- 4046 - SUPERCONDUCTIVITY - when electricity is free? Will superconductivity happen at room temperatures? Superconductivity could bring us near free electricity, levitated train travel, MRIs in every doctors office and who knows what else. The challenge is getting superconductivity to work at high enough temperatures that it can be commercially produced.
--------------- 4046 - SUPERCONDUCTIVITY - when electricity is free
-
We are making progress. Superconductivity
is occurring at ever higher temperatures.
When we know why, a breakthrough will be imminent ,and, that physicists
with be eminent.
-
- Superconductivity is a property of metals
to carry electricity with zero resistance. No loss of power. No losses due to heat. It is amazing. The only problem is it occurs in materials
frozen to near Absolute Zero, - 273 Centigrade.
-
- A loop of this material at 4 Kelvin would
carry an electric current for ever without adding any additional energy to keep
it going. Several loops of this material
could create an electromagnet that would not draw any power once it was
started.
-
- If we could get superconductivity to work
at room temperatures we could have transmission lines that would send
electricity across the country with zero power loss. We could have trains on
magnetic railroad tracks that would levitate the entire train and send it along
with little to no power to keep it running.
-
- Magnetic Resonance Imaging could be
available in every doctors office because MRIs could be cheap and readily
available. Airport screening also comes
to mind. So, what is stopping
superconductors from going commercial?
-
- They only work at very low temperatures,
close to Absolute Zero. It takes liquid
helium to cool material down to these temperatures. Liquid helium is very expensive to produce.
-
- Superconductivity was first discovered in
Mercury in 1911. At 4 degrees Kelvin
electric current would flow in the frozen metal with no resistance. Once current was started it is still flowing
today. But, it took liquid helium
coolant to get to those temperatures.
-
- From that day on the search has been on to
find materials that are resistance - free to electron flow at increasingly
higher temperatures.
-
- In 1954 Niobium - Tin was found to be
superconductive at 18 Kelvin.
-
- Nioblum is an element with 41 protons and
41 electrons. Abbreviated Nb in the
Periodic Table and Nb(41) to designate the atomic number which is the number of
protons. Tin is Sn (50). Tin has 50 protons in the atomic
nucleus. The 50 electrons are in shells
of 2 + 8 + 18 + 18 + 2 + 2 = 50
-
- In 1986
a copper oxide was found superconductive at 35 Kelvin. LaBaCuO is the copper oxide. It is a compond of Lanthanum (57), and Barium (56), and Cu is
Copper (29) and Oxygen (8)
-
- In 2008 LaOFeAs was the first iron-based
superconductor at 26 Kelvin.
-
- Fe = Iron(26) As = Arsenic (33). Iron was not expected to be a good
superconductor material because of its rich magnetic properties. “Cooper Pairs” of electrons are what creates
super conduction and a strong magnetic field will break down Cooper Pairs. So, iron was not used in the research for a
long time. This material is a surprise
and shows that we do not understand superconductivity well enough.
-
- In 2001 Magnesium Diboride was
superconductive at 39 Kelvin.
-
- Magnesium(12)
shells are 2+8+2 = 12 was discovered in 1808. When combined with water is forms milk of
magnesia. It is lightweight (12) and is
used in building airplanes. It burns
brightly in fireworks. It is essential
fertilizer for most plants. Diboride, I do not know what that is.
-
- In 2008 SmFeAsO was superconductive at 55
Kelvin. Sm =
Samarium (62).
-
- In 1987 Yttrium Barium Copper Oxide was
superconductive at 92 Kelvin.
-
- Yttrium is Y(39). Barium is Ba(56). 92 Kelvin was a temperature above the boiling
point of liquid Nitrogen and liquid Nitrogen was a lot cheaper coolant to use
than liquid Helium.
-
- In 1995 Thallium doped Mercury cuprate went
superconductive at 138 Kelvin. Thallium
is Ti(81) and Mercury is Hg(80)
-
- In 2010 everyone is still trying to produce
the record high temperature superconductor material. The closer we can get to room temperature the
cheaper and more successful a commercial application becomes.
-
- How do these “high” temperature
superconductors work? What is the
physics that is going on?
