It is very common for nano-size or fine powder to agglomerate due to moisture entrapment. I usually face problems regarding powder preparation for FESEM/SEM. Until the imaging process, I usually see highly agglomerate powders until the grain or even the shape of the powder cannot be observed.
As attached is one of the powder sample that I obtained by using FESEM. I am using a normal sample preparation technique where the powder sticks on the carbon adhesive tape. Any suggestion that I can improve the sample preparation prior to imaging? Kindly note that, this micrograph is not from a sintered sample
Do not use sticky tape for nano powders. Make powder suspension (water or alcohol), place a drop on a smooth substrate (glass, plastic) and smear it a bit. Let it dry, coat and observe.
Do not use sticky tape for nano powders. Make powder suspension (water or alcohol), place a drop on a smooth substrate (glass, plastic) and smear it a bit. Let it dry, coat and observe.
To observe and determine the shape of nano powder particles I suggest to cut and polish the sample in an Ion Beam Milling machine usefull for cross-section polishing prior to SEM analysis. I am sure you will get very good results. I have got sensational results using Ion Beam Milling on arsenic sulphide nano particles. Often you get poor images using SEM just only looking at the surface of single particles or agglomerates. To discover the sharp shape and the inside of the particles is much more exciting. The Ion Beam Milling machine is very expensive, but it is unbeatable. Try it!
Hi Guenter,
Thanks for your response, FIB is great but pricey. I agree that, single layer on the surface not often represent the whole shape/particle distribution. the way suggested will be better to visualise better if secondary particles exist.
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