Thallium cuprates synthesis

While this chapter has focussed on synthesis of polycrystalline samples, other aspects of the bismuth and thallium cuprate superconductors are discussed elsewhere. An introduction to synthesis and crystal growth is given in Chapter 5, and a review of the crystal chemistry of the two families is presented in Chapter... 

The sol-gel method has been conveniently employed for the synthesis of 123 compounds such as YBa2Cu307 and the bismuth cuprates. Materials prepared by such low-temperature methods have to be annealed or heated under suitable conditions to obtain the desired oxygen stoichiometry as well as the characteristic high Tc value. 124 cuprates, lead cuprates and even thallium cuprates have been made by the sol-gel method the first two are particularly difficult to make by the ceramic method. Coprecipitation of all the cations in the form of a sparingly soluble salt such as carbonate in a proper medium (e.g. using tetraethyl-ammonium oxalate), followed by thermal decomposition of the dried precipitate has been employed by many workers to prepare cuprates. 

This chapter presents an overview of our understanding of phase relationships and a summary of synthetic techniques for the synthesis of phase-pure superconducting samples in the bismuth-and thallium-based families of high Tc cuprate superconductors. 

The following sections will outline specific methods for the synthesis of Bi- and Tl-based cuprate superconductors. Because the synthetic methods and historical evolution of the compounds are different, the bismuth and thallium families are described separately. 

It should be emphasized that thallium is present in its univalent state in the cuprate system. This fact, in principle, means that no electrochemical process involving thallium takes place in the course of synthesis, and only copper undergoes... 

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