Recent content by citw

Ok, I think I can figure out the dipole/ionic polarization from here, but I haven't seen anything relating Drude to interface polarization. Do you have any references describing this?

The lower frequency of interface and dipole polarization, in that order, relative to ionic polarization is what I'm having trouble with. I'm not sure why interfacial polarization occurs at the lowest frequency or why dipole/orientation polarization occurs at a higher frequency than interfacial...

Why do polarization mechanisms decrease with frequency in the following order: Space charge/Interface Dipole Ionic Electronic See page 3 in the attached document for reference. Edit: corrected error in wording

The concept of "space charge" around grain boundaries keeps coming up in my reading. I understand that charges tend to build up at grain boundaries, but I'm not sure why. Can someone explain what "draws" charges to boundaries?

Unfortunately, the specific citation for this point is a textbook that I do not have access to.

Maxwell-Wagner polarization is generally described in literature as the polarization of interfaces, such as grain boundaries, with an applied electric field. In the Wikipedia article (http://en.wikipedia.org/wiki/Maxwell–Wagner–Sillars_polarization), it's mentioned that "the charges are often...

This is one of the articles I was reading, and it's referring to the one I just quoted. So conductivity is detrimental to permittivity? I thought you were saying this wasn't the case. Sorry if I'm missing something...

One case is VERY low - about 0.5%. Reportedly, the permittivity increased by an order of magnitude. However, dielectric loss was "mostly higher than 0.1". In this case, the authors mention that "delocalized electron transport related interfacial polarization is probably responsible for the...

Basically, my understanding is that the effect of Nb doping is an increase in the relative permittivity, but also an increase in the dielectric loss due to delocalized electrons created by Nb.

Just to make sure I'm following, polarizability is described by relative permittivity (dielectric constant). The dielectric constant decreases with increasing conductivity, specifically from the imaginary (loss) term. Conductivity is inversely proportional to effective mass, and therefore the...

I think this is where I'm confused... if electrons are weakly bound, I'd take the material to be conductive, and isn't it true that increased conductivity reduces the dielectric constant (via the imaginary term, given for example in the Wikipedia article)?

I think "refuse to" is a bit strong... I was just hoping for a general argument. Here is a link with an example of the case in question: http://www.nature.com/nmat/journal/v12/n9/full/nmat3744.html

Any. I'd like to know how this would ever make sense.

I've read that electron doping in certain materials can lead to higher permittivity (for example, Nb in TiO2). This is a little confusing to me, as permittivity decreases with conductivity (see http://en.wikipedia.org/wiki/Permittivity#Lossy_medium). Can anyone explain this to me? P.S...

We always vent fast entry (load) locks with nitrogen gas. If passivation is the case it makes sense. So basically the point is to keep N2 flowing while the chamber is open to minimize contamination? I usually turn the nitrogen off after getting to atmosphere, so it looks like I've been...