From: 5916rahmank@vms.csd.mu.edu ( )
Newsgroups: sci.materials
Subject: Re: Mat'ls meas. war stories
Date: 10 Jan 93 22:34:07 GMT
Reply-To: 5916rahmank@vms.csd.mu.edu
Organization: Department of EECE, Marquette University
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.