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Mechanical measurements on hard materials

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Top 75 Contributor
14 Posts
Points 158
Bruker Employee
DigestMigrator posted on Fri, May 21 2010 1:19 PM

Hi SPMers,
I intend to measure the elastic properties of hard samples (zirconia, superconductor materials) and I am quite concerned about tip deformation. When using silicon tips, I see that the apex radius changes a lot before and after the experiment by scanning a tip check sample (NiO, Aurora Nanodevices). Then I tried with a diamond tip (a stainless steel cantilever with a whole pyramidal diamond attached at the end,
265nN/nm) but I always indent the material because I cannot apply low forces with such a stiff cantilever. I guess I should use a 20-40nN/nm cantilever with a diamond or diamond coated tip. I have checked the web and I have found several companies that sell this kind of products but the price of the probes ranges from 70 to 300 dollars each and I am a bit disoriented. Have any of you tried this sort of cantilevers to explore the elastic properties of hard materials? Any advice would be really welcome.

Thanks in advance!

--

Gerard Oncins

goncins@ub.edu

Scientific-technical Services
Nanometric Techniques Unit
University of Barcelona

Soler i Sabaris 1
08028 Barcelona (Spain)
phone: +34 93 402 1352
fax: +34 93 402 1398

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Top 25 Contributor
29 Posts
Points 319

Hi Gerald,

An interesting question. The silicon levers with diamonds attached seem like a good choice, maybe another way to go would be to use BLUNT silicon tips, becuase you would expect less damage due to greater contact area. As well as the diamond ones, some companies are offering probes with lower sharpness, more more reprodicuble shapes. THey could be easier to get hold of than the diamond ones,This might help, although I've no experience in using anything other than the steel/diamond combination that oyu mentioned for hard materials.

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Top 10 Contributor
99 Posts
Points 958
Bruker Employee

Hello Gerard and Peter -

  I have used a Veeco Probes (https://www.veecoprobes.com/)  FESP substrate and lever onto which was glued a pyramidal diamond probe from Micro Star (http://www.microstartech.com/) for imaging surface roughness between very tall (80 um) posts (the diamond pyramids were ~100um tall) and they worked quite well.

  Following up on Peter's suggestion for a blunt probe  you might try either a post probe (https://www.veecoprobes.com/p-3230-cdp200a.aspx).   This probe is a cylinder with a flat end, 200nm in diameter.

Or a CD probe such as the CDR300 (https://www.veecoprobes.com/p-3233-cdr-120.aspx).  This probe has a flare, 300nm diameter at the end of the post.   These probes also come in 120nm, 70nm and 50nm flavors.

In these two cases,  the probes are blunted at the end,  the diameter of which is well controlled.  Your application would not be those for which these probes were designed but they may work to suit your needs.

 

Best Regards,

Sean

Top 100 Contributor
9 Posts
Points 77
Suggested by Carl Philippe

Hi Gerard,

Would, given the samples you want to study, a nano-indenter not be a more advised tool than an AFM?

Best regards,

Philippe

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