-
- We are still trying to figure this
out. There seem to be two classes of
superconductivity. One is iron-based
discovered in 2008 at 55 Kelvin , and,
the other is copper-oxide based discovered in 1986 found to work up to 138
Kelvin. These copper-oxide materials are
called “ cuprates”. The problem with
them is that although they operate at the highest temperatures cuprates are
brittle and very hard to form into wires.
-
- The physics theory we are working with is
that superconductivity occurs because under certain conditions electrons can
pair up in what is called “Cooper Pairs“.
The pairing prevents electrons from bouncing off atoms in the lattice
structure and loosing energy. Somehow a
negatively charged electron passing through a lattice structure of positively
charged ions pulls nearby ions close creating a region of positive charge.
-
- The positive region attracts another
electron to come through the lattice and pair with the first electron. At high temperatures, above 30 Kelvin, the
heat energy, or vibration of atoms, is thought to break Cooper pairs
apart. Superconductivity would therefore stop above 30 Kelvin temperatures.
-
- When it was discovered that the cuprates of
Lanthanum, Copper Oxygen, Barium, a brittle ceramic material, worked at 35
Kelvin some new theories about how superconductivity was working had to be
found. La(57) Cu(29) O(8) Ba(56).
-
- The process of doping these compounds
seemed to make a difference. By
replacing some of the atoms swapping out other atoms changed the number of
electrons making superconductivity occur more easily.
-
- Iron-arsenic compounds can come in two
types, paramagnetic and anti-ferromagnetic.
When anti-ferromagnetic the material’s magnetic fields of individual
atoms line up in alternating directions.
Anti-ferromagnetic material combined with doping seemed to raise the
temperatures where superconductivity could occur.
-
- A lecture at SSU on 11-15-10: Dr. Pei-Chun Ho, a scientist at
Fresno State University gave a lecture on her experimentation at Fresno
with the superconductivity:
-
------------------ Pr Os4 Sb12
-
-------------- Pr =
Praseodymium (59) has 59 protons and an atomic weight of 140.91
-
----------------- Os
= Osmium (76) with 76 protons and
atomic weight of 190.
-
- Os 4 is an isotope of Osmium with the
nucleus also having 4 neutrons. Osmium
has electrons in the shells of 2 + 8 + 18 + 32 + 8 + 6 +2 = 76.
The metal was discovered in 1803 named of the Greek word meaning
smell. It combines with oxygen to
produce a toxic odor. It is one of the
hardest metals, along with Iridium. It
is the least compressible element, along with Carbon. Its extreme hardness is used in pens,
photograph needles, instrument pivot points, electrical contacts.
-
---------------- Sb
= Antimony (51) with 51 protons
and an atomic weight of 121.75.
-
- Antimony is a brittle, hard metal used in
ceramics its electons are in shells : 2 + 8 + 18 + 18 + 2 + 3 = 51. Sb12 is an isotope with 12 neutrons in the
nucleus.
-
------------ Another compound being studied is BaFe2As2P
-
--------------- Ba =
Barium(56) weight 137.34
-
--------------- Fe2
= Iron (26) weight 55.85, plus 2
neutrons
-
--------------- As2
= Arsenic (33) weight 74.9, plus
2 neutrons
-
--------------- P
= Phosphorus (15) weight 30.97
-
- This material exhibits both
anti-ferromagnetic and paramagnetic properties depending on degrees of
doping. It is superconductive at 45
Kelvin.
-
- You can imagine how complex these compounds
are to work with. The crystalline
structures are geometrically challenging to grow and to understand. Doping alters the lattice structures. Atoms come together in complex ways. Electrons navigate in the shells and somehow
they find a combination where navigation is resistant - free. -
Electricity
flows freely, no loss of power, no thermal energy generated.
-
- There is a Nobel Prize for sure in
someone’s future if they can discover the combination of materials that work at
very high temperatures, above 273 Kelvin.
And, to the physicists that can explain how this happens?
-
- Cooper Pairs are being challenged as the
only idea. There is really basic
fundamental research at the Quantum Mechanical level involved here. That is why superconductivity is weird. If you are not confused you really do not
understand the problem.
-
-
June 9, 2023 SUPERCONDUCTIVITY -
electricity?
1224 4046
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Monday, June 12, 2023
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