Simple Ternary Alloys Research Articles

A Review on the Advancement of Ternary Alloy Counter Electrodes for Use in Dye-Sensitised Solar Cells

A dye-sensitised solar cell (DSSC) counter electrode (CE) plays a vital role in catalysing the conversion of triiodide ( I 3 − ) to iodide ions ( I − ), thereby ensuring the completion of the repetitive cycle of electricity generation. The platinum CE, despite being the standard counter electrode in DSSCs, has drawbacks of platinum’s rarity and high cost. Platinum is an excellent redox catalyst, and consequently, it is the most sought-after metal for catalytic conversions. The huge demand for platinum in the automotive industry for vehicular catalytic converters, the pharmaceutical industry, and in oil refining, as well as other industries, has driven its price to unprecedented levels. The prohibitive price of platinum has caused newer thin film technologies, such as the DSSC which depends on the platinum CE, to be cost-ineffective, thus meaning they cannot compete with the better-established silicon-based solar cells. These problems have stagnated the development of the DSSC, which in turn has dampened larger commercialisation prospects for this thin film technology. With this in mind, this review paper focuses on recent progress in the research and development of alternative cost-effective materials to replace Pt-based CEs. Ternary alloys are amongst the possible alternatives that have been explored, yielding varied results. Alloys, especially ternary sulphides, selenides, and oxides, are attractive as alternatives as they are cheap and are easily fabricated. Ternary alloys also have a synergistic effect produced by the coexistence of two metal ions in a crystal structure, which is believed to induce greater catalytic capability, thus making them ideal cost-effective materials to replace the Pt CE in DSSCs. This review intends to highlight the performance of ternary alloy counter electrodes through the analysis of charge transfer resistance and power conversion efficiencies. Focus is also given to the restrictions and impediments to the attainment of higher power conversion efficiency in alternative CEs. The advances in fabrication of simple ternary alloys, as well as more advanced hierarchical nanostructured counter electrodes, are discussed here in detail. Results obtained to date indicate that the efficiencies of ternary alloy counter electrodes are still below that of the platinum counter electrode, and hence more research is required to enhance their efficiencies.

Structural and electrochemical properties of Ti xZr 7− xNi 10

Simple ternary alloys with formula Ti x Zr 7− x Ni 10 ( x between 0 and 2.5) were studied as a potential replacement for Laves phase alloys used in the negative electrodes of nickel metal hydride batteries. The samples were prepared by arc-melting and were not annealed. The samples retained a high degree of disorder, which contributed positively to activation and other electrochemical properties. Before hydrogenation, the alloys have a Zr 7Ni 10 orthorhombic structure mixed with some C15 and ZrO 2 secondary phases. The amount of C15 secondary phase is important to the bulk diffusion of hydrogen and the surface electrochemical kinetics. That is, the diffusion coefficient and the exchange current both increase in the presence of C15 secondary phase. The proportion of C15 secondary phase is controllable by stoichiometry design. For instance, a slightly higher Zr content reduces the C15 content. Further, as the titanium substitution level increases: (1) the lattice constants decrease; (2) the PCT plateau pressure increases; (3) activation becomes easier; and (4) the high rate dischargeability improves.

A comparison of the micromagnetic and microstructural properties of four NdFeB-type materials processed by the HDDR route

Transmission electron microscopy has been used to study the physical and magnetic microstructures of thinned sections of four different NdFeB-type alloys. Three of the materials were prepared by the solid-HDDR process and differed in that one was a simple ternary alloy, another contained Co & Ga additions and a third was appreciably richer in Nd than stoichiometric Nd 2Fe 14B 1. For the fourth material HDDR powder had been hot-pressed into a fully dense compact prior to die-upsetting. Isotropic grains with a mean size ≈300 nm were found for the first three materials whilst the die-upset material had an average grain size of ≈300×700 nm 2. All materials other than the simple ternary alloy showed strong alignment of the c-axis, the clustering of grains with similar alignment being most pronounced in the sample with Co & Ga additions. The sample with the largest region of alignment was the die-upset material, the c-axis orientation being approximately parallel to the pressing direction throughout. It was in this sample that magnetic alignment was found to be most extensive, the domains lying parallel to the mean c-axis across the whole of the visible area. Significant magnetic alignment was also found in the sample with Co & Ga whilst the Nd-rich material had relatively small areas of magnetic alignment. In the three samples with good crystallographic alignment local variations in domain wall orientation between neighbouring grains within an aligned region showed maximum variations that corresponded with the angular spread of spots in the selected area diffraction patterns.

