Sciencemadness Discussion Board

Forget everything else, diamond is the answer!

jpsmith123 - 13-12-2007 at 08:08

According to the attached review paper, doped diamond electrodes may replace MMO, platinum and PbO2.

The paper doesn't explicitly mention suitability for perchlorate production, but it's clearly implied I would say.

Also, U.S. patent app. #20070170070 claims the use of a doped diamond coated anode to make perchloric acid.

Being that graphite can apparently be used as a substrate for diamond deposition, and being that "diamond-like" films can be electrolytically deposited from methanol...this gets me thinking...I wonder if trimethyl borate could be added to the methanol to dope the product with boron?

Attachment: Doped Diamond Electrodes.pdf (804kB)
This file has been downloaded 1094 times


Xenoid - 13-12-2007 at 08:18

Hmmm..... Now all we have to do is erect aerials on our roofs, and wait for a thunderstorm....;)

http://www.sciencemadness.org/talk/viewthread.php?tid=8629&a...

May be we should all try Bob's method after all .... :o

http://members.tm.net/lapointe/Allotropes.html

[Edited on 13-12-2007 by Xenoid]

JohnWW - 13-12-2007 at 12:59

The only problem is that diamond is a very good insulator, in fact one of the best. "Doping" it with small amounts of N or B, incorporated into artificial diamonds, which is a very expensive thing to do, has been done to make semiconductors (n and p type respectively), which operate at voltages about 5 times that for Si or Ge based semiconductors, although because of their cost they are still largely experimental.

I am a fish - 14-12-2007 at 10:14

Actually, not doping synthetic diamond with nitrogen is the difficult bit. Diamonds produced by Gemesis are yellow in colour due to nitrogen impurities. Avoiding this contamination is a major technical challenge.

12AX7 - 14-12-2007 at 14:31

Odd, I heard that they produce N-doped diamonds because they are more expensive.

Edit: The wiki article implies that a vacuum chamber may be all that is needed. Exclude N2, maybe introduce BH3, etc. as desired. (For that matter, B dissolves in Fe. Even easier.)

Tim

[Edited on 12-14-2007 by 12AX7]

I am a fish - 15-12-2007 at 11:23

The impure nitrogen-doped diamonds sell for more, because that is how the gem market is stacked, with coloured gems attracting higher prices. However, technically speaking, the nitrogen doping is a flaw in the process.

dann2 - 15-12-2007 at 12:32

Hello,

I am no diamond expert but I will come in with my 2c's worth. (pun intended).
I think the N doped one sell for more if they are naturally occuring only. If made in the lab (N doped or otherwise) they sell for less.
Lab make diamonds can be told apart from naturally occuring ones by a lab test. Don't think you can tell them apart (the good one's anyways) from visual inspection.

One last gem of info:
Diamond has one of the highest thermal conductivity off all substances. It conducts heat by some weird and wonderful 'lattice vibrations'.

Dann2

Xenoid - 15-12-2007 at 14:34

Synthetic diamonds made by the latest techniques are readily distinguished from natural stones by optical microscopic examination, they are FLAWLESS. Natural stones have all sorts of lattice defects and occluded minerals.

I am still waiting for the diamond coated frying pans, which were touted about, several years ago... :o

12AX7 - 15-12-2007 at 20:40

It also has an anomalous heat capacity, something Einstein and Debye theorized on early in the 20th century. The best explanation is a lattice of relatively stiff oscillators, linked to each other such that one can analyze the exchange of energy as wave particles -- phonons -- bouncing around inside, having energies from about zero up to a cutoff, such that the wavelength of these oscillations must be less than the corresponding distance between atoms.

Diamond is composed of a rather stiff lattice; as a result, these oscillators have steep energy levels and don't store much energy (as heat) at low temperatures. As a result, diamond has significantly less heat capacity than most other materials at room temperature.

Statistical mechanics is interesting, if mathematically intensive. I now know the formulas and derivations explaining this, though it's certainly above and beyond the topic of this thread (and probably of even less interest to most here!).

Tim

chloric1 - 16-12-2007 at 07:26

We only need a plasma at 2200 to 2800. Comeon it is not that hard to do in the garage.:P


Seriousy though, microwave energy was mentioned and someone that reads here who has telecommunication expertice might be able to make a microwave gun that can be tuned to energize some organic vapors. Microwaves are definately able to heat certain things up to insane temperatures in a hurry.


Silicon as a substrate? Wow! That's just crazy cool! Of coarse not practical for large electrodes but it would nice for a pocket model. I would like to known in my neighborhood as"The guy who makes doped diamond silicon substrate anodes" I wonder how well they could sell on ebay.:cool:

Twospoons - 16-12-2007 at 14:29

Of the diamond CVD papers I've seen, the most common (and accessible for us) method is simply a hot tungsten filament in a low pressure atmosphere of H2, CH4, CO2. Even the pressure requirements are not difficult ( 1or 2 torr IIRC). Typical substrates were tungsten sheet rubbed with diamond dust (for nucleation). Deposition rates are slow - μm per hour - so it would likely take a week or two to build a working coat.

jpsmith123 - 16-12-2007 at 15:26

I've seen a patent claiming that you can use water/alcohol vapor instead of H2 & CH4.

But anyone with a high voltage DC power supply can try the electrolysis of methanol as per the attached paper.

Attachment: Electrolysis of Methanol.pdf (132kB)
This file has been downloaded 1526 times


Nixie - 17-12-2007 at 04:45

Quote:
Originally posted by jpsmith123
I've seen a patent claiming that you can use water/alcohol vapor instead of H2 & CH4.

But anyone with a high voltage DC power supply can try the electrolysis of methanol as per the attached paper.

