Platinum Metals Review - Volume 35, Issue 1, 1991

High temperature superconducting oxides are being subjected to intensive investigation, designed to establish the basic mechanisms governing their superconductivity and to enable their electrical and mechanical properties to be optimised and commercial applications developed. Chemical composition, crystallography, microstructure and the concentration of point defects are all factors that have a crucial bearing on superconductivity. Progress in fabrication and thermal processing would elevate these high temperature superconducting oxides from laboratory curiosities to a position where widespread commercial use could be envisaged. Much has already been published on the use of the platinum group metals with the new superconductors. This article has been compiled from a search of the literature and indicates some of the applications that are, or could be, of commercial significance.

An International Symposium on Polymetallic Activation was held at the Università di Parma, Italy, from the 13th to 15th September 1990, aspart of a collaboration, supported by the European Commission, involving university laboratories at Strasbourg, Freiburg, Torino and Parma which carry out research on diverse aspects of polymetallic activation. An international panel of speakers presented plenary lectures giving the state of the art in their area, discussing and evaluating the results of this initiative and suggesting future actions aimed at developing and strengthening the links between European laboratories performing complementary research.

Bimetallic colloidal particles, comprising variable mol fractions of platinum and gold, function as effective catalysts for the photochemical production of hydrogen under sacrificial conditions. With increasing mol fraction of gold there is a significant decrease in the rate of hydrogenation of the reactants such that higher yields of hydrogen are attainable.

Geometrical isomers of platinum(II) and palladium(II) differ substantially in their chemical and biological properties. Under certain conditions one isomeric compound can transform into another. It is essential for chemists to be aware of the probable direction of the isomerisation process, and to predict which isomer is likely to be relatively more stable. The rules in this paper will permit such judgements to be made.