Pages

July 17, 2008

195K superconductor at dry ice temperatures


The formula for the 195K superconductor is (Sn1.0Pb0.5In0.5)Ba4Tm6Cu8O22+. Its 1256/1212 structure is shown.

A new method of production was developed. This new method of synthesis, layers of 12x(x+1) and 1212 precursors are alternated in a "layer cake" arrangement before sintering. Each layer was initially pressed at 200 psi. Then, once all the layers were set, the entire pellet was pressed at 70,000 psi and sintered in the UPRIGHT position. When sintered in the "sideways" position, very little of the desired phase forms. This suggests gravity facilitates migration of the heavy thulium atoms. This technique results in the desired phase forming along interference boundaries.

Ten times more 185K superconducting material was made and detectable amounts of 195K material.

The 195K material is being patented. But the new method of synthesis is being released into the public domain without patent protection. It may be used freely without limitations. When combined with the Tao Electrostatic Separation Technique, this method should be able to produce a near homogenous 195K bulk superconductor
.

NOTE: this was a highly systematic process to modify the makeup of the material to find a higher criticial temperature structure.

The number of families of superconducting material is providing more points of data for creating unified theories for all superconductors. Successful unified theories would be able to guide the experimentalists even better on optimal doping strategies and changes to the structures to tune the various properties of the superconductors. This could allow rapid progress to the creation of room temperature superconductors and material for moving higher energy density and optimizing many other useful properties.

There is also a low energy model and electron pockets hole model



This year has seen excellent experimental progress being made to room temperature (300K) superconductors as well as theoretical progress. There has also been the whole new class of higher temperature iron based superconductors.

Getting up to dry ice temperatures will lower the cost of using the superconductors because the cooling problems will be greatly simplified. It gets us closer to the goals of room temperature superconductors and some of the applications could be possible with dry ice. Even the superconductors that need a lot more cooling are being used for more efficient engines and generators that are three times smaller than conventional. There has also been a commercial pilot of superconducting cable for electric utility distribution. Superconductors can also make better magnets for nuclear fusion reactors.

It appears that dry ice cooling temperatures are two to seven times cheaper than liquid nitrogen temperatures.

WHAT WOULD COMMERCIALLY USABLE ROOM TEMPERATURE SUPERCONDUCTORS MEAN ?
BBC News talked about that anticipated but delayed vision from the hoped for results from the 1987 "warmer" superconducting breakthroughs.

Levitating high-speed trains, super-efficient power generators and ultra-powerful supercomputers would become commonplace thanks to a new breed of materials known as high temperature superconductors (HTSC).


Those difficult to manipulate superconductors have been on track to make smaller and more efficient motors with commercial impact in 2010 South Korea was making significant advances with 1300hp superconducting generators.

They were also being tested in 36.5 MW motors for navy ships.

Electric car motors would shrink to be one third the size for the same power by using superconducting wire. Similar to the previously mentioned improvement for the large superconducting motors of navy ships. It is more difficult to make a cost efficient superconducting small motor.

If room temperature superconductors were cheap to make they could replace batteries and also the need for a car engine by storing the power to run the car. Currently this is cost prohibitive. Wikipedia has an article on superconducting magnetic energy storage



Here was a more recent list of predictions of what "warm" superconductors that we had before the most recent two announcements could provide. 100Tbps routers, faster communications, faster computers, better sensors and more. Room temperature versions would make all of these things cheaper, more widespread and more powerful.

If the new room temperature superconductors have or can be made to have a very high current density relative to their weight, then there is the possibility of a ground launched magnetic sail or high performance magnetic sails for space propulsion.

31 page pdf of the 1999 Zubrin study for Nasa on magnetic sails






Getting up to 100 billion to 1 trillion or more amperes per cubic meter is the current density for high performing magnetic sails.

D.G. Andrews and R.M. Zubrin, "Magnetic Sails and Interstellar Travel." Journal of the British Interplanetary Society, 1990. The first paper published, concerned primarily with the cost savings to other propulsion systems from the use of the magsail as an interstellar brake.

R.M. Zubrin and D.G. Andrews, "Magnetic Sails and Interplanetary Travel." Journal of Spacecraft and Rockets, April 1991. The technical description and very thorough analysis of the magsail for interplanetary travel. Excellent.

R.M. Zubrin, "The Magnetic Sail." Analog Science Fiction & Fact, May 1992. A version of the above paper edited for a non-technical audience. Useful for general concepts, inadequate for a full understanding.



FURTHER READING
Electrostatic Separation Technique for Superconductors is described here. This technique will work to separate superconductors from metallic as well as non-metallic materials.

In the electrostatic separation technique, a vertical capacitor cell with dimensions 18mm X 15mm X 15mm was fashioned from a U-shaped teflon spacer. 2 brass plates were attached to the open sides of the spacer to create a cavity and provide electrodes for the capacitor. The cavity was filled with liquid nitrogen and particles of roughly 25-38um size were placed in the pool. High voltage (1100 dcv/mm) was applied to the two metal electrodes for at least two minutes. The electric field was then reduced (to 333 dcv/mm) for one minute. After collecting the respective particles, they were found to be essentially pure BSCCO and pure Sb.


0 comments: