The thermodynamic properties were reviewed by the author in 1995. A new assessment of the enthalpy of fusion has led to a revision of the thermodynamic properties of the liquid phase and although the enthalpy of sublimation at 298.15 K is retained as 377 ± 4 kJ mol^–1 the normal boiling point is revised to 3272 K at one atmosphere pressure.

The properties and glass-forming ability (GFA) of platinum- and palladium-based bulk metallic glasses (BMGs) for jewellery were introduced in Part I of this two-part review (1). Here, we will describe methods for their processing, tarnishing and corrosion resistance and consider their prospects and future developments.

Barring the presence of significant amounts of impurities, an important cause of thermoelectric inhomogeneity and therefore calibration drift of platinum-rhodium thermocouples at high temperatures is the vaporisation and transport of the oxides of Pt and Rh, which causes local changes in wire composition. By examining the vapour pressures of Pt and Rh oxides and their temperature dependence, it is shown that at a given temperature there is an optimal wire composition at which evaporation of the oxides has no effect on the wire composition, provided the vapour does not leave the vicinity of the wire. This may also have applications for Pt-Rh heater elements.

In the century since the first platinum gauze for nitric acid production was made by Johnson Matthey, the demand for nitric acid has increased considerably with its vast number of applications: from fertiliser production to mining explosives and gold extraction. Throughout the significant changes in the industry over the past 100 years, there has been continual development in Johnson Matthey’s gauze technology to meet the changing needs of customers: improving efficiency, increasing campaign length, reducing metal losses and reducing harmful nitrous oxide emissions. This article reviews the progress in gauze development over the past century and looks at recent developments.

Iridium as a barrier coating is an important area of high-temperature application. In Part I, the introduction was presented and the different deposition processes were reviewed (1). This paper, Part II, describes the texture and structure evolution, mechanical properties, growth mechanisms and applications of Ir coatings. The mechanisms of micropore formation after high-temperature treatment are also investigated in some detail.

Definitive equations are suggested to represent the variation with temperature of the densities and molar volumes of the liquid platinum group metals whilst the previously unknown initial slopes of the melting curves for iridium, rhodium and ruthenium are estimated. 1. Introduction Paradis et al. (1) summarised determinations of the densities of the liquid platinum group metals but a...

The successful use in rocket engines of iridium as a barrier coating is an important area of high-temperature application. The Ir coating must be continuous and dense in order to protect the underlying material from corrosion and oxidation. The microstructure and morphology of the coating can be effectively controlled by varying the deposition conditions. The microstructure has an important influence on the physical and mechanical properties of the coating. A number of deposition processes, which have different conditions and requirements, have been employed to produce Ir coatings on various substrate materials. Part I of this paper presents the introduction and reviews the different deposition processes, while Part II will deal with texture and structure evolution, mechanical properties, growth mechanisms and applications of Ir coatings. The mechanisms of micropore formation after high-temperature treatment will also be investigated in some detail.

Anisotropic and average intrinsic electrical resistivity measurements of ruthenium were evaluated from 10 K to 1600 K and average values above this temperature up to the melting point. For osmium average values were evaluated from 30 K to 273.15 K and anisotropic and average values above this temperature and up to 1600 K.

A novel process for the recovery of platinum group metals (pgms) from ternary alloys using a hydrocarbonyl process is proposed. The hydrocarbonyl process involves treatment of a chloride solution of the pgms with carbon monoxide at ambient pressure. The results demonstrate that the process can provide high purity pgms from a ternary platinum-rhodium-palladium alloy such as that obtained from palladium-nickel catchment alloys used with platinum-rhodium gauzes during high temperature ammonia oxidation.

An optimal platinum alloy for precision casting was developed by taking 25 possible alloying elements into consideration. In order to rank these elements an equation was designed. The ranking allowed five promising alloy compositions to be identified. From these five alloys arc melted buttons were produced and tested for homogeneity and hardness to ensure their suitability as jewellery alloys. A pyrometer was used to measure solidus temperatures. In a second iteration, the five alloys were further improved and the most promising alloys were cast and compared to a commonly used jewellery alloy: platinum-copper-gallium (PtCuGa). The comparison was based on the melting interval and on microstructural investigations, carried out by scanning electron and optical microscopy, while mechanical properties were determined by tensile testing. Additionally, optical properties such as reflectivity and colour were investigated. After the second iteration two very promising compositions were identified: PtCuFeMnCr and PtCuFePdVY.

The changes in phase state, electrical properties and microhardness of copper-55 at% palladium alloy samples with different initial states (as-quenched and deformed via severe plastic deformation (SPD)) were studied during isothermal annealing. Ordered B2-phase formation in the disordered (A1) matrix was found to occur at a significantly higher temperature than is indicated in the generally accepted phase diagram of the Cu-Pd system. Corresponding electrical resistivity is also lower than reported elsewhere for alloys of similar compositions, at ρ = (27.67 ± 0.04) × 10^–8 Ωm, making this the lowest resistivity yet reported for a Cu-Pd alloy with 55 at% Pd.

Electrical resistivity values for both the solid and liquid phases of the platinum group metals (pgms) rhodium and iridium are evaluated. In particular improved values are obtained for the liquid phases of these metals.

