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- Path: sparky!uunet!olivea!spool.mu.edu!vms.csd.mu.edu!5916RAHMANK
- From: 5916rahmank@vms.csd.mu.edu ( )
- Newsgroups: sci.materials
- Subject: Re: Mat'ls meas. war stories
- Message-ID: <0096668D.8200A2A0@vms.csd.mu.edu>
- Date: 10 Jan 93 22:34:07 GMT
- References: <64400002@hpscit.sc.hp.com> <0096652F.B2E94A20@vms.csd.mu.edu>,<1993Jan9.210224.9365@noose.ecn.purdue.edu>
- Reply-To: 5916rahmank@vms.csd.mu.edu
- Organization: Department of EECE, Marquette University
- Lines: 87
- NNTP-Posting-Host: vmsf.csd.mu.edu
-
- In article <1993Jan9.210224.9365@noose.ecn.purdue.edu>, sankar@lira.ecn.purdue.edu (Mahalingam
- Sankararaman) writes:
- >In article <0096652F.B2E94A20@vms.csd.mu.edu> 5916rahmank@vms.csd.mu.edu
- writes:
-
- In article <64400002@hpscit.sc.hp.com>, markus@hpscit.sc.hp.com (Markus
- Jansons) writes:
-
- Does any one have any interesting or new applications experience
- with maeterials measurments using "electrical" methods.
-
- For example, maeauring capacitance and then calculating dielectric
- constant? What did you use for fixtures or transducers? If you
- have or know of anyone doing or would like to do such measurements
- please advise me.
-
- Sankar:
-
- What do you mean by fixers or transducers. If you just want to measure
- the capacitance, just sputter some electrodes such as platinum and use
- one of the instruments your company (HP) makes to measure the
- capacitance.
-
- But if your aim is to do materials characterization using Impedance
- Spectroscopy, then it is not trivial.
-
- I (Anis) replied earlier:
-
- Perhaps the best way of doing the electrical characterization is
- the use of Impedance spectroscopy a.k.a immittance spectroscopy.
- J. Ross Macdonald's book is an excellent treatment on the whole
- subject including experimental setups.
-
- Sankar writes:
-
- Impedance Spectroscopy, though it is been used for a long time, is
- still in its infancy. McDonalds book is perhaps the only book
- written on this subject. He is also responsible for coining the
- term Impedance Spectroscopy. I recently saw a company (Solartron ?)
- demonstrating ac measurements system using McDonalds methods and
- his software developments. But my concern is treating capacitances
- arising from real materials as ideal Debye capacitance. In fact it
- has been shown real material relaxation is non-ideal and in some
- cases it can be modeled in terms of an empirical formula to account for
- the frequency dependence.
- ================================
-
- A. K. Jonscher published his book "Dielectric relaxation in Solids,"
- Chelsea Dielectric Press, London, 1983, which is basically a
- treatment of impedance spectroscopy. Other than that Macdonald's
- (Not McDonald) book "Impedance Spectroscopy Emphasizing Solid
- Materials and Systems," is perhaps the only book on this subject.
-
- The term 'Impedance Spectroscopy' is in market for a long time.
- What Macdonald coined is the term 'Immittance Spectroscopy' that
- unifies all for complex electrical observables, namely,
- Impedance, Admittance, Capacitance (or dielectric constant) and
- Modulus under a single name. The reason for this terminology is
- the fact that once a frequency dispersion data (aka the immittance
- spectra) measured, it can be represented in any of the above
- four representations.
-
- Immittance Spectroscopy (IS) never treats a measured capacitance
- as ideal Debye response unless the spectra exhibit that, that is
- indeed the case (i.e., a zero depression angle). What Macdonald
- Boukamp, Seitz, and many others have shown is a thing called
- the 'Constant Phase Element' to represent the non-Debye behavior
- of real material systems.
-
- However, the other approach is to approximate a complex response
- by a 'Lumped parameter equivalent circuit.' This has been claimed to
- be reasonable for many materials system by many authors, but again
- the choice should not be just a gross hand waving rather should be
- based on the experimental evidences. Macdonald's book elaborate
- quite a bit on this topic.
-
- Nevertheless, I agree with the statement that IS is in its
- childhood. The main reason for that, perhaps, although numerous
- people used this technique and published paper - not lot of
- Engineers or Scientists wrote book on it. The reason for that, in
- turn, may be the fact that - this technique is mostly instrumental.
- Also only a limited group of materials are well characterized by
- this technique. Or there may be more intricate reasons. I would
- invite others to take part in this thread. I would be interested
- in seeing more discussion on this topic. So long.
-
- -Anis.
-