La-Cu-O system

This stood as a maximum until 1986, when Bednorz and Muller reported the possibility of superconductivity in the Ba-La-Cu-O system. Soon, confirmation of the superconducting phase La2. Ba Cu04 was heralded by many other laboratories worldwide, and a record of 35 K was achieved with x = 0.4. 

Bednorz JG, Muller KA (1986) Possible high T c superconductivity in the Ba-La-Cu-O system. Z Phys B Condens. Matter 64 189-193... 

High-7c Superconducting Oxides Chemical Composition. Bednorz and Muller carried out a series of investigations aiming to enhance the electron-phonon interaction in superconducting oxides. As a result, they found superconductivity at around 30 K intheBa—La—Cu—O system [2.12]. These compounds... 

Oxide superconductors have been known since the 1960s. Compounds such as niobium oxide [12034-57-0] NbO, TiO, SrTi02, and AWO, where A is an alkah or alkaline earth cation, were found to be superconducting at 6 K or below. The highest T observed in oxides before 1986 was 13 Kin the perovskite compound BaPb Bi O, x = 0.27. Then in 1986 possible superconductivity at 35 K in the La—Ba—Cu—O compound was discovered (21). The compound composition was later determined to be La 85 A the Y—Ba—Cu—O system was pubUshed in 1987 and reported a transition... 

The entire situation changed when Bednorz and Muller (1986) discovered 30 K superconductivity in a cuprate of the La-Ba-Cu-O system. This broke the apparent 23 K barrier for the T. Since 1986, a variety of cuprates have been synthesized and characterized with the maximum reaching 150K. The cuprates are unusual in many ways and do not seem to follow the BCS model. We shall discuss the cuprates at length later in Chapter 7. Alkali and alkaline-earth derivatives of Cgo (buckminsterful-lerene) exhibit superconductivity with a maximum of 35 K. We shall examine these... 

Since the discovery of high temperature superconductivity (T > 30 K) in the La-Ba-Cu-O system hundreds of high temperature superconducting oxides have been found, with the record Tc of 164 K in Hg-1223 under high pressure. According to their major chemical difference, these superconductors can be classified into six major categories K2Nip4-type cuprates, rare-earth-based cuprates, bismuth-based cuprates, thallium-based cuprates, mercury-based cuprates, and other cuprates. Details of every superconductor are not presented, but at least one typical composition of each major type will be discussed in detail. Interested readers can read the relevant literature to get specific information on other systems. 

In this chapter we have selected a number of case studies to show how atomistic lattice simulations can be used to investigate the structural and defect chemistry of a wide range of high-7 cuprates. Space limitations have necessarily restricted the number of examples to a small range of compounds, chiefly from the La Cu-O, Nd-Cu-O, Y Ba Cu O and Sr-Cu-O systems. 

IV. PREPARATION OF LARGE-GRAIN CRYSTALS A. Single Crystals of La-Sr-Cu-O System... 

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