I wonder if there's any benefit to going for a higher voltage (I can do about 150 kV at the suggested 20 mA current density), at least in terms of being able to deposit a thicker film. The only thing I'm missing to try that experiment is the HF for cleaning the substrate (and I have no clue how to obtain any). And how would one go about doping such a film?

[Edit:] By the way, I'm still waiting for you to answer my message from a long time ago :|

[Edited on 17-12-2007 by Nixie]

jpsmith123 - 17-12-2007 at 05:54

I'd bet that you could use a graphite substrate with the surface prepared by anodic etching in NaOH, Na2CO3, Na3PO4, etc. Maybe electrocleaned and hydrided titanium would work, too.

IMO, one interesting experimental aspect would be to see if the coatings could be made conductive by adding small amounts of, say, methyl borate or some other boron containing compound to the methanol.

(BTW sorry about the lapse. I was forced to move a few times, unexpectedly, and I had little or no internet access and no access to my files, etc., for a few months. Are you still involveed with that project?)

Nixie - 17-12-2007 at 14:46

I am; not in a hurry as work is busy at the moment, but I hope to get back to it early '08. It'd help if I knew what else I'd need to purchase so I watch out on eBay and surplus places.

jpsmith123 - 8-1-2008 at 07:10

I'm still thinking about this, especially since none of other efforts have yet produced a reliable perchlorate anode.

Ok here's the idea:

It seems that many places are selling diamond powder on line...I've seen it for a few dollars per gram. I would guess that at least some of these powders are "contaminated" with something else e.g. nitrogen, and are therefore conductive.

In several of his patents Beer talks about "rolling" the noble metal oxide into the titanium, or electrophoretic deposition, or just painting on an oxide slurry, followed by baking at high temperature.

According to several patents, titanium hydride can be used to create a bond to diamond; just mix the hydride with diamond and heat to decompose the hydride (preferably in an inert or a reducing atmosphere).

So why not take a piece of Ti, hydride it, coat it with diamond powder, and bake to create the bond?

[Edited on by jpsmith123]

-jeffB - 8-1-2008 at 07:19

If electrolyzing methanol at kilovolts is annoying, what about DMSO at 150V?

http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=n...

-jeffB - 8-1-2008 at 07:24

Quote:
Originally posted by Xenoid
I am still waiting for the diamond coated frying pans, which were touted about, several years ago... :o


I got to try one of these out some years ago -- a friend of mine ran a materials lab, and one of their collaborators was looking at starting up a company to make them. It was disappointing. It was a lot stickier than Teflon, or even well-seasoned cast-iron, and it certainly appeared to be scratched by stainless-steel utensils, although I suppose I may just have been leaving stainless-steel streaks on it. There is something cool, though, about the idea of serving breakfast out of a diamond skillet...

microcosmicus - 8-1-2008 at 07:48

Assuming you have some sort of furnace which can achieve the required
temperature in an atmosphere which doesn't burn your diamonds, this
sounds like something interesting to try. This is the sort of procedure used
to make diamond files. At any rate, it would be interesting to be able to do
this at home --- I would certainly be curious to know how your attempts turn
out since high temperature stuff interests me.

As for use as an anode, an obvious point is that the substrate holding the
diamond is metal (titanium in this case) and therefore also conducts so,
if your purpose were to create an anode in which the conducting surface
were purely diamond, this would not do. Rather, you would have a mixed
titainium-diamond electrode. Looking at one of my diamond files, I see that
something like half the surface area is metal substrate, To have only the
diamond be in contact with the electrolyte, you would somehow have to
cover the titanium which holds the diamond grains in place with an insulator.
Maybe this could be done by some process like painting the electrode with
an insulator, then rubbing out the high spots so the diamonds show through
or maybe you could cover the Ti with a non-conductive oxide layer by anodizing it.

[Edited on 8-1-2008 by microcosmicus]

jpsmith123 - 8-1-2008 at 08:11

@-jeffB: Thanks for the reference. I've posted a request for the full paper.

@microcosmicus: Theoretically it's ok to have titanium exposed to the electrolyte, as it forms a self-protecting oxide layer. (That's why titanium and the other so-called "valve" metals are preferred as substrate materials).

microcosmicus - 8-1-2008 at 09:53

@jpsmith123
In that case, what about stainless steel --- an oxide coating is what
makes it stainless, after all. Or is titanium oxide more resistant to
the stuff found in chlorate cells than chromium oxide? Diamond in a
SS substrate is quite easy to find in the form of diamond files, laps,
knife sharpeners, etc.

Duh -- using the stuff as an anode would automatically anodize it,
wouldn't it :)

[Edited on 8-1-2008 by microcosmicus]

12AX7 - 8-1-2008 at 10:23

I'm learning every day, more and more, just how fucking resilient TiO2 is. Even to fluorides. . .

Stainless does not compare, period.

Tim

Here's another interesting paper.

jpsmith123 - 8-1-2008 at 12:47

This paper describes some diamond coated anodes. Note the current densities they tested them at.

"However until now, diamond has not been introduced in electrochemical applications because of the limited availability of diamond for large-area electrodes. In the last years large-area chemical vapour deposition (CVD) of polycrystalline diamond films has been developed, yielding deposition areas of up to 0.3 m2 on metallic and ceramic substrates. These boron doped conductive diamond electrodes are semiconductor electrodes with a
microcrystalline structure and comparatively rough surfaces. Diamond-coated electrodes are chemically, mechanically and thermally very resistant (4) and show no significant corrosion even under high electrochemical load (5, 6). Galvanostatic investigations show no detectable changes of the electrodes for example after several hours in a solution of NaF in concentrated nitric acid at 50 °C (6) or in sulphuric acid (7). Over several weeks at 2 to 10 A cm-2 and thousands of Ah cm-2 the electrochemical activity of these diamond electrodes remains also constant in contrast to other conventional carbon electrodes (8)."

