Superconductors And Applications

ABSTRACT

In the next few pages I will be talking about superconductors, I will be trying to inform the reader on every thing I know on superconductors, which is not much but hopefully I could talk the reader into trying to figure out a way to make things more energy efficient, but probably not since the only person reading this will be the professor or a teachers assistant how knows everything that I will be saying. However the reason I wanted to write this paper is because of what Dr. Dahiya said the first or second day of class, which was about superconductors and semiconductors, but it was the thing about superconductors that made me think. Once you have read the paper I hope that the point that I get across is what superconductors are and how they could help the world.

INTODUCTION

At the beginning of General Physics II (PH-230-01) at Southeast Missouri State, the class was introduced to the instructor, Dr. Dahiya. After all the basic stuff was said and done he said that he wanted to tell us about superconductors and semiconductors. Since this paper is about superconductors that is what I am going to talk about. Dr. Dahiya really made me think, and after class I have always thought about electricity and other things to lose energy to heat. Dr. Dahiya said that who ever could come up with a superconductor that is cost efficient would be so rich that that person's great-great-grandkids would be taken care of, that is how much superconductors could change the world. Now some people have made superconductors and there are superconductors out there, but none that would be cheap enough to use on power lines, car engines, and other things that make energy. Dr. Dahiya [1] said that out of the 100% of electricity sent to houses and businesses only about 50% of the electricity makes it there. It is lost do to heat because the atoms are not going in a straight line, the heat makes the atoms come in contact with each other and when those atoms collide with each other and they don't make it to there destination. However if we could keep the power lines cold enough then the atoms would stay in the straight line and out not be lost to heat, then the 100% of electricity would make it to the house or building. This is also the same for engines in cars, when the engines are running and producing energy it gives off heat and some of the energy is lost so the cars have to run harder and use more gas, but if the engines would be 100% efficient then they would not use as much gas which would in turn save more money.

The thing that makes it hard to figure out how to make superconductors is because of the temperature that has to be applied to the metals. The temperature has to be very cold to get the resistivity to zero; I remember Dr. Dahiya said that you could get the power lines to be superconductors by running liquid nitrogen across them but liquid nitrogen is very expensive to use. When I was looking for information about superconductors to see if there were any that the temperature did not have to be so cold and I found a website that stated this, "High-temperature superconductivity in the copper oxides, first discovered twenty years ago, has led researchers on a wide-ranging quest to understand and use this new state of matter. From the start, these materials have been viewed as `exotic' superconductors, for which the term exotic can take on many meanings. The breadth of work that has taken place reflects the fact that they have turned out to be exotic in almost every way imaginable. They exhibit new states of matter (d-wave superconductivity, charge stripes), dramatic manifestations of fluctuating superconductivity, plus a key inspiration and testing ground for new experimental and theoretical techniques."[2] This really just seemed to say no there is not and I will be a long time till we even find something that can make metals cold enough to be come superconducting, which bring me to making superconductor cold.

Then in the physics book we use in class by Douglas C. Giancoli [3] stated that, "At very low temperatures, near absolute zero, the resistivity of certain metals and certain compounds or alloys becomes zero as measured by the highest-precision techniques. Materials in such a state are said to be superconducting." After looking for information about superconductors I found that a lot of the research that others have done was found in recent years, I think that the reason for this is because we now have created other equipment that can bring certain elements or compounds cold enough so that the compound or elements does not have any resistance, which was first observed by H. K. Onnes in 1911. Onnes was the first in recorded history to make mercury non resistant. He did this by cooling the element with liquefied helium to a temperature below 4.2 Kelvin (K) which he then applied to mercury to bring the temperature to 4.2 (K) [4] [5], which is , and for those that don't know how cold that is it would be which is very cold. This had to have been unbelievably hard for Onnes, he new how to test resistivity, but not how to cool something to . Like I mentioned earlier when I was talking about Dr. Dahiya telling the class about power lines and engines, it was said again in Giancoli's book, where he said, "Electric motors, generators, and transformers using superconductors are also being worked on, and will be much smaller and lighter than conventional ones. Prototype motors under development are half the size and weight of non-superconducting motors [6]." This really just backs up what I mentioned earlier about how much this would help the world; smaller engines would use less gas which would in turn use less exhaust which would cut down on ozone depletion.

THEORY

First we need to start out by saying that is the transition temperature and is resistivity. It was said that (measurement of resistivity) for a superconductor is smaller than . In a book Superconductivity: Experimenting in a New Technology [7] it said that superconductivity is really just any metal that when it is given a certain temperature and magnetic field strength then that metal will be smaller than a fixed amount given to that metal. To put this in to an equation the book I just mentioned with was written by Dave Prochnow said,

" ."

Where is the critical field strength at a certain temperature (T), is the maximum critical field strength at absolute zero, T like a said is temperature, and then is the critical temperature.

Like anything else superconductors have properties that they follow, with out these properties then a superconductor would not be a superconductor, just like with out oxygen there would be not water.