Topic: Superconductors Please write down the main points discussed 1.5 High-Temp
ID: 1046946 • Letter: T
Question
Topic: Superconductors
Please write down the main points discussed
1.5 High-Temperature Superconductors In 1986, J. G. Bednorz and K. A. Müller [22] reported that the metal oxide ce- ramic La2-BarCuO4 becomes superconducting above 30 K. Up to that point, the compound Nb3Ge had the highest critical temperature of 23.2 K [23]. The supercon ductivity of La2-Ba,CuO iniiated a flurry of research on a new family of materials referred to as high-temperature superconductors. M. K. Wu et al. [24] found that an other copper oxide YBa2Cu3O (YBCO) is superconducting with a critical tempera- ture of 92 K. YBCO was the first superconductor found to have a critical temperature above the boiling point of nitrogen at 77 K. Many more copper-oxide, or cuprate, high temperature superconductors were subsequently discovered including Bi2Sr2CaCu2Os with T?s 105 K [25] , TI2BwCa2Cu3Ôn with T,s 120 K [26], and HgBwChCu308 with the highest critical temperature to date of T. 134 K [27]. The existence of many copper oxide superconductors is a consequence of the versatility of copper ox- ide in forming perovskite structured oxides when combined with alkaline earth, rare earth, and lone-pair ion oxides [28]. The general structure of cuprate superconductors consists of layers of Cu02 separated by intermediary AO-type layers and MO2-type layers stacked in different sequences [28] with "A" representing alkaline earth metals and "M" representing a transition or other metals. Certain iron-based materials are also high-temperature superconductors. Iron-based superconductors contain layers of iron and elements from group 15 of the periodic table called pnictogens. Examples include the family ReFeAs01-5 (Re = Sm, Nd, Pr, Ce, La) with critical temperatures ranging from 26 K to 55 K [29]. All high-temperature superconductors known at the present time are classified as type II superconductorsExplanation / Answer
The main points discussed are: