28-08-2017, 03:44 PM
High temperature superconductors (abbreviated as high Tc or HTS) are materials that behave like superconductors at unusually high temperatures. The first high-Tc superconductor was discovered in 1986 by IBM researchers Georg Bednorz and K. Alex Müller, who received the 1987 Nobel Prize in Physics for their important breakthrough in the discovery of superconductivity in ceramic materials.
While "ordinary" or metallic superconductors often have transition temperatures below 30 K (-243.2 ° C), they must be cooled using liquid helium to achieve superconductivity, they have been observed HTS with transition temperatures as High as 138 K (-135 ° C), and can be cooled to superconductivity using liquid nitrogen. Until 2008, only certain copper and oxygen compounds (so-called "cuprates") were believed to have HTS properties, and the term high-temperature superconductor was used interchangeably with a cuprate superconductor for compounds such as calcium copper oxide of strontium and bismuth (BSCCO) and yttrium barium copper oxide (YBCO). It is now known that various iron compounds (iron pnictides) are superconducting at high temperatures.
In 2015, hydrogen sulfide (H2S) under extremely high pressure (about 150 gigapascals) was found to undergo superconducting transition near 203 K (-70 ° C), the highest temperature superconductor known to date.
For an explanation of Tc (the critical temperature for superconductivity), see Superconductivity § Superconducting phase transition and the second bullet item of BCS theory § BCS theory successes.
While "ordinary" or metallic superconductors often have transition temperatures below 30 K (-243.2 ° C), they must be cooled using liquid helium to achieve superconductivity, they have been observed HTS with transition temperatures as High as 138 K (-135 ° C), and can be cooled to superconductivity using liquid nitrogen. Until 2008, only certain copper and oxygen compounds (so-called "cuprates") were believed to have HTS properties, and the term high-temperature superconductor was used interchangeably with a cuprate superconductor for compounds such as calcium copper oxide of strontium and bismuth (BSCCO) and yttrium barium copper oxide (YBCO). It is now known that various iron compounds (iron pnictides) are superconducting at high temperatures.
In 2015, hydrogen sulfide (H2S) under extremely high pressure (about 150 gigapascals) was found to undergo superconducting transition near 203 K (-70 ° C), the highest temperature superconductor known to date.
For an explanation of Tc (the critical temperature for superconductivity), see Superconductivity § Superconducting phase transition and the second bullet item of BCS theory § BCS theory successes.