Attachment: Paper.pdf (2MB)
This file has been downloaded 2847 times


Nixie - 8-1-2008 at 14:02

What is the maximum temperature diamond can withstand in air for a prolonged period of time? I platinum-plated my tunsten plasma electrodes, but I'm wondering if diamond would last longer or allow a higher temperature.

[Edited on 8-1-2008 by Nixie]

jpsmith123 - 8-1-2008 at 14:57

IIRC it starts to oxidize around 700 C or something like that, so you're probably better off with platinum.

What'd you do, electroplate the platinum onto the electrodes?

Nixie - 8-1-2008 at 15:22

Plated platinum black with some lead oxide in the chloroplatinate and then sent to someone bake in inert atmosphere to diffuse the plating into the substrate as per a patent that was posted here a while back.

Electrodeposition Of Diamond-Like Films

jpsmith123 - 8-1-2008 at 17:26

I found an interesting abstract of a thesis (couldn't get the paper though):

Diamond-Like Carbon (DLC) films were successfully deposited on the ITO substrate by electrodeposition technique. This method has several advantages in terms of low cost, rapid growth rates and simple setup. Electrodeposition of DLC thin film was carried out at low DC potential by using a mixture of acetic acid and DI water as electrolyte. The Raman spectra showed two peaks located at 1350cm-1 and 1580cm-1, which were the characterized peaks for DLC films deposited on ITO substrates. By varying the experimental parameters such as the deposited DC potential, distance of electrodes, and the concentrations of solution, the growth mechanism of deposition process was investigated, and the best quality of DLC films was also achieved. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to make insight into accurately the surface morphology of DLC films related to deposited parameters
In addition, according to the experimental results, it indicates that the quality of the DLC film was improved as deposited at higher DC voltage. Finally, to demonstrate the effect of annealing on the interfacial characteristics the C-V and G-V curves of MIS structures are the further works.

http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=e...

So, all you need is some distilled vinegar and a low voltage power supply? That sounds like my kind of experiment. Too bad I couldn't download the full paper.

And here's another interesting abstract:

doi:10.1016/S0009-2614(01)01040-5
Electrodeposition of diamond-like carbon films in organic solvents using a thin wire anode

Hao Wang, 1 and Masahiro Yoshimura,
Materials and Structures Laboratory, Tokyo Institute of Technology, Nagatsuta, Midoriku, Yokohama 226-8503, Japan

Diamond-like carbon films (DLC) have been electrodeposited on silicon substrates in organic solvents using a thin tungsten wire anode under high potential. During the deposition, if the applied potential is sufficient enough, the spark could be observed even by the naked eye. It has been manifested that this method could produce an extreme environment which is favorable to form much more sp3 bonded carbon atoms compared with conventional electrolysis.

#####################################

And here's yet another, apparently related, thesis:

In the early years, DLC films was deposited at high voltage applied by electrochemical method. In this study, DLC film was deposited alternatively at low voltage applied using electrodeposition. The ITO glass substrate was used as the cathode, and graphite sheet was the anode. The electrolyte is a mixture of acetic acid with DI water. The applied voltage was mere 2.1 volt during the electrochemical process.
For investigating the structure of deposited films, the deposited DLC layers were characterized by Fourier transform infrared (FTIR), Scanning electron microscope (SEM) and Raman spectrometer. The SEM results show that the DLC films have a rough surface and their roughness increased with longer in deposition time as well as raise applied voltage. The Raman spectra shows distinct broad characteristic peaks at ~ 1336 cm-1 (D-peak) and ~ 1601 cm-1 (G-peak), which indicate the disordered graphite-like structure and the graphite structure, respectively. While the bond angles occur to bend or the increase the content of sp3 bonds in DLC film, both the G-peak and the D-peak shift to the lower wave numbers. Peaks at ~ 2956 and ~ 2917 cm-1 found in FTIR measurement were used to recognize the existence of sp3 and sp2 combined carbon atoms in the films. Based on above results, it could conclude that the DLC film could be prepared by electrodeposition under low applied voltage.

http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=e...

Once again unfortunately it seems the full paper is not available for download.

[Edited on by jpsmith123]

dann2 - 8-1-2008 at 20:24

Hello,

The Vinegar and battery sounds good!!

If you put in a request in the reference section someone may be able to get it for you.

One wild idea I was thinking today was this. (It is off topic in a Diamond Anode thread though ).
If you were to use a solvent other that water, an alcohol perhaps, would this give any advantages when making (Per)Chlorates. There would be no problems with O2 evolution, perhaps less anode corrosion, hugh yields of (Per)Chlorate :P etc etc. I presume the solutions would be conductive or would they?
Cost and inflamability comes to mine for disadvantages.

Think it's time for another drag from by pipe...............

Dann2

jpsmith123 - 9-1-2008 at 04:58

Hmmm, well the oxygen for the perchlorate comes from the water so I don't know what would happen with alcohol.

As far as bizarre new ideas are concerned, I don't think it would be practical, but it would be academically interesting to me to see what would happen if you flow NaClO3 solution over a piece of anodized Ti out in the sun. I wonder if you could photocatalytically oxidize the chlorate to perchlorate that way? Given that you'd be depending on wavelength content less than 400 nm (you'd only have a useful solar flux of a few tens of watts/m^2 or something like that), and given that the process isn't very efficient in the first place, you'd probably wait a long time for a few ounces of ClO4.

BTW someone uploaded the paper I requested (DLC films from electrolysis of DMSO) in the reference section and it's an interesting read. It's seems clear that these DLC films can be made at home. I'm also trying to get the theses I referenced. It seems our problem may be trying to dope the films to make them conductive.

######################################
Edit:

It seems DLC films have been electrodeposited from many different things. I wonder, what about trimethylglycine (TMG) dissolved in distilled water or alcohol? I'm going to have to start experimenting here pretty soon.

