23 K 1973 Nb₃Ge

35 K 1986 LaBaCuO₄

92 K 1986 YBa₂Cu₃O₇

110 K 1987 NiCaSrCu₂O₉

125 K 1988 TISrBaCuO

133 K (up to 160 K 1993 HgBa₂Ca₂Cu₃O₈

under pressure)

There were many instruments used in our synthesis of a high temperature superconductor. Primarily a furnace was used because of the 950° C needed to heat the sample. We utilize the solid-state reaction method of the synthesis in which the starting materials were weighed, mixed thoroughly and ground with a mortar and pestle until our sample was a uniform gray color. The sample was then heated in an Al₂O₃ boat. The sample was ground and reheated several times. Finally, the sample was ground pressed into a pellet for testing.

We prepared approximately 30 grams of YBCO in our experiment. We had to determine the exact amount of each compound to use. The solid phase reaction is based on the following equation:

0.5Y₂O₃ + 2BaCO₃ + 3CuO à YBa₂Cu₃O_6+x + 2CO₂

C,O are remove as gasses. They are not accounted for in balancing the equation. To produce 30 grams of YBCO we calculated the required amounts of starting materials (see left side of above equation)

2(137.33) = 274.66

3(63.546) = 190.638

7(15.9994) = 111.9958

666.1997 grams/mole

30g of YBCO = 0.0450315 moles of YBCO

666.1997 g/m

2(88.9059) = 177.8118

0.0450315 moles of * 225.81 g/m = 5.084 grams

2

2(0.0450315) * 197.3392 = 17.77296 grams

3(0.045.315) * 79.5454 = 10.813799 grams

During our project we used an x-ray diffractor and a raman spectrum to determine if our sample was pure or not. The x-ray diffractor showed our sample was very similar to a pure one (see chart of d-space and intensity measurements). The Raman Spectrum was not inconclusive. However, the Meissiner was positive.

We knew our sample was pure when we tested it for the Meissner effect. The Meissner Effect is the phnomenon where a superconductor expels all magnetic fields. A light powerful magnet will then float above the superconductor if the temperature of the superconductor is below its Critical temperature. Our sample was chilled using liquid nitrogen and as soon as it reached its critical temperature the magnet began to float above the superconductor pellet. This proved definitively that we had synthesized YBCO.

Application Current Emerging

Medical

Magnetic resonance image x

Biotechnical engineering x

SQUIDs x

Transistors x

Josephson Junction devices x

Circuitry connections x

Particle accelerators x

Sensors x

Separation x

Magnets x

Sensors and transducers x

Magnetic shielding x

Motors x

Generators x

Energy Storage x

Transmission x

Fusion x

Transformers and Inductors x

Magnetically levitated vehicles x

Marine propulsion x

Bc(T) = Bc(0k) [ 1 – (T/Tc)^2]

Critical Magnetic field

Tc = (k/M)^alpha

Critical temperature on an isotope :

k = constant, M = isotopic mass,

alpha = isotope-effect exponent

After our work was completed we successfully made our high temperature superconductor. However, our Raman spectrum was inconclusive due possible to low signal or equipment failure. Our final test of the Meissner effect was the definitive test. During the test a small magnet levitaed over our superconductor.

Our experience during this summer here was enlightnen. We learned of a product which can save a lot of money and got the opportunity to make one first hand. Superconductors can be used in a wide variety of ways. We both had a wonderful time creating something so powerful and helpful to everyone.