{"id":5865,"date":"2017-05-25T14:55:40","date_gmt":"2017-05-25T14:55:40","guid":{"rendered":"https:\/\/www.techopedia.com\/definition\/superconductor\/"},"modified":"2024-03-14T16:21:51","modified_gmt":"2024-03-14T16:21:51","slug":"superconductor","status":"publish","type":"definition","link":"https:\/\/www.techopedia.com\/definition\/9582\/superconductor","title":{"rendered":"Superconductor (Superconductivity)"},"content":{"rendered":"

What is a Superconductor?<\/span><\/h2>\n

A superconductor is a material that permits electric current to pass through it without experiencing any energy loss. Standard conductors, like copper wires, possess a level of electrical resistance<\/a> — this is what causes them to heat up when an electric current passes through them.<\/p>\n

In contrast, superconductors exhibit zero resistance, so they do not heat up when current flows through them. This phenomenon, known as superconductivity<\/strong>, is deeply rooted in quantum mechanics<\/a>.<\/p>\n

History<\/span><\/h2>\n

The concept of superconductivity was first discovered in 1911 by Heike Kamerlingh Onnes, a Dutch scientist who was studying low-temperature physics. Onnes discovered that as he cooled mercury to temperatures just a few degrees above absolute zero,\u00a0mercury was able to conduct electric current without any resistance or energy loss.<\/p>\n

Onnes\u2019 experiments and discoveries became part of the foundation that later physicists built upon: At extremely low temperatures, quantum mechanical effects become more pronounced, and the behavior of electrons becomes governed by quantum laws rather than classical physics.<\/p>\n

How Superconductors Work<\/span><\/h2>\n

Most materials need to be in a very low-energy state to be superconductive.<\/span><\/p>\n

When an electric current passes through a standard conductor like copper at room temperature, the electrons that are navigating through the copper\u2019s lattice of atoms can interact with vibrations in the lattice. This interaction results in resistance, which leads to the dissipation of energy in the form of heat.<\/p>\n

When an electric current passes through a conductor at an extremely cold temperature, however, the electrons can form pairs that move through the conductor\u2019s lattice of atoms as if they were a single entity. This severely reduces or even eliminates the electrons\u2019 ability to interact with vibrations in the lattice.<\/p>\n

This lack of interaction with lattice vibrations (phonons) is an important factor that contributes to the absence of electrical resistance in superconductors.<\/p>\n

Type I and Type II Superconductors<\/h3>\n

There are two categories of superconductors: Type I and Type II. A Type I superconductor is comprised of conductive elements that have a critical temperature ranging from 0.000325 K to 7.8 K at standard pressure. In contrast, Type II superconductors are comprised of mostly metallic alloys and compounds which become superconductive at higher temperatures. <\/span><\/p>\n

The main difference between Type I and Type II, however, is how they respond to magnetic fields<\/a>. Type I superconductors expel all magnetic flux<\/a> below a certain critical field, while Type II superconductors can accommodate some magnetic flux within specific ranges.<\/p>\n

The Meissner effect, in which a superconductor will expel virtually all magnetic fields from its interior when cooled below a certain critical temperature, is a phenomenon observed in both Type I and Type II superconductors. However, the Meissner effect behaves differently in Type I and Type II superconductors.<\/p>\n