Lovely!
I’ve just realised that erbium is the most crucial element for the internet
of all the elements on the periodic table, and so I want to take you
across to materials engineering where we can see a demonstration which
will explain to you why it’s so important, and why without erbium many
of you couldn’t be watching this video.
Erbium is another lanthanide metal. It’s soft, silvery, quite malleable,
very reactive towards oxygen and water and, I suppose, for us right now
it’s quite significant, because it was originally discovered from a mineral
which was found in this quarry. So we’re in a quarry in Sweden near
Stockholm, called Ytterby Mine and some black minerals that were found
in this quarry actually were the birthplace for four new chemical
elements and erbium was one of them.
Erbium is a photographic filter and it is actually a nuclear poison. What
that means is that it will kill dead any nuclear fission process so it’s
obviously got some applications there. It’s an interesting element when
you make compounds of it and dissolve it in solution it often goes pink.
Now this is some erbium trichloride. You’ll notice it’s very slightly pink. I
think this is one of the ones that, because of its pink colourations, get’s
used in jewellery and things like sunglasses and things like that, if
memory serves.
More recently erbium is used as an amplifier of light as it’s transmitted
down optical fibres.
So, the reason we are here, and why I’m all dressed up, these are the
fibres that transmit the signals for the internet. Now the reason they use
fibres is because copper cables which you would normally use for
electrical signals cannot carry nearly as much information, as many
YouTube viewings at once, as one of these fibres. And the fibre is very
strong, neither Brady nor I have managed to break it, and the problem
is that even with this fibre, with the light beam going down it, eventually
the light gets weaker and weaker and you lose the signal. So every
50km, every 30 miles or so, down the fibre when it’s under the sea you
have to amplify the signal to get it back up again so that our YouTube
video can reach the other side of the Atlantic or to India or wherever.
And so the way you’ve got to do it you’ve got to somehow amplify the
light, make it more intense, and you can do this with erbium because if
you put erbium into the glass then if you shine a light onto the erbium
atoms they get excited and then as the light comes in from the signal it
interacts with the erbium atom and the erbium atom loses its energy and
gives out more light. So essentially the light comes in and comes out
twice as intense. It then keeps going another 30 miles and you repeat it.
Here we’ve got the infrared laser, I used to work with lasers, but I’ve
rather given up now. So it’s quite nostalgic. Is it switched on? And if you
put this in the laser beam you can see there’s a special screen here,
which will actually take an infrared laser beam which you can’t see and
make it into visible light so you can see it. We’ve got infrared light going
into a piece of glass with erbium in it. Now, what is happening here is the
physics here is slightly different from what happens in the amplifier, but
is really quite fun because the light beam that you can’t see is suddenly
being changed into visible light, to green light, which you can.
Yes it’s very important, I had heard about it in lectures but when we
videoed our first video about erbium I had completely forgotten about
this, although without it nobody would have seen any of our videos.
Welders, people that join pieces of metal together using either large
electric fields or extreme temperatures have special masks to protect
their eyes from the very bright light which is given out in the welding
process. Welding goggles typically can include erbium salts because they
are intense and they absorb a massive amount of the light so the eyes of
the welder are not damaged at all.
So, under the sea you have these fibres with copper wires going next to
it carrying the currents for the diodes that excite the amplifiers all the
way along and, apparently, the current going down these wires is quite
attractive to sharks and so in shallow water sharks come along and see
the cable and it seems attractive and they start chewing it and, although
Brady and I can’t break the fibres, a shark in full spate can easily cut
through it and so there have been quite alot of problems with the optic
fibres in shallow water being chewed to bits by sharks.