Startling Discovery by Muller and Bednorz

As pointed out above in Section 4.1, the parent compound La2Cu04 was studied (115)(117)( 126X136) extensively between 1965 and 1980. Most of these investigations, however, were directed 

Alkaline-earth substitution in LajCuC was also investigated (121)(128)(131) during the early 1970 s in the U.S.S.R., India, and Japan, but unfortunately, these materials were never investigated at sufficiently low temperatures for detection of their superconducting properties. This oversight resulted in a 16 year delay in the discovery of high temperature superconductivity in copper-oxide compounds. 

Prior to the events of 1986-87, a substantial effort in the solid state chemistry of simple and complex copper oxides had been established in France. As early as 1980, structural chemists at Caen, under the direction of Michel and Raveau, studied the synthesis and structure of several ternary, quaternary, and multinary Cu-O compounds. 

A comprehensive report which focussed on the La2 xSrxCu O4-x/2+S ser es was published (139) in 1983 by this research group. In this broad review they reported the magnetic and electrical transport properties of these mixed-valent copper oxides in the temperature range 120-650 K. They concluded that the original semiconducting behavior in La2Cu04 transformed to semi-metallic behavior as the Cu3+ content increased with Sr-substitution. No experiments were conducted below 50 K, and therefore superconductivity was not observed. Three series of compounds, with 0.00 x 1.20 were 

During this same period of time, Michel and Raveau reported (141) the synthesis of La3BasCu6014+y, a new compound having some close relationship to the perovskite structure. This compound was the precursor to a variety of different copper-oxide derivatives a more complete paper on its structure was published (142) in 1987, and the recent physical property measurements indicated (143) no superconductivity in either the quenched or oxygen-annealed phases. 

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