[Edited on by jpsmith123]

######################################
Edit:

Just for the hell of it I took a piece of Ti that I had previously hydrided and stuck it in a stainless steel cup filled with about 300 ml of distilled water. With the Ti as cathode and the cup as anode and the power supply maxed out at 30 VDC, I was reading about 150 uA.

Then I took about 30 grams of trimethylglycine and dissolved it in the distilled water, and the current increased to about 4.5 mA.

I'll let it sit there all night and see if the current changes at all. If it's depositing a poorly conducting DLC layer, I suppose I should expect the current to decrease.

I'll have to get some distilled vinegar tomorrow and try that too. Too bad the theses involving vinegar aren't available.

[Edited on by jpsmith123]

The vinegar might actually be making a DLC.

jpsmith123 - 10-1-2008 at 13:19

Using vinegar as electrolyte, I noticed an effect that makes me think it could be working.

I started at 2 vdc and increased the voltage incrementally while watching the current.

Every time I increased the voltage somewhat, the current would also increase, but then it would fall off a little bit. For example, if the current initially went up by 50 uA, then, over the course of a minute or so, it would fall off by 10 to 20 uA.

As I took the voltage higher and higher, this effect was no longer noticeable as I had to switch from a uA to a mA meter, and I think the "hydrogen current" was swamping the "diamond current" at this point.

I didn't notice this subtle effect when I used the trimethylglycine solution. I'm guessing that 30 volts isn't enough for this electrolyte.

What I want to know, is, how can I easily tell if the "grey discoloration" now on the Ti is a DLC or is it TiH2?

JohnWW - 13-1-2008 at 13:47

Besides doped diamond-like carbon thin films being a suitable coating for electrodes to prevent corrosion in electrolysis, another use for diamond (or diamond-like boron nitride) films, although not necessarily doped, would be as an extra-hard coating or cladding for metal-cutting power tools, such as drill bits and saw blades and the bits used in lathes and milling machines. Some of them are already plated or clad with titanium, but even this, along with tungsten carbide chips, may not be hard enough to cut some materials.

jpsmith123 - 13-1-2008 at 13:58

The other day while looking to see if boron-doped-diamond (BDD) powder was available for sale anywhere, I came across an interesting paper showing that BDD was actually a better coating for cutting tools than straight diamond. If I can find it again I'll upload it.

jpsmith123 - 17-1-2008 at 19:16

Well I tried to duplicate the DLC synthesis by way of low voltage electrolysis of dilute acetic acid, as per the paper by Gupta et al., to no avail. (At least I don't think anything happened). The only difference was that I used titanium as a substrate rather than silicon, as I had no silicon available.

Some papers on the subject reported fairly decent DLC growth, not over bare Ti, but over a native TiO2 layer on Ti...which is what I thought I had...yet still no results.

Before giving up I intend to try the HV electrolysis of methanol as soon as I get set up for it.

not_important - 18-1-2008 at 01:00

If the paper you are talking about is titled Low voltage electrodeposition of diamond-like carbon films, they used conductive SnO2 on glass, not silicon.

The films were thin, no more than a micrometer in thickness. How were you testing to see if a film had formed? Did the set-up have a similar I-V curve to theirs?

jpsmith123 - 18-1-2008 at 05:17

Sorry my mistake, you're correct, Gupta et al. used SnO2 on glass; the experiments with methanol used silicon substrates. (I've been looking at so many papers lately, my head is spinning).

If I had to guess, what I think went wrong in my experiment is that my drug store distilled water was too conductive. At an applied voltage of 4.1 volts, my current density was much higher than theirs, and it didn't fall off with time, as it apparently should have.

They reported 0.1 mA/cm^2 (@4.1 V), whereas I was seeing almost 1 mA/cm^2. Thus I probably had way too much hydrogen, which etched the substrate clean.

For purposes of analysis, I started with two lengths of Ti, cut from the same piece; unfortunately all I could do was compare them visually, and compare the electrical resistance with a DMM. Doing this, I saw no difference whatsoever.

Edit:

I wonder where can I get some ultrapure deionized water cheaply?

[Edited on by jpsmith123]

dann2 - 18-1-2008 at 16:29

Hello,

Used to work (some say Dann2 would'nt work on a F*C&%^G battery) in a factory where they made water for injections. THAT stuff was clean. Way beyond deionized.
You can probably purchase it from a chemist or vetinary source.
One place you can get it for free (don't laugh) is in a needle exchange (or addicts). They dole it out in small 'one shot' bottles.
The procedure is this:
Throw on a pair of what this guy has on :cool: .
Enter exchange.
In a very strained voice you say "What's the story man, what's the story man" etc etc.
May help to take a handful of second hand syringes.
:P:cool::(:):o:D;):mad: (that could cover all persuasions/points of view) :D

Dann2

jpsmith123 - 18-1-2008 at 17:12

Hmmm you seem to be very familiar with that method, Dann2...verrry familiar :o.

Xenoid - 18-1-2008 at 17:41

@ jp

I believe the "usual" way to produce ultrapure water is to distill it using a low temperature (non-boiling) quartz glass still. I helped set up an isotope lab many years ago and that was part of the "equipment". The still is heated with a ?100W light bulb, and charged with normally distilled and deionised water. The important thing is that droplets of water from boiling are not carried over. An ordinary glass still operated at low temp would probably work.

How about a bowl of purified water, with a sheet of gladwrap on it and a weight in the centre to drip the condensation into a small container, also in the bowl. Put it out in the sun!

jpsmith123 - 19-1-2008 at 12:01

Those sound like some good ideas, Xenoid, but for right now I would like to just buy some somewhere, if possible.

