Please explain the procedure of sample preparation, etching method, etchants required etc. for green specimens of FUSED SILICA to take SEM microstructures. Without etching I have done sputter coating and when the microstructure image is taken some black shades are appeared on the image due to the charge in the particles. How to get rid of this.
Please explain more خد what you are looking at with SEM or what depth are you willing to image? are you collecting secondary electrons or back scattered electrons?
If you have charging even with coating I would suggest lowering your accelerating voltage or lowering your filament temperature to decrease the current. also try decreasing your spot size.
Good luck
Dear Sir Amirhessam Samadaghaei, Thank you for your kind response. I want to go for 5micrometre depth and wish to collect secondary electrons. I have tried lowering the accelerating voltage but the images are not clear. Does the sample to be etched with any chemical.
Dear Kishore,
to reduce the sample charging you can lower the voltage to the critical energy of Fused Silica - for example critical energy for quartz is 3kV. -> You have to play with it a little bit to find the voltage at which your sample is not charging. Or look for the papers where they observe it in SEM and try to do at their conditions.
Or you can coat the sample with carbon on metal.
Dear Rostislav Váňa, as per the journals many of the authors are using a voltage range of 15kV and they are getting good images.
I don't think you need etching. Have you coated your sample? Is your sample getting charged (imaged areas appear brighter)? Have you tried low spotsize?
If your sample is not charging try increasing the accelerating voltage, sometimes tilting the sample a little bit helps as well. based on my experience Silica is very hard to image.
Dear Amirhessam,
I have given gold coating to the sample. The sample is getting charged when the voltage is 8-20 kV and the magnification ranges from 2-10 micrometer. The image obtained has black shades.
What are you trying to find out about the sample? If you say green- do you mean not fired, pressed sample or is it powder?
Dear Biljana, Green sample means not sintered and it is a casted sample.
Dear Kishor
Try to give gold coating once more and do the sem characterization at
I need to do optical micro-structure of aluminium silicate and fused silica which is used in investment casting mould .
Kindly suggest what should be the etchent used ? any research material supporting the solution?
Thanks and regards
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