Recently we are working on silicate glasses, like soda-lime glass. My question is: What kind of structure should it give using transmission electron microscopy ? Should it give an amorphous structure, or a polycrystalline structure ?
Since I am not so familiar with TEM images
Thanks in advance
actually i am working on laser induced bulk damage ,and want to study the compressed region due to micro explosion in the soda lime glass,after obtaining the transmission electron microscopy images ,this compressed region shows polycrystalline and some nano crystal structure.i wonder ,because soda lime has amorphous structure
Interesting. I never heard that laser can change a material from amorphous to crystalline structure. Please check your sample again, whether it is soda-lime glass or quartz. If it is soda-lime, I think you get a good result to publish.
Yes, good results if you have soda-lime. I was working with soda-lime glasses doped with metal particles by Laser Ablation Backwriting. I characterised them by TEM (you can see my work with TEM studies: F. Rey-García, C. Gómez-Reino, M. T. Flores-Arias, R. Lahoz, G.F. De La Fuente, W. Assenmacher and W. Mader, "Microstructure of planar glass substrates modified by Laser Ablation Backwriting (LAB) of metal targets", Appl. Surf. Sci. 307 (2014) 645-653 ) and in effect, you see and amorphous material. In hard words, You can see an more than less uniform region of the same colour. If you have cystalline structures, you should see 'defects', 'defined structures', ... some way of 'pattern' Moreover, your TEM have and XRD unit?? If you have diffraction peaks you have crystallinity??. However, it is possible you have nanocrystals without significant XRD signal (see my work: F. Rey-García, M. T. Flores-Arias, C. Gómez-Reino, G.F. De La Fuente, S. Berneschi, S. Pelli, G. Nunzi-Conti and G.C. Righini, “Structural and optical characterization of ZrO2:CeO2 slab waveguides obtained via Sol-Gel”, Opt. Mater. 35 (2012) 97-101). I hope be useful for you.
By definition, if it's glass, it has an amorphous structure. You can determine which amorphous structure using fluctuation analysis, but that's an advanced technique that you can worry about later. For now, all you have to do is go into diffraction mode. If you see Bragg spots, then at least part of your material is crystalline.
Laser-induced crystallization of amorphous material happens all the time. See my publication list for a few examples.
If you want to know which area is producing each Bragg spot, you can insert an objective aperture and, in diffraction mode, move the aperture to let one of the Bragg spots through, then go back to imaging mode and see which area lights up. Another thing to do is to look at the sample in imaging mode and physically tilt the sample back and forth (either by hand or by using the motorized tilt-wobbler function, depending on the model of microscope you're using). If you see discrete areas light up and go dark as you tilt, then those are single crystals. The amorphous areas will hardly change in appearance at all as you do this. You should actually do this tilt-wobble procedure for every sample you look at. It's amazing how much you can learn about your sample in less than a minute just by doing this, once you get used to interpreting what you're seeing.
The methods I'm describing are quick-and-dirty tricks to qualitatively figure out what you're looking at. If you want to be quantitative about it, I strongly recommend a thorough read of the textbook by Williams and Carter. It's an excellent practical guide.
Bryan W. Reed tnx for your comments,i will first study your publication ,then if i have some question ,i will try to catch you.
You may do electron diffraction to check wheather there are tiny particles in the glass matrix. You can do chemical analysis of local area down to nano- or even atomic level by STEM, EELS, STEM-EELS. STEM is sensitive to local atomic numbers of atoms.
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