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Rosco Bodine
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abstract concerning van Leent article
Here is an abstract summarizing the more extensive
article by van Leent concerning the anomalous "solubility"
of what is evidently a doped tin oxide dispersion , in
the form of a hydrated metastannic oxide sol .
I suspect that the van Leent material could accurately be called a clathrate , and similarly there are many other of the
doped tin oxide materials which are probably also
coordination compounds .
Edit: errata - ( coordination compounds ) should read
*inclusion compounds*
[Edited on 10-2-2008 by Rosco Bodine]
Attachment: Abstract for van Leent article.pdf (103kB)
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tentacles
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So, Rosco, would metastannic acid (H2SnO3) be appropriate for a DTO precursor? The metastannic acid ppt that I had previously formed (and foolishly
disposed of) was certainly water soluble, as long as there was not too much HNO3 in solution. It would seem like the decomposition would leave SnO2
(once the water was driven off)
[Edited on 14-1-2008 by tentacles]
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Rosco Bodine
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There seems to be no reason why the anomalously soluble
binary of metastannic acid with iron nitrate or perhaps chromium nitrate would not make an excellent
DTO precursor , since the metastannic acid is a higher intermediate in the pyrolytic decomposition sequence of other materials making their way to a
baked DTO coating .
Iron is an already identified dopant of value for the DTO coatings useful as anodes . The proportions might have to be adjusted and the pH adjusted
in mixture with other components so that everything stays soluble , but yeah I think it certainly has promise as a DTO precursor particularly since it
forms a highly loaded "solution" ,
and the SnO2 is "already there" as the oxidized Sn not
requiring aerobic baking to develop , but only being baked to dehydration and sintering .
This contrasts with a chlorides precursor which has to hydrolyze and lose its chlorine , absorb oxygen and dehydrate to end up being SnO2 , which
requires longer baking and higher temperature and would never really be so complete for the material buried deep in the layer .
So .....the binary composition with metastannic acid is a higher developed precursor , for the DTO .
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Rosco Bodine
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dyer's tin nitrate described (more or less)
This bit of obscure information was gotten from an english trade journal circa 1877 , The Textile Colourist , and is the
single description which I have been able to find concerning
a preparation of a reported *Stannic* nitrate , directly from
tin metal using nitric acid .
By this method the product appears to actually be a mixture
70% stannic nitrate with 30% stannous nitrate by analysis
methods of that era . The nitric acid concentration used is
reportedly d 1.17 , 28.5% HNO3 , with the dissolving of the tin 1 part in dilute acid 8 parts by weight , the process done
slowly so the exotherm is kept small , reaction temperature
kept below 100F according to one source and 60F according to another . The resulting soluble nitrates of tin is a solution of density 1.3 having 14%
tin content as the metal .
From this source and from others there is indication that the presence of some HCl enhances the storage stability , also
the presence of NH4NO3 as a minor proportion . From other sources as a more general consideration with regards to the delaying of precipitation by
hydrolysis of soluble tin compounds , a small percentage of iron as an impurity is
stabilizing . Less explicitly reported are indications that
also tartaric and acetic acids may be stabilizing against precipitation , all of these materials seeming to act as dispersants which hinder the
nucleation and growth of colloidal particles , thereby hindering precipitation from hydrolysis .
Obviously this mixture of stannic and stannous 70/30 is
a mixed valency composition , and what would be the properties similarity with a single valency stannic nitrate
derived from a nitric acid neutralization of precipitated alpha stannic oyhydroxide is unknown . But one thing that is shown by this old reference
is that the nitrates of tin in
at least the simplest case of reacting dilute nitric acid with tin metal , can be made and has sufficient stability if kept cool in storage , to be
useful at least for some weeks time of keeping . And this may perhaps also be true for the 100%
stannic nitrate composition , particularly if some stabilizing benefit is accomplished by means of those things identified to hinder precipitation in
storage being added as stabilizers .
Attachment: Dyers Stannic Nitrate.pdf (449kB)
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woelen
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It is funny to read such an old article from 1800 or so. Especially all the different types of nitric acid are nice to read. Apparently, at that time,
one could not make pure HNO3 and acid of different purities is regarded another type of acid.
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Rosco Bodine
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Yeah I noticed that the nitric acid which was regarded
as being the "good stuff" was Dutch manufacture ,
while the English made acid was simply adequate 
and I'm sure you got a good laugh from that
A proper chemist should only use politically correct HNO3 
[Edited on 23-2-2008 by Rosco Bodine]
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microcosmicus
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As for different concentrations being regarded as different chemicals, remember
that Lavoisier thought that acetic acid and glacial acid were different chemicals.
This and similar confusions in elementary chemistry such as HO rather than H2O
only got straightened out for good by the middle of the nineteenth century.
However, I do not think that this is exactly the reason for the different names in
the article. Remember that this is written for people who dye cloth, not for chemists.
Therefore the names given there would be the names which suppliers used for
the acids they sold at the time. Even though chemists certainly understood what
nitric acid was by 1877, suppliers probably still sold varying dilutions and grades of
purity under different names, so naturally a recipe for dyeing cloth would use these
names to make it easier for the intended audience to use the recipe. While the
chemists understood what was going on and adjusted their terminology accordingly,
it took a lot longer for people selling industrial chemicals to catch up and start
using names like "10% nitric acid" instead of "double aqua fortis".
To some extent, I encounter a similar situation when I go to the pottery shop
and have to translate chemical names into their terminology in order to be
understood. They even still use some old alchemists' terms like "crocus
martis" and "pearl ash" as well as trade names instead of chemical names.
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Rosco Bodine
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On the first page of this thread a patent US3243385 was posted which described production of stannous nitrate .
It appears that the clear solution described in example 2 of that patent is more likely a solution predominately the +IV
stannic nitrate , and the patents identification is in error .
The figures for quantities and strengths of HNO3 have been compared with the old Dyers Nitrate of Tin , and the preparations are very close to the
same .
Yes that's four smileys for the +IV valency Tin Nitrate .
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Rosco Bodine
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more ancient art involving tin nitrate
Here is some more interesting observations
recorded in the older literature ,
concerning some anomalously soluble ,
reasonably stable mixtures of tin nitrate with
tin chloride in stable complex mixtures .
It is my belief that Ordways colored mixed valency
compounds of tin , in varying proportions of both
nitrate and chloride is very likely due to the formation
of Pytlewski polymers later described in US3890429
and US3676186 , which are also reported colored materials
yet derived from precursors which are colorless . Also
is probably present some double salt complex with
ammonium chloride and possibly also ammonium nitrate .
These products formed in the reaction system likely account
for the anomalous solubility and stability for the mixture
under lower conditions of acidity than would be allowable
for the individual components to remain in solution .
The anomalously soluble complex mixtures are very possibly sols ,
and not simple solutions . This would also agree with
the hypothesized Pytlewski polymer formation , given that the materials
can be dried (without heating) to a residue and the residue
can be redispersed in plain water to reconstitute the original sol .
At any rate this seems to be a valid method for getting
a highly concentrated , high tin content sol or solution , without
an excessively acidic condition for maintaining the solution or dispersion ,
which may be useful as a precursor for baked SnO2 coatings
that should result from the thermal decomposition and
dehydration and sintering of these compositions .
[Edited on 1-3-2008 by Rosco Bodine]
Attachment: Tin Nitrate stable complex mixtures (1857 Chemical Gazette article).pdf (908kB)
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