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what is value of "relative permittivity" for gold (au) and aluminum (al) ???

Posted 12 août 2013, 13:48 UTC−4 Version 4.3b 11 Replies

Vivek Saini
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any buddy help me to tell what value should make appropriate result in actuator of

relative permittivity - au ____??
relative permittivity - al ____??
11 Replies Last Post 13 juin 2017, 11:56 UTC−4
Cristofer Flowers
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Posted: 1 decade ago 12 août 2013, 16:14 UTC−4
Try searching for 'dielectric constant of _______'. Here's an MIT link for Au: www.mit.edu/~6.777/matprops/gold.htm
Try searching for 'dielectric constant of _______'. Here's an MIT link for Au: http://www.mit.edu/~6.777/matprops/gold.htm
Edgar J. Kaiser Certified Consultant
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Posted: 1 decade ago 13 août 2013, 02:00 UTC−4
Hi,

the relative permittivity can be very frequency dependent. At low and RF frequencies you can use 1. At optical frequencies it is different and the value gets complex. There should be plenty of material on the web.

Cheers
Edgar

--
Edgar J. Kaiser
emPhys Physical Technology
Hi, the relative permittivity can be very frequency dependent. At low and RF frequencies you can use 1. At optical frequencies it is different and the value gets complex. There should be plenty of material on the web. Cheers Edgar -- Edgar J. Kaiser emPhys Physical Technology
Vivek Saini
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Posted: 1 decade ago 13 août 2013, 13:47 UTC−4
thanks..
thanks..
Szilard Ferencz
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Posted: 1 decade ago 22 janv. 2014, 13:11 UTC−5
Hy! Sorry for disturbing!
I am trying to implement a beam splitter configuration in COMSOL, but I'd like to use Gold, Aluminium or Chrome instead of Silver. The default COMSOL implementation uses Silver, with the relative dielectric constant: epsilon = -16.5-1.06*i. I need some similar values for the other three metals...
Do you have any idea for my situation? I searched all over the internet, but without any results... :( How could I determinate the relative dielectric constant (even if they are complex numbers) for Gold, Aluminium or Chrome?
Please answer!
Best regards: Ferencz Szilard, Technical University of Cluj-Napoca.
Hy! Sorry for disturbing! I am trying to implement a beam splitter configuration in COMSOL, but I'd like to use Gold, Aluminium or Chrome instead of Silver. The default COMSOL implementation uses Silver, with the relative dielectric constant: epsilon = -16.5-1.06*i. I need some similar values for the other three metals... Do you have any idea for my situation? I searched all over the internet, but without any results... :( How could I determinate the relative dielectric constant (even if they are complex numbers) for Gold, Aluminium or Chrome? Please answer! Best regards: Ferencz Szilard, Technical University of Cluj-Napoca.

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Edgar J. Kaiser Certified Consultant
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Posted: 1 decade ago 22 janv. 2014, 13:23 UTC−5
Ferencz,

a little Google search using 'permittivity of gold at optical wavelengths' already yields many hits. Among many others this one: fisica.ufpr.br/jfreire/EstadoSolido/optical%20contstants%20of%20noble%20metals.pdf
which should already answer your questions. It also describes how to measure the complex permittivity. And keep in mind, it is very frequency dependent in the optical domain.

Cheers
Edgar

--
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Ferencz, a little Google search using 'permittivity of gold at optical wavelengths' already yields many hits. Among many others this one: http://fisica.ufpr.br/jfreire/EstadoSolido/optical%20contstants%20of%20noble%20metals.pdf which should already answer your questions. It also describes how to measure the complex permittivity. And keep in mind, it is very frequency dependent in the optical domain. Cheers Edgar -- Edgar J. Kaiser emPhys Physical Technology http://www.emphys.com
Bryan Adomanis
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Posted: 1 decade ago 22 janv. 2014, 18:11 UTC−5
The site refractiveindex.info/ has data files to download, which can easily be input into an interpolation function that defines your frequency-dependent permittivity or refractive index. The 1972 data from Johnson & Christy is available, for example.

-Bryan
The site http://refractiveindex.info/ has data files to download, which can easily be input into an interpolation function that defines your frequency-dependent permittivity or refractive index. The 1972 data from Johnson & Christy is available, for example. -Bryan
Edgar J. Kaiser Certified Consultant
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Posted: 1 decade ago 23 janv. 2014, 04:07 UTC−5
Hi Bryan,

that's a good one, didn't know it so far. Thanks for sharing!

