in the SEM, EPMA, or even TEM for the best spatial resolution. Analysis for Sn in BaTiO3 should be relatively straightforward depending on the doping levels that were used.
Dr. Gregory R.Lumpin and Dr.P.Marchet.
Thanks a lot for your suggestions and comments.
Indeed，it is so difficult to verify slight compositional fluctuations
in our ceramics. Your methods are sutitable and straightforward for
obvious compositional fluctuations.
I check lots of papers about compositional fluctuations.
I found that one paper shown that broad dielectric maximum is attributed to compositional fluctuations.
( see Coondoo et al,JAP, 113,214107 (2013)) In additions, dielectric maximum and dielectric loss change slightly with increasing frequency, which
also indicates the presence of local compositional fluctuations. see Du et al, Ceramics International,29, 9299,(2013).
Based on aboved viewpoints, I measure temperature-dependent dielectric constant at different frequency.
Similar observations is obtained in our samples. Such compositional fluctuations become more obivious with increasing Sn content.
But we all think that is so slight and can not affect us study their intrinsic properties. The cations radii differencs Sn4+ (0.69 Å) and Ti4+ (0.605 Å) may induce random distribution of Sn and Ti cations at high Sn content,
which induces slight compositional fluctuations. It is so hard to verify directly slight compositional fluctuations.
Here, we only choose this to explain it.
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