Re: barium titanate doorknob caps/beryllium

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-uswest-dot-net>" <jimlux-at-earthlink-dot-net>

The various titanates (Barium, Strontium, etc) are ferroelectric have very
very high dielectric constants (epsilon) (tens, hundreds, or even thousands,
compared to oil, plastic, etc. at a whopping 2 or 3), so you can get a lot
of capacitance in a small area.  Ordinary red clay (or white, for that
matter) is probably mostly some silicate, and probably has a dielectric
constant similar to dirt, silica, etc., that is, around 3).

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, April 22, 2001 1:16 PM
Subject: Re: barium titanate doorknob caps/beryllium


> Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<uncadoc-at-juno-dot-com>
>
> Hi all, I am sticking to the good old red clay from my backyard for
> capacitor fusion experments. You folks got me scared now with this
> Barium/Beryllium stuff.  But what differentiates good old red clay from
> the barium stuff?  Is it written in 'stone' that a ceramic cap must be of
> barium composition? Al.
>
> On Sun, 15 Apr 2001 16:31:04 -0600 "Tesla list" <tesla-at-pupman-dot-com>
> writes:
> > Original poster: "Dr. Duncan Cadd by way of Terry Fritz
> > <twftesla-at-uswest-dot-net>" <dunckx-at-freeuk-dot-com>
> >
> > Hi Ed, Jeff, All!
> >
> > Happy Easter!
> >
> > >> Keep in mind though that Barium anything (salts, oxides, nitrates
> > etc) are
> > >> very toxic.
> > >> --jeff
> > >
> > > I think you men Beryllium rather than Barium.  As anyone who has
> > ever
> > >had a GI X-Ray exam, it is quite common to use Barium (something
> > >soluble, don't know which salt) taken internally to define the
> > >intestines.  Don't believe that would be done if it were toxic at
> > all.
> > >Ed
> >
> >
> > Well actually Jeff is right and Ed is right.  Soluble barium salts
> > are
> > toxic.  The stuff used in barium meals is a suspension of finely
> > powdered barium sulphate (or possibly sulfate ;-) which is highly
> > insoluble - just a quarter of a milligram dissolves per hundred ml
> > of
> > water at 25C (it occurs naturally as barytes or "heavy spar") and
> > therefore non-toxic because the barium is locked up by the sulphate
> > ion and not accessible to the body.  Barium, when accessible to the
> > body's chemistry, is toxic.  However . . .
> >
> > Beryllium on the other hand (as found in beryllium copper alloys,
> > high
> > power transistors etc as salts used for a heatsinking material
> > within
> > the case) is in a different league.  It is _very_very_ toxic and is
> > absorbed and accumulates easily in the body, so this may be an
> > opportune moment to get on my chemistry soapbox and sound a general
> > note of warning on beryllium.
> >
> > You really should avoid machining, filing, heat-treating/welding etc
> > beryllium alloys under home workshop conditions as the dust/vapour
> > will do you a lot of serious no good. The pros can summon the aid of
> > all manner of air monitoring, regular blood testing, containment and
> > filtration mechanisms outside the range of an enthusiast's workshop.
> > Never, never cut open a power transistor case.  Not all of them
> > contain beryllium salts, but the risk isn't worth it.  If you have
> > done any of these things, consider a blood screening seriously.
> >
> > One of my ex-professional colleagues did a fair percentage of all
> > the
> > world's known organometallic chemistry of beryllium.  His research
> > was
> > officially stopped because of the toxicity problems - and this was
> > in
> > the 1970s so you can guess how it must have been to attract
> > attention
> > from officialdom back then.  (Back then, we were still boiling
> > benzene
> > on the open bench.)  If you're into literature searching, look for
> > papers by Prof. Coates of Durham uni, which might also bear the name
> > Tom Caygill (my colleague, who was Prof. Coates' technician and who
> > actually did most of the benchwork.)
> >
> > Dunckx
> >
> >
> >
>
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