JohnWW - 3-3-2008 at 19:46

I have just received the following periodic email, on solid-state physics and materials science, from Japan, to which I am subscribed. Some articles linked in it, which can be viewed for free, are highly relevant to growing diamond films, and diamond semiconductors (doped with B or N):

From: ipapAlert@ipap.jp
To: johnww@...........
Subject: APEX/JJAP E-mail Alert; March 4, 2008
Date: Tue, 4 Mar 2008 12:14:05 +0900

APEX/JJAP E-mail Alert; March 4, 2008 by Institute of Pure and Applied Physics
http://www.ipap.jp

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Ferroelectric Polarization Reversal by a Magnetic Field in Multiferroic Y-type Hexaferrite Ba2Mg2Fe12O22
by Kouji Taniguchi, Nobuyuki Abe, Shintaro Ohtani, Hiroshi Umetsu, and Taka-hisa Arima
URL: http://apex.ipap.jp/link?APEX/1/031301/

Lowering Threshold by Energy Transfer between Two Dyes in Cholesteric Liquid Crystal Distributed Feedback Lasers, by Koji Sonoyama, Yoichi Takanishi, Ken Ishikawa, and Hideo Takezoe
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Optical and Conductive Characteristics of Metallic Single-Wall Carbon Nanotubes with Three Basic Colors; Cyan, Magenta, and Yellow by Kazuhiro Yanagi, Yasumitsu Miyata, and Hiromichi Kataura
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Influence of Substrates on Initial Growth of Diamond-Like Carbon Films by Nobuto Yasui, Hiroshi Inaba, and Naoto Ohtake
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Near-Surface Defects in Boron-Doped Diamond Schottky Diodes Studied From Capacitance Transients
by Pierre Muret, Julien Pernot, Tokuyuki Teraji, and Toshimichi Ito
URL: http://apex.ipap.jp/link?APEX/1/035003/

Nitrogen Gas Flow Driven Unintentional Incorporation of Al during the Growth of Dilute Nitride Semiconductor by Plasma-Assisted Molecular Beam Epitaxy, by Shudong Wu, Masakazu Kato, Masayuki Uchiyama, Kotaro Higashi, Fumitaro Ishikawa, and Masahiko Kondow
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Correlation Imaging of Magnetic Recorded Patterns and Grain Structures of Perpendicular Magnetic-Recording Media, by Yoshio Takahashi
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[Edited on 4-3-08 by JohnWW]

dann2 - 10-4-2008 at 19:26

Hello,

And another.
Hope they have not been uploaded before.

Dann2

Attachment: doped diamonds2.pdf (2MB)
This file has been downloaded 639 times


Look at this!

jpsmith123 - 29-1-2009 at 07:21

Apparently you can now buy, online, from their "CVD diamond eshop" (LOL!) a piece of polycrystalline "electrochemistry grade" CVD diamond.

Maybe this is the perchlorate "Holy Grail"? I think I might have to order some to find out...

http://www.e6cvd.com/cvd/page.jsp?pageid=161

dann2 - 29-1-2009 at 11:26

Hello JP,


That's an interesting find and it would be an even more interesting purchase....
There is some reading under the 'Education' link on the page too.
I have attached an article from the link.

Must do some reading up on these Diamonds.

Dann2

Attachment: History of CVD diamond.pdf (17kB)
This file has been downloaded 921 times


Xenoid - 29-1-2009 at 11:46

Interesting find jp.....

.....but it's bloody expensive, more than I paid for my Pt coated electrode and it's only 1 cm square. How will it be possible to make an electrical connection? I suppose it could be bonded onto a Ti strap somehow. Why don't they coat some inert metal with this stuff, to make it more practical?

jpsmith123 - 29-1-2009 at 12:06

It's too bad they don't have a bigger size available "off the shelf".

Anyway, I too am wondering how you would mount it and/or make electrical contact with it.

Maybe it could be mounted as a "window" somehow, sealed against the wall of the cell with a viton o-ring, with a piece of wire epoxied to it?

Let's say its resistivity is 0.1 ohm-cm, then with a thickness of 0.06 cm and 1 cm^2 area, its resistance would be about 0.006 ohms...so it should be able to handle a few amps I would say.

I'm still trying to find type "IIb" conductive diamond grit somewhere...that's the stuff I would like to experiment with. I can't believe that nobody is selling it yet.

Edit:

I bet if you had a piece of this stuff to start with you could add to it with electrodeposition from methanol or DMSO or something.

[Edited on by jpsmith123]

chief - 29-1-2009 at 19:58

What about plain old silicon: Does it dissolve in an perchlorate-cell ? Does it form an isolating SiO2-Layer ?

As long as Si has the same structure as Diamond (which it has), it might be useful for the purpose ? Someone might slaughter an old Diode or something, and try out ...

If it works: Standard solar-cells might be abused (also coated with SnO2); question only would be, if it wouldn't exhibit nonconducting Diode-Properties in the wrong direction: Then the SnO2 would have to be coated with some metal (for contacting), and the back of the solar cell would have to be used ... ; There would be a Power-consuming voltage-drop, but this could be come by usind the Si-electrode for rectification directly ...



[Edited on 29-1-2009 by chief]

chief - 29-1-2009 at 20:07

Next post, different idea: Electrodeless electrolysis can be applied using a high voltage, and corona-discharging onto the electrolyte: The current flows, but the electrode isn't immersed in the electrolyte, and therefore not subject to the agressive chemistry therin.
A long time ago I electrolyzed a solid CuSO4*xH2O-crystal like that, using the anode-voltage from a small TV, limiting the current by a 5 MOhm-resistor to maybe 5 mA. After a while it could, under the microscope, clearly be seen, that elementary copper was made.

This might maybe useful for the diamond-deposition-elecrolysis ; also maybe an electron-beam-chamber might be used ... .



