Platinum Metals Review - Volume 47, Issue 4, 2003

Shape memory alloys (SMAs) are materials that can change their shape at a specific temperature and are used in applications as diverse as sensors, temperature sensitive switches, force actuators, fre-safety valves, orthodontic wires, fasteners, and couplers. The possible advantages offered by platinum-based SMAs involving the metals: iron, aluminium, gallium, titanium, chromium, and vanadium, are considered here and the likely systems upon which such alloys might be based are assessed. It is suggested that the most promising candidate systems are ternary-alloyed variations of the Pt3Al and PtTi phases, although SMAs based on PtFe3 have potential for low temperature applications. It appears possible to engineer a shape memory transition in the (Pt, Ni)Ti system anywhere between room temperature and 1000°C, a versatility which is probably unique among all known SMAs.

A new process called AquaCat^® for the recovery of precious metals from spent heterogeneous and homogeneous catalysts is described. The process has two stages, the first stage is to determine the precious metal content of a spent heterogeneous catalyst using new direct sampling technology. The second stage involves supercritical water oxidation, during which the carbonaceous material is converted into less noxious compounds, leaving the precious metals as their oxides.

This paper is the second in a series of reviews of work performed that led up to the discoveries of the isotopes of the six platinum group elements. The first review, on platinum isotopes, was published in this Journal in October 2000 (1). Here, a brief history of the discovery of the thirty-six known isotopes of iridium in the sixty-seven years from the first discovery in 1934 to 2001 is considered in terms of the discoverers.

The years 2002 to 2004 mark the bicentenaries of the discoveries of rhodium, palladium, iridium and osmium. Two remarkable people were responsible for their discoveries – William Hyde Wollaston (1766–1828) the discoverer of rhodium and palladium, and his friend Smithson Tennant (1761–1815) the discoverer of iridium and osmium. This and a subsequent paper will seek to retell the stories of their discoveries, and to indicate the growing usefulness of the metals throughout the nineteenth century to their importance today. In this first part we will discuss Wollaston and his discoveries. Part II, to be published in a later issue, will complete the story with Tennant’s discoveries of the more intractable elements iridium and osmium.