Cheers
Edgar

--
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Hi Bryan, that's a good one, didn't know it so far. Thanks for sharing! Cheers Edgar -- Edgar J. Kaiser emPhys Physical Technology http://www.emphys.com
Farzam Fotovat
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Posted: 9 years ago 13 nov. 2015, 20:20 UTC−5
Hi Edgar,

To find the answer of a similar question, I just came across this post and I would be thankful if you illustrate the following points.

1-While the dielectric constant of the metals is usually reported infinity, how can it be assumed "1" (even at low frequencies)?

2-What is the difference between a metal and vacuum if "1" is considered as the dielectric constant of the metal?

I do really appreciate it if you resolve my ambiguity about this issue.

Cheers,

Farzam
Hi Edgar, To find the answer of a similar question, I just came across this post and I would be thankful if you illustrate the following points. 1-While the dielectric constant of the metals is usually reported infinity, how can it be assumed "1" (even at low frequencies)? 2-What is the difference between a metal and vacuum if "1" is considered as the dielectric constant of the metal? I do really appreciate it if you resolve my ambiguity about this issue. Cheers, Farzam
Leonidas Asimakoulas
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Posted: 7 years ago 13 juin 2017, 09:39 UTC−4

Hi Edgar,

To find the answer of a similar question, I just came across this post and I would be thankful if you illustrate the following points.

1-While the dielectric constant of the metals is usually reported infinity, how can it be assumed "1" (even at low frequencies)?

2-What is the difference between a metal and vacuum if "1" is considered as the dielectric constant of the metal?

I do really appreciate it if you resolve my ambiguity about this issue.

Cheers,

Farzam



Hi I had the exact same question. Did someone solve this for you? Is it ok if we assume a permittivity of 1 for the metals?
[QUOTE] Hi Edgar, To find the answer of a similar question, I just came across this post and I would be thankful if you illustrate the following points. 1-While the dielectric constant of the metals is usually reported infinity, how can it be assumed "1" (even at low frequencies)? 2-What is the difference between a metal and vacuum if "1" is considered as the dielectric constant of the metal? I do really appreciate it if you resolve my ambiguity about this issue. Cheers, Farzam [/QUOTE] Hi I had the exact same question. Did someone solve this for you? Is it ok if we assume a permittivity of 1 for the metals?
Walter Frei COMSOL Employee

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Posted: 7 years ago 13 juin 2017, 10:53 UTC−4
Hello All,
Speaking a little bit more generally towards the underlying questions here, the following page is a good starting point for more in-depth reading on the subject:
en.wikipedia.org/wiki/Dielectric_spectroscopy

Also, we should point out that if you're using the Wave Optics Module or the Ray Optics Module, these do come with a library of several hundred materials (including gold and aluminum) with complex-valued refractive indices as a function of wavelength so that you don't need to look these up.
Hello All, Speaking a little bit more generally towards the underlying questions here, the following page is a good starting point for more in-depth reading on the subject: https://en.wikipedia.org/wiki/Dielectric_spectroscopy Also, we should point out that if you're using the Wave Optics Module or the Ray Optics Module, these do come with a library of several hundred materials (including gold and aluminum) with complex-valued refractive indices as a function of wavelength so that you don't need to look these up.
Leonidas Asimakoulas
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Posted: 7 years ago 13 juin 2017, 11:56 UTC−4
Updated: 7 years ago 13 juin 2017, 11:59 UTC−4
Hi Walter,
thank you for your answer. In my case the voltage that creates the electric field is constant and doesn't vary with time. So I am looking more for a static relative permittivity. In this case would the assumption of 1 be a good approximation for metals? I was using the boundary of my electrode to apply the voltage and then I changed my mind and used the whole domain which had as a result to assign a relative permittivity of 1 for my electrode by default (or maybe I did based on this thread I can't remember). Any suggestions on that would be helpful.
Hi Walter, thank you for your answer. In my case the voltage that creates the electric field is constant and doesn't vary with time. So I am looking more for a static relative permittivity. In this case would the assumption of 1 be a good approximation for metals? I was using the boundary of my electrode to apply the voltage and then I changed my mind and used the whole domain which had as a result to assign a relative permittivity of 1 for my electrode by default (or maybe I did based on this thread I can't remember). Any suggestions on that would be helpful.

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