[Edited on 29-1-2009 by chief]

Electrolytic DLC over SnO2

jpsmith123 - 7-2-2009 at 13:40

Here's an interesting paper re DLC on stainless steel with an intermediate layer of SnO2.

Attachment: 01.10_m._roy_a.k._dua_a._english.pdf (805kB)
This file has been downloaded 463 times


dann2 - 7-2-2009 at 14:06

Hello,

As far as I can see, DLC is a nonconducting coating and not the same as diamond. (see page 63 below graphs seems to suggest this too.) Could be wrong though.
I worked in a place where they deposited DLC films and they were totally Nonconducting. :(

Dann2


[Edited on 8-2-2009 by dann2]

Xenoid - 7-2-2009 at 15:58

Quote:
Originally posted by dann2

I worked in a place where they deposited DLC films and they were totally conconducting.


LOL, "conconducting" is that a new type of conduction Dann2? Or is it actually nonconducting but you have managed to convince others that conduction is occurring! :D

dann2 - 7-2-2009 at 17:32

.............perhaps I should read my own posts sometimes........
Make no mistake, the ones I made were definitely conconducting &reg ones :P

DLC on Si below:

Dann2

DLC on Si.JPG - 12kB

jpsmith123 - 8-2-2009 at 21:58

Hello Dann2,

I'm not sure exactly what you're getting at when you say that DLC films "[are] not the same as diamond".

Anyway, there is a brief general explanation of DLC here.

As far as the conductivity goes, you're right, diamond itself (except for "type IIB") and straight DLC films will be nonconducting. We would need to add a boron compound to the electrolyte to solve that problem.

As soon as I can get my hands on a suitable HV power supply, I plan on doing some experiments.

DLC (Amorphous, 7 types) versus Crystaline (one type??) Diamond coat

dann2 - 9-2-2009 at 11:30

Hello JP,

Quote:
Originally posted by jpsmith123
I'm not sure exactly what you're getting at when you say that DLC films "[are] not the same as diamond".
....................


As far as I can see there seems to be DLC (7 different forms all amorphous) and then Diamond films (crystalline)
Quote from here.
"Diamond-like carbon (DLC) is an umbrella term that refers to 7 forms of amorphous carbon materials that display some of the unique properties of natural diamond. The German Fraunhofer - IST institute has organized them into the chart form seen in this page background."

The chart here seperates the DLC from the 'Diamond films'.

Perhaps I am splitting hairs but I think you need the actual Diamond films (not amorphour) for Electrodes.
Perhaps as you say doping DLC will make it suitable.

The 'Diamond film' (crystaline not amorphous) needs to be doped for conductivity.

It should be noted that I know little or nothing regarding the DLC/Diamond coat stuff so I am close to guessing and perhaps splitting hairs.

The Diamond stuff is definitely an interesting avenue.
Did you try to obtain the Thesis (way above) regarding Acetic + HV supply?
I emailed the Author + email at bottom of Thesis page just now. Will see if they reply.

edit:
Attached a paper from Ref. Section.
Hope I am not clogging up the board with papers or should I link to it in the ref. sec. instead of attaching?
It is not a very hands-on or 'useful to us' paper me thinks.
HAVE A GOOD (BEDTIME) READ ANYWAYS!!!!!!!!!!

Cheers,
Dann2

[Edited on 10-2-2009 by dann2]

Attachment: Diamond on Ti for ElectroChem.pdf (1.4MB)
This file has been downloaded 644 times


tentacles - 9-2-2009 at 23:13

Quote:
Originally posted by jpsmith123
As soon as I can get my hands on a suitable HV power supply, I plan on doing some experiments.


Well, check this one out:

http://cgi.ebay.ca/Hipotronics-HV-DC-Power-Supply-850-30-Hig...

jpsmith123 - 10-2-2009 at 10:52

@Dann2

From all I've read I think what we're concerned with is the "quality" of the film (i.e., the relative amounts of SP3 vs SP2 bonded carbon), the adhesion to the substrate, and the conductivity.

The paper recently posted here regarding electrodeposition of DLC films from ethanol seems to demonstrate a relatively "high quality" film (apparently comparable to that of plasma or hot filament CVD deposition methods), at 300 volts and millimeter spacing.

Moreover, from all I've read, it seems that doping with boron, in addition to increasing the conductivity, will also tend to increase the quality, the adhesion, and the deposition rate of the film as well.

The main question I have right now is: What substrate do we use? Several papers (including the one you've recently posted) point out the difficulty encountered with putting DLC on Ti, but these papers have all been concerned with CVD methods where the substrate is coated at a high temperature. We may not have a problem putting DLC film on Ti at room temperature. Also, what about if the Ti surface is hydrided?

Lastly, if electrodeposition methods can build up a coating rapidly (as I would think, especially since they're presumably being made conductive with boron doping) maybe we don't need a substrate? If it's possible to make a piece thick enough to stand alone, maybe an electrical contact can be electroplated onto it?

@Tentacles

Although the specs for that supply aren't explicitly stated in the ad, in looking at the panel meters, it seems the voltage is too high and the current too low. I think a max voltage in the range of 500 to 1000 volts at 100 ma or so current would be ideal.

Twospoons - 10-2-2009 at 18:12

Why not the obvious substrate : graphite !

Xenoid - 11-2-2009 at 16:49

Quote:
Originally posted by jpsmith123

Although the specs for that supply aren't explicitly stated in the ad, in looking at the panel meters, it seems the voltage is too high and the current too low. I think a max voltage in the range of 500 to 1000 volts at 100 ma or so current would be ideal.


You should look for electrophoresis power supplies! I picked up an LKB 2103 a few months ago, it was about NZ$100 (US$50) and although about 25 years old is in excellent condition. They would be cheaper in the US for sure.