The use of various sintering technologies, allied to suitable powder metallurgy, has long been the subject of discussion within the global jewellery manufacturing community. This exciting, once theoretical and experimental technology is now undoubtedly a practical application suitable for the jewellery industry. All parts of the jewellery industry supply and value chains, and especially design and manufacturing, now need to become aware very quickly of just how unsettling and disruptive this technology introduction has the potential to become. This paper will offer various viewpoints that consider not only the technology and its application to jewellery manufacture but will also consider the new design potentials of the technology to the jewellery industry. It will also briefly consider how that design potential is being taught to future generations of jewellery designers at the Birmingham School of Jewellery. We shall also discuss in some detail the economics of and potential for new and different business models that this technological paradigm might offer the jewellery industry.

In the 2014 review (1) discovery circumstances for 85Ru and 86Ru were referenced only in the form of a preprint but have now been reported in the open literature (2). For the most recently discovered isotopes the discovery years for both 128Rh and 90Pd are the manuscript dates of the given references whilst for 125Ru, 130Pd and 131Pd the common discovery year corresponds to the original...

In the 2012 review (1) the isotope 209Pt was included based on a claim to its discovery by Kurcewiz et al. which was reported in a preprint (2). However when the actual paper was published (3) it was considered that the evidence for 209Pt was unsatisfactory and it was no longer included. Therefore the number of known isotopes for platinum has been amended in Table I. In addition one...

Since the 2018 review (1) one new light isotope of mass 165 (2) and four new heavy isotopes of masses 209 to 212 (3) have been identified for platinum (Table I). The heavy isotopes are only identified as being ‘particle stable’ – that is resistant to proton or neutron decay but all are expected to decay by beta decay in which an electron and anti-electron neutrino are emitted when a...

For the metals used in jewellery, high hardness and the associated scratch resistance are much sought after. Conventional crystalline alloys for jewellery are alloyed and extensively processed (thermally and mechanically) to improve hardness, but it is difficult to reach values beyond 300 HV. The advent of bulk metallic glasses (BMGs), based on precious metals and with hardness exceeding 300 HV in the as-cast state, is therefore of great interest for both jewellery and watchmaking. The non-crystalline structure of these materials not only gives high hardness, but also the opportunity to shape metals like plastics, via thermoplastic forming (TPF). For more traditional jewellery manufacture, BMGs also exhibit high-definition and near-net-shape casting. Gold-based alloys have long dominated the consideration of BMGs for jewellery as they can comply with 18 karat hallmarks. Although BMGs based on platinum or palladium possess excellent thermoplastic formability and are without known tarnishing problems, achieving useful glass-forming ability (GFA) within the more restrictive hallmarking standards typically used for jewellery (≥95 wt% platinum or palladium) is at best challenging. In this two-part review, platinum- and palladium-based BMGs are discussed, focusing on their potential application in jewellery and on the further research that is necessary.

Introduction Platinum group metals (pgms) have widespread applications as functional materials in many different industries. The applications range from catalytic surfaces or particles, sensors, biomedical imaging or drug delivery systems and thermocouples up to jewellery items that we use for special moments of our life. The pgms are used as solid bulk materials, powders, thin films,...

The down-scaling of nanoelectronic devices to ever smaller dimensions and greater performance has pushed silicon-based devices to their physical limits. Much effort is currently being invested in research to examine the feasibility of replacing Si by a higher mobility semiconductor, such as germanium, in niche high-performance metal oxide semiconductor (MOS) devices. Before Ge can be adopted in industry, a suitable contact material for the active areas of a transistor must be identified. It is proposed that platinum group metal (pgm) germanides be used for this purpose, in a similar manner as metal silicides are used in Si technology. Implementation of Ge-based technology requires a thorough understanding of the solid-state interactions in metal/Ge systems in order to foresee and avoid problems that may be encountered during integration. We present a systematic study of the solid-state interactions in germanide systems of four of the pgms: iridium, platinum, palladium and rhodium. Our approach was essentially twofold. Firstly, conventional thin film couples were used to study the sequence of phase formation in the germanide systems. Conventional thin film couples were also used to identify and monitor the dominant diffusing species during the formation of some of the germanides as these can influence the thermal stability of a device. Secondly, we observed and analysed several aspects of the lateral diffusion reactions in these four systems, including activation energies and diffusion mechanisms. Lateral diffusion couples were prepared by the deposition of thick rectangular islands of one material on to thin films of another material. Rutherford backscattering spectrometry (RBS) and microprobe-Rutherford backscattering spectrometry (μRBS) were used to analyse several aspects of the thin film and lateral diffusion interactions respectively. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were also employed.

This review briefly describes the vacuum electrostatic levitation furnace developed by JAXA and the associated non-contact techniques used to measure the density, the surface tension and the viscosity of materials. The paper then presents a summary of the data taken with this facility in the equilibrium liquid and non-equilibrium liquid phases for the six platinum group metals (pgms): platinum, palladium, rhodium, iridium, ruthenium and osmium over wide temperature ranges that include undercooled and superheated phases. The presented data (density, surface tension and viscosity of Pt, Rh, Ir, Ru and Os and density of Pd) are compared with literature values.