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Background: Superconductors are materials that offer zero resistance to the flow of electricity. In other words, a superconductor will not get hot as more and more electricity passes through it, thus, eliminating energy loss over distance. The phenomenon was first observed in 1911 by Dutch physicist Heike Kamerlingh Onnes after he had cooled mercury to 4° Kelvin (-452°F, -269°C), the temperature of liquid helium. To induce superconductivity in pure mercury, it was necessary for Onnes to come within 4 degrees of Absolute Zero, the coldest temperature that is theoretically attainable. By experimentation, he discovered other materials would also exhibit superconductivity, each at its own point known as the transition temperature, or Tc. His research won him a Nobel Prize in 1913.
Twenty years later, Walter Meissner and Robert Ochsenfeld discovered that superconducting materials would energetically repel a magnetic field. This phenomenon became known as diamagnetism but is often referred to as the Meissner effect.
In the decades that followed, other superconducting materials were discovered such as niobium-nitride, vanadium-silicon, and an alloy of niobium and titanium, to name a few, but there was a problem. It seemed every scientist had a hypothesis to account for superconductivity within their particular material, but none was able to provide a single unifying theory that spanned all the compounds. What explained one superconductor, unraveled with the next.
To make matters worse, in the 1980’s a second type of material was found to exhibit superconductivity. Alex Müller and Georg Bednorz, working at the IBM Research Laboratory in Rüschlikon, Switzerland, created a brittle ceramic compound that superconducted at the highest temperature then known: 30°K (-405°F, -243°C). These became known as Type 2 superconductors. A unified theory of superconduction seemed even further away.
Research into Type 2 materials continued into the next century as more and better superconductors were devised, each striving to push the transition temperature ever higher. The world’s first superconducting power transmission lines were put into place in the last decade of the 20th century and in 2010, the highest Tc attained by any Type 2 was achieved, 191°K (-116°F, -82°C), a temperature easily maintained using liquid nitrogen. However, it took the discovery of Type 3 materials before the use of superconductors became widespread.
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