

Metals in your smartphone have no substitutes - nzp
http://theconversation.com/metals-in-your-smartphone-have-no-substitutes-21142

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downer91
It'd be nice if the article went into detail about the particulars of what
might be so indispensible about certain elements.

Why are rhenium, rhodium, lanthanum, europium, dysprosium, thulium, ytterbium,
yttrium, strontium, thallium, magnesium and manganese so irreplacable?

Is it catalytic reactivity, phase transition tempratures, crystal formation
tendencies, quirks in solid state semiconductor chemistry?

Is the article light on details so that people don't develop cute ideas about
cornering markets? What's the deal here?

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nzp
Yeah, I was kinda hoping people would touch on those questions here. I haven't
managed to read the actual paper, but it's just 5 pages longs so I doubt it
speaks much about these questions. But a piece discussing these particulars
would be awesome.

~~~
downer91
Alright, so here are some of the most common applications, although I'm not
sure about the chemistry behind them...

Rhenium: High performance super alloys, particularly when mixed with tungsten,
mostly useful in turbine jet engines and heat exchangers. Also used as a
catalyst in petroleum cracking when distilling crude oil. Isotopes are used as
radiation sources.

Rhodium: A non-reactive metal with characteristic shine, mostly used as beads
in automotive catalytic converters. Also used for jewelry and decorative
purposes. Also as an good electrical conductor included in alloys for niche
wiring applications and as a fiberglass additive.

Lanthanum: Commonly used as gas lamp mantles, but many other uses include
acting as a cathode ray source, neutron and gamma ray detector, glass
additive, alloy additive, all rare earths in the lanthanide series are useful
as catalysts for petroleum cracking when distilling crude oil, and finally
potential use in hydrogen fuel cells to sequester hydrogen.

Europium: Flourescent lamps, red phosphors in cathode ray tubes, anti-
counterfeiting agent due to unique flourescent properties.

Dysprosium: Mostly magnetic applications. Can be used as a neodymium
substitute with unique magnetic properties for niche applications, such as
improving conductivity is solenoids for high performance electric motors, and
in magnetic media such as hard disk platters.

Thulium: Very rare and expensive, but useful as a safe low-intensity x-ray
source, also used in solid state lasers, and due to rarity as an anti-
counterfeiting substance with unique flourescant properties.

Ytterbium: Miniscule vitrified sampled are bombarded by lasers as the time
keeping component in high quality atomic clocks. Radioactive isotopes can be
bombarded with neutrons to produce gamma rays.

Yttrium: Red phosphors in CRT monitors, emits white light from LEDs,
semicondoctor doping agent, and lots more.

Strontium: Mostly mixed into glass to shield against x-ray emissions from
cathode ray tubes.

Thallium: Mixed with glass to provide special properties, regarding hardness,
optical effects and infrared effects. Also used as semiconductor doping agent.

Magnesium: Mostly used as a component of alloys, mixed with other metals to
fabricate durable lightweight parts. Comparable to aluminum.

Manganese: An important metallurgical component in steel production, both when
refining raw iron ore, and as a component of high quality steel alloys.

I guess it's a pretty wide mix, since many of the elements come from all
across the board, on the periodic table. Recurring themes are alloys, glass
additives, semiconductors, and chemical catalysts.

~~~
lewispollard
How come Rhenium is in the list of metals without substitutes, but also given
as an example of a metal that was successfully substituted by General
Electric? Is it just that it serves a different purpose in smartphones that
nothing else can be adequately used for?

~~~
downer91
Wikipedia's article seems to point to the idea that recently, super alloy
applications are placing high demand on a supply chain that was not prepared
for such a change in market trends.

I think rhenium diboride seems to be a useful substitute for tungsten carbide
in places where tungsten carbide is useful for its hardness. Apparently
rhenium is used heavily in the production of tungsten alloys, so there's an
association, in that industrial pipelines involving tungsten tend to have a
lot of rhenium on hand too.

Meanwhile the super alloys which involve high use of rhenium are nickel-
rhenium alloys. Apparently GE has produced a series of super alloys named Rene
alloys, and the compositions vary among each memeber of the series, some don't
involve rhenium. Given that they seem to be proprietary products with military
applications (mostly high temperature rocket engine nozzles) details are
somewhat scarce.

Maybe the demand directly relates to how many rockets are being launched, and
how many fighter jets are serviced for replacement parts or lost in crashes?

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wycx
What is Rh used for that is so specialised that it cannot be substituted by
another PGE?

It's a bit of a stretch to suggest that Mg and Mn are at all critical since
they are major rock-forming elements without geographically restricted supply.

Similarly, Sr is sufficiently abundant that we need not worry about running
out, only the cost of extraction/recycling old CRTs.