ChemInform Abstract: Some Factors Affecting the Cycle Lives of LaNi5‐Based Alloy Electrodes of Hydrogen Batteries.

AbstractThe influence of electric, mechanical, and crystallographic properties of simple ternary alloys of general formula LaNi5‐xMx (M: Ni, Mn, Cu, Cr, Al, Co) on their cycle life in hydrogen batteries.

Some factors affecting the cycle lives of LaNi5-based alloy electrodes of hydrogen batteries

The electrode characteristics, the hydrogen equilibrium properties, the crystallographic and mechanical properties of simple ternary alloys of the type LaNi5−xMx(M ≡ Ni, Mn, Cu, Cr, AlandCo) were examined. The effect of substituting elements to improve the cycle life increased in the order: M ≡ Mn, Ni, Cu, Cr, AlandCo. The lower the capacity, the smaller the volume expansion ratio, the slower the pulverizing rate and the lower the Vickers hardness were, the longer the cycle life became. The alloy LaNi2.5Co2.5, which showed the highest durability as a negative electrode, satisfied all these requirements.

Microcrack nucleation and sustained-loading crack growth in AlLi alloys

Abstract Sustained-loading crack growth has been observed in two experimental AlLi alloys at 20 and 80 °C in circumstances where there is no strong connection between fracture and conventional stress corrosion cracking or hydrogen embrittlement. The simple ternary alloy examined (AlLiZr) was found to be much more susceptible to slow crack growth than the more complex alloy (AlLiCuMgZr) which contains additional hardening precipitates. This difference is associated with the different creep response of the alloys. Water vapour in the atmosphere was found to assist crack growth in the simple ternary alloys, but a consideration of equilibrium conditions at the crack tip shows that the crack tips are “dry” in all atmospheres apart from water-saturated air. Assistance of slow crack growth by the adsorption of water molecules is considered in terms of the formation of a Thomson-type molecular wedge.

Glass forming property of a TiZrSi system determined by temperature-composition map

The concept of T-C mapping, originally applied to binary systems, can also be applied to simple ternary alloy systems. The predicted GFCR for the TiZrSi system is in good agreement with that based on experiment. It is demonstrated that GFA of a ternary system can be predicted if the liquidus surface is determined either by experiment or by computer calculation. It has been shown that the GFCR is very sensitive to the morphology of the liquidus surface regardless of the alloy system. The only limitation of this approach is that the unpredictability of unknown ternary compounds by computer calculation leads to the construction of an erroneous liquid surface and, thereby, makes an inaccurate prediction for the glass forming ability of a system.

The formation and stability of group IVA carbides and nitrides in molybdenum

The formation of the Group IVA carbide and nitride phases in molybdenum by arc melting simple ternary alloys has been demonstrated. The threshold solute metal-interstitial atom ratios have been determined for the complete formation of the Group IVA compounds in preference to molybdenum phases. Increasing solubility with increasing temperature, up to 2100 °C, demonstrates that all these alloys show potential precipitation hardening characteristics. In some alloys (chiefly Mo-Ti-C) reversion to Mo 2C occurs above 1600 °C.

耐久磁石合金の研究(1)

This alloy consists mainly of three principal elements, namely iron, carbon and aluminium. The magnetic properties and the conditions for the heat treatment have been systimatically investigated for the simple ternary alloys, for the alloys with additions of other elements. The variation of magnetic properties and the optimum heat treatment with the compositions are given in a series of diagram.