It has constant power, voltage and current (110W, 0-2KV and 0-200mA) ideal for high voltage electrolysis.

jpsmith123 - 12-2-2009 at 10:17

Hello Xenoid,

I've actually been looking for electrophoresis power supplies. I've seen some units manufactured by "ISCO" (e.g., model #493, #494) for sale at some surplus places (online), but I can't find any specs, user manuals, etc. for them.

BTW, have you tried electrolyzing any methanol, ethanol etc., at high voltage yet?

dann2 - 12-2-2009 at 14:00

Hello,
See here for some info. on DLC with Pt in it. They seem to say that DLC is not electrochemically active (like it cousin crystalline diamond).
The info. is on page 108

See also page 97 (same book) for some stuff on BDD.
And page 88 and page 72............
FFS Dann2 just post the whole book!!!!!!!!!!!

Sorry but I am scanning through book and posting at the same time.
To sum up> This book is worth taking a look at.
Wonder can anyone over in the (glorious, heroic and galant) Ref. Section get this book.

Intro. (from page 108) in jpeg below.


Dann2

[Edited on 12-2-2009 by dann2]

DLCWITHPT.jpg - 63kB

jpsmith123 - 12-2-2009 at 14:31

Hmmm I'm not sure I understand precisely what they mean. Are they merely pointing out that straight amorphous DLC is not a conductor...ipso facto it is not "electrochemically active"? But crystalline diamond is also an insulator, no? I'm confused.

dann2 - 12-2-2009 at 15:08

Hello JP,

Don't know I will have to say.
See here:
http://materials.web.psi.ch/Publications/Publ_MatDev_files/2...
Section 22.5 page 581

It seems to say that DLC is electrochemically active. It's info. from 1997. They are only referring to DLC being used as electrodes as opposed to an Anode for actually making stuff.


Thesis here:
http://materials.web.psi.ch/Publications/Publ_MatDev_files/T...
Not much use to us (after having a look at it). There is some rather complicated machinery for DLC coating ..............

Patent here:
here saying (examples close to bottom):
"The DLC can be made such that it is more electrically conductive by changing the deposition conditions, thereby making the DLC coated mesh useful as an electrode for electrochemical applications. Additionally, DLC can be doped with boron, phosphorus, other metals and non-metals."

Google search here
second from bottom:
...... Thus, we conclude that DLC is electrochemically inactive in itself.........

Will look for this paper (book?) in ref. section.
EDIT:
Link to this book here
Thanks to gsd for that one.


Attached is a paper on DLC Films doped with Phosphorous

Dann2

a rather rambling post

[Edited on 13-2-2009 by dann2]

[Edited on 13-2-2009 by dann2]

Attachment: P doped dlc.pdf (460kB)
This file has been downloaded 1099 times


jpsmith123 - 14-2-2009 at 08:09

Well Dann2 I find that the more papers I look at, the more confused I become.

IMO the most promising paper so far is the one by Sreejith et al. regarding the "low voltage" deposition of DLC from ethanol, where the resulting SP2 fraction was 7.1% (@ 300 volts and 1 mm spacing). However it would be nice to see somebody else duplicate these results.

Anyway, assuming that adding some ethyl or methyl borate or even a little boric acid would dope the DLC with boron and make it conductive, well this might be just what we're looking for.

As I see it the biggest unknown is the choice of substrate material...I think we're at the point where some experimenting is in order...now if I could just find a decent yet cheap adjustable HV power supply...

Aqua_Fortis_100% - 14-2-2009 at 19:35

Hi,
just to add my two cents on references:

http://www.scielo.br/pdf/jbchs/v17n4/30537.pdf

http://www.scielo.br/pdf/mr/v2n2/0016.pdf

http://www.scielo.br/pdf/qn/v28n2/23655.pdf

http://www.scielo.br/pdf/jbchs/v15n1/a04v15n1.pdf

I wanted right now to attach the thesis "Estudos da eletroquímica do diamante dopado com boro e da sua superfície modificada com catalisadores para a oxidação de metanol e etanol" ("Studies of boron-doped diamond eletrochemistry and of their surface modified with catalyst for the methanol and ethanol oxidation" - with english abstract), but it seems too big and painfull slow to load, so to get the pdf go to: http://www.teses.usp.br/teses/disponiveis/75/75131/tde-11042... , click on "GiancarloRSalazarBanda.pdf " in the bottom , mark the box "Eu li e concordo com as condições acima." ("I have read and agreed with abovementioned conditions") and then in "Condordo".

If anyone wants a quick translation of any part in these portuguese documents, let me know although I dont guarantee "100%" in translation since there are very technical terms in portuguese in these documents that are very hard to find a equivalent in english speaking.

[Edited on 15-2-2009 by Aqua_Fortis_100%]

Blind Angel - 17-2-2009 at 20:51

Found something that could be interesting, I have no idea if Lonsdaelite is conductive but this could be interesting to look at.

http://en.wikipedia.org/wiki/Poly_(hydridocarbyne)

A polymer which take a Diamond-Like form when heated to 110°C under Argon at standard pressure.

Interestingly it can be synthesized by electrolysis of chloroform.

jpsmith123 - 18-2-2009 at 13:42

@Blind Angel:
Thanks for that information...I've never heard of anything like that before. It's fascinating. I wonder how easily it could be boron-doped?

@Everyone:
I found an online "book" about boron-doped diamond electrodes, wherein the author implies that, for purposes of electrochemistry, the graphitic (SP2) carbon content in the DLC film should be < 1.0%...lest conduction in the unwanted graphite "short circuit" the active diamond surface. If this is actually the case, then it seems that all the electrodeposition methods known to date are inadequate.

Here's an interesting paper to read.

jpsmith123 - 19-2-2009 at 20:46

I wonder what boron compounds would be the best candidates to try to dope it with?

