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Need a Silver Sulfide Surface

June 26, 2014

Q. Firstly I am a mechanical engineer, so my chemistry is a little rusty, if you can bear with that you're awesome!

I am trying to create a thin layer of Ag2S on small silver samples, with the goal of creating a layer of Ag2S that has reflective/absorptive properties at certain wave lengths. The deposited film must be of even thickness, with a controllable deposition process.

**METHODS**
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**H2S Chemical Vapor Deposition**
Most commonly Silver is exposed to H2S gas in a humid environment through a CVD process. This process is inherently dangerous, and I would rather avoid it.

**Commercial Tarnishing Agents- Liver of Sulfur**
There are commercially available tarnishing agents, such as [Black Max Oxidizer](http://www.riogrande.com/Product/Midas-Black-Max-Oxidizer-Solutions/331053?Pos=1) solution. This uses hydrochloric acid as well as tellurium. Most commercially available tarnishing agents have an unknown chemical composition, which I fear would cause an impure Ag2S film to form. Am I wrong in this thinking? Controlling deposition rate and uniformity seems difficult with these.

**Solution Based Sulfidation**
One of the easiest methods of forming Ag2S from what I've gathered. Silver is immersed in a heated bath of sulfur [affil links] and a non-polar, aromatic solvent (Toluene is most likely what I'll use). In this process Ag2S and Ag, not sulfur are the main diffusing species.

**Chemical Bath Deposition CBD**
CBD methods of forming Ag2S I am uncertain about. If anyone has any advice on CMD processes that can form controllable Ag2S films that would be great!

Forgive me if I made a few mistakes describing these process, I would like to hear how they are wrong!

What other reactions should I look at for creating an even, controllable layer of Ag2S?

Thanks for reading!

Guy Symonds
R&D - Albuquerque, New Mexcio, U.S.A.