Copper lanthanum strontium oxide

CaCu2La 06Sro,4. Calcium copper lanthanum strontium oxide (CaCujLa,6Sro,406). [129161-55-3[. 30 197... 

CuLa02.5-i57. Copper lanthanum oxide (CuLa02.5.2.57). )158188-95-S). 30 221 CuLa025.2 8, Copper lanthanum oxide (CuLab2.6.2.g), (158188-94-4). 30 221 CuLa02g.3. Copper lanthanum oxide (CuLa02,8-3). [158188-93-3). 30 219 CuLaj 8504870,15. Copper lanthanum strontium oxide (CuLa ,85870,1504). [107472-96-8], 30 193... 

Lai,g5Cu04Sro,i5. Copper lanthanum strontium oxide (CuLai gjSrg 15O4), [107472-96-81,30 193 La2B6MgOi8Sr5, Boric acid (H3BO3). 

Copper lanthanum strontium oxide (CuLaj g5Sro 15O4), 30 193 [108159-17-7), Cobalt sodium oxide (CoNao,602), 30 149... 

The superconducting oxides include both perovskites and Ruddlesden-Popper compounds which have an orthorhombic arrangement of cubic cells, alternatively of the perovskite and sodium chloride structures. The common feature of all of these is the presence of copper as a major component. The first ceramic superconductor was a lanthanum-strontium substituted cuprate (Lai Sr Cu04 z), which is a perovskite, but subsequently the inter-oxide compound Y203 2BaO 3CuO, commonly referred to as a 123 compound, was shown to have superior performance. The speculation concerning the conduction mechanism is that this involves either Cu3+-Cu2+ positive hole... 

It soon became apparent, once the structure of the yttrium compound was bared, that either or both of two central features might account for superconductivity at those record-high temperatures. One was the puckered, two-dimensional plane of copper and oxygen atoms ilar to the flat plane seen earlier in the structure of another superconductor, made of lanthanum, strontium, and copper oxide, that became superconducting at around 40° K. The other was unexpected the one-dimensional chain of copper and oxygen atoms, a sequence unknown in earlier superconductors. The challenge was fairly clear to both theorists and experimentalists. Were the planes or the chains responsible for superconductivity above 90° K ... 

In 1986, the highest temperature at which any material became superconducting, i.e., the ability to conduct electricity with virtually no loss, was around —250°C, or 23 K. In that year a breakthrough came when Bednorz and Muller, shattered the record by demonstrating that a layered lanthanum, strontium copper oxide became superconducting at the relatively balmy temperature of 46 K. This discovery provoked a worldwide interest in the subject, and a few months later the record was again almost doubled, to about 90 K. The record today is in excess of 120 K. 

Wang, H. H. Carlson, K. Douglas Geiser, Urs et al.. Comparison of carbonate, citrate, and oxalate chemical routes to the high-Tc metal oxide superconductors, lanthanum strontium copper oxide, La2-xSrxCu04. Inorg. Chem. 1987, 26, 1474-1476. 

Research chemists found that they could modify the conducting properties of solids by doping them, a process commonly used to control the properties of semiconductors (see Section 3.13). In 1986, a record-high Ts of 35 K was observed, surprisingly not for a metal, but for a ceramic material (Section 14.24), a lanthanum-copper oxide doped with barium. Then early in 1987, a new record T, of 93 K was set with yttrium-barium-copper and a series of related oxides. In 1988, two more oxide series of bismuth-strontium-calcium-copper and thallium-barium-calcium-copper exhibited transition temperatures of 110 and 125 K, respectively. These temperatures can be reached by cooling the materials with liquid nitrogen, which costs only about 0.20 per liter. Suddenly, superconducting devices became economically viable. 

Benschop, F.J.M., Brom, H.B. and Maaskant, W.J.A. (1992) A lead NMR study of the superconductor lead strontium lanthanum copper oxide Pb2Sr09La11Cu206A. Physica C, 201, 109—118. 

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