Attachment: Facile Synthesis of Poly(hydridocarbyne) A Precursor to Diamond and Diamond-like Ceramics.pdf (176kB)
This file has been downloaded 1854 times


dann2 - 15-5-2009 at 16:35

Hello,

Came accross the following attachment. Might be worth a read.
Dann2

Attachment: Doped Diamond, A compact review.pdf (804kB)
This file has been downloaded 456 times


Hydragyrum - 15-5-2009 at 17:22

So, are electrodes of diamond-like carbon the same as glassy carbon electrodes?


My understanding of glassy carbon is that it is comprised of 100% sp2 C as far as can be detected, it is amorphous, but also conducts electricity like graphite. As it is supposed to be impervious to most things (or to everything?) then perhaps it is amorphous graphite with a surface coating of diamond.

In any case, has anybody here tried glassy carbon as an electrode material?

dann2 - 16-5-2009 at 07:06

Hello,
I have never heard of anyone trying it. It cannot be got AFAIK.
Do know any sources? Is it expensive?

Dann2

Hydragyrum - 16-5-2009 at 16:03

It can be bought here.

Some info about it is here and here. This paper (sorry, I have no access) seems to suggest that glassy carbon is composed of fullerene nanotube - well, that's consistent with the 100% sp2 claim made elsewhere.

In fact, a large list of further info can be found here and here.

Disclaimer: I have no first-hand knowledge of this stuff, but it sure looks interesting.

jpsmith123 - 19-5-2009 at 18:33

Hello Hydragyrum,

I have also never heard of anyone trying glassy carbon.

However there's one patent I know of, US #5131989 which mentions the use of glassy carbon as an anode in some kind of perchlorate producing cell. According to it:

"Materials which can be employed in the anode structures include platinum and platinum group metals, metal substrates coated with platinum or platinum group metals, platinum group metal coated substrates, glassy carbon, fluorinated carbons, lead dioxide and metal substrates coated with lead dioxide, noble metal oxides, and metal substrates coated with noble metal oxides. Suitable metal substrates include valve metals such as titanium and niobium among others. Especially useful as an anode is a platinum coated niobium expanded metal having, for example, 100-200 mils of platinum metal bonded to the niobium substrate".

So it might be worth testing if you can get some at a reasonable price.

Hydragyrum - 20-5-2009 at 03:04

Sorry, I have no direct experience... but what I have read suggests that this material is used by quite a few. If it's as impermeable as is suggested, price is kind of irrelevant as the electrode probably won't degrade much, if at all.

jpsmith123 - 20-5-2009 at 03:40

Well the primary question is: Will it make perchlorate efficiently or will it make oxygen? If it won't make perchlorate then it doesn't matter how much it erodes since it's useless.

Hydragyrum - 20-5-2009 at 04:40

Quote: Originally posted by jpsmith123  
Well the primary question is: Will it make perchlorate efficiently or will it make oxygen? If it won't make perchlorate then it doesn't matter how much it erodes since it's useless.

For that particular use (making perchlorate), it may be useless (I don't know which it would produce, perchlorate or oxygen); this does not make it useless in general.

Anyway, it is just another possibility to try.

jpsmith123 - 20-5-2009 at 04:55

Quote: Originally posted by Hydragyrum  
Quote: Originally posted by jpsmith123  
Well the primary question is: Will it make perchlorate efficiently or will it make oxygen? If it won't make perchlorate then it doesn't matter how much it erodes since it's useless.

For that particular use (making perchlorate), it may be useless (I don't know which it would produce, perchlorate or oxygen); this does not make it useless in general.


If you've been following the the relevant discussions in this forum (including this thread), you'll see that we're talking specifically about finding an alternative to Pt and PbO2 with regard to production of perchlorate.

Quote:

Anyway, it is just another possibility to try.


Well of course it is.

Hydragyrum - 20-5-2009 at 05:09

Well yes, it would be a useful thing to find something to favour perchlorate formation over O2 formation - that is undeniable. My point is that it looks interesting as an electrode material in any case... and it was the 'diamond' that got me into this thread initially, hence the carbon - though that's neither here nor there.

Perhaps if people wish to keep a thread glued to a single topic they might at least include that term in the title? Just a thought :D

jpsmith123 - 20-5-2009 at 06:32

Quote: Originally posted by Hydragyrum  
Well yes, it would be a useful thing to find something to favour perchlorate formation over O2 formation - that is undeniable.


As I said, that is what this thread is about.

Quote:

My point is that it looks interesting as an electrode material in any case... and it was the 'diamond' that got me into this thread initially, hence the carbon - though that's neither here nor there. Perhaps if people wish to keep a thread glued to a single topic they might at least include that term in the title? Just a thought :D


First of all, chump, if you apparently weren't so lazy, maybe you would've searched the forum before posting and found one of the other threads about "glassy carbon" like this one.

In any case, it's clear from the substance of my first post in this thread what the context is. Yet you blow in here off the internet and with only a few posts to your credit and apparently without doing any searching of the forum or reading any of the related threads you're going to lecture me on how I should have titled the discussion?

Hydragyrum - 21-5-2009 at 01:03

Well, that was not my intention at all - how old are you anyway?

jpsmith123 - 21-5-2009 at 08:10

Quote: Originally posted by Hydragyrum  
Well, that was not my intention at all


Then that's apparently a matter you should discuss not with me, but with your mental health care provider.

Quote:

- how old are you anyway?


Let's see, first, you want to use my diamond anode thread to discuss glassy carbon; then, you want to change the context from primarily that of perchlorate production to "general"; now, you're trying to completely derail the thread with your childish innuendo?

Well, in reply to your question, I'm old enough to ask you: Does your Mommy know you're at the computer again?