Alloys quaternary

There are hundreds of semiconductor materials, but silicon alone accounts for tire overwhelming majority of tire applications world-wide today. The families of semiconductor materials include tetraliedrally coordinated and mostly covalent solids such as group IV elemental semiconductors and III-V, II-VI and I-VII compounds, and tlieir ternary and quaternary alloys, as well as more exotic materials such as tire adamantine, non-adamantine and organic semiconductors. Only tire key features of some of tliese materials will be mentioned here. For a more complete description, tire reader is referred to specialized publications [6, 7, 8 and 9]. 

III-V compound semiconductors with precisely controlled compositions and gaps can be prepared from several material systems. Representative III-V compounds are shown in tire gap-lattice constant plots of figure C2.16.3. The points representing binary semiconductors such as GaAs or InP are joined by lines indicating ternary and quaternary alloys. The special nature of tire binary compounds arises from tlieir availability as tire substrate material needed for epitaxial growtli of device stmctures. 

Heterostructures and Superlattices. Although useful devices can be made from binary compound semiconductors, such as GaAs, InP, or InSb, the explosive interest in techniques such as MOCVD and MBE came about from their growth of ternary or quaternary alloy heterostmctures and supedattices. Eor the successful growth of alloys and heterostmctures the composition and interfaces must be accurately controlled. The composition of alloys can be predicted from thermodynamics if the flow in the reactor is optimised. Otherwise, composition and growth rate variations are observed... 

The britdeness of metals is frequently iacreased by the addition of sodium to form alloys. The metals vary ia their abiUty to dilute the natural reactivity of sodium. Most biaary alloys are unstable ia air and react with water. Ternary and quaternary alloys are more stable. 

Phase diagrams are mostly determined by thermal analysis. We now discuss one-component systems to show how it works. The more complicated diagrams for binary, ternary or quaternary alloys are determined by the same method. 

For practical as well as fundamental reasons, there has been considerable interest in the deposition of alloys containing metals such as W, Mo, and Sn. In their pure forms, these metals do not catalyze the oxidation of the usual electroless reducing agents. Therefore, their mechanism of codeposition is intriguing, and developing an understanding of it should help to better understand the mechanism of electroless deposition as whole. Obvious questions in ternary and quaternary alloy deposition include the effect of the third or fourth element containing ions in solution on the rate of electroless deposition, as well as on the P and B contents in the case of alloys such as Ni-P and Ni-B. 

In any case, going back to the beginning of the past century we may mention the pioneering investigation carried out by Parravano and Sirovich (1912) and Parravano (1914) in the determination by thermal analysis of the phase diagrams of quaternary alloy systems, such as Cu-Fe-Mn-Ni, Bi-Cd-Pb-Sn, Ag-Au-Cu-Ni. 

An extension of the application of these maps to the systematic description of certain groups of ternary alloys has been presented also by Pettifor (1988a, b). Composition averaged Mendeleev numbers can be used, for instance, in the description of pseudo-binary, ternary or quaternary alloys. All these maps show well-defined domains of structural stability for a given stoichiometry, thus making the search easier for new ternary or quaternary alloys with a particular structure type (and which, as a consequence, may have the potential of interesting properties and applications (Pettifor 1988a, b)). 

Hardfaeing and Wear-resistant Alloys. These materials, essentially quaternary alloys of cobalt chromium, tungsten (or molybdenum) and carbon, are widely used for industrial hardfaeing purposes. They can be deposited by welding techniques, sprayed on as powders, or produced as separate castings. By using the weld deposition technique, a highly alloyed heat-, wear-, and corrosion-resistant surface can be applied to a... 

Cu3Si, CusSi and Cu. At lower temperatures the only product is Cu. Intermetallics have an important effect on the direct process. For example, the activating effect of aluminum disappears when added as the quaternary alloy Fe4SigAlgCa but an increase in selectivity is noted when the ternary alloy is present. Aluminum added as the ternary alloy SiyAlsFes, Al3Si2Fe and Al2Si2Ca favors activity but decreases selectivity. 

To what extent the films grown electrochemically have decisive advantages over those grown with other techniques is not clear yet. However, one can see that great variety (e.g., ternary and quaternary alloy formations) is possible, and the availability of potentiostatic control and nonaqueous solutions may be helpful. 

It is not surprising that the alloy combinations being claimed as improvements are similar to those that have been claimed in the United States previously. In most instances, quaternary alloy combinations have been claimed that utilize platinum with one or more of the 4th period-group 8 transition metals, together with a 4th element that modifies the metallurgical behavior of the alloy. 

FACES (ternary alloys, 28x6) 224 INNER (quaternary alloys, 56x4)... 

L9 was built from the combination of five elements (Pt, Ru, Os, Ir, and Rh) in a quaternary phase diagram (combinations of up to four elements from the five possible 57). Thequaternary phase diagram can be represented by a 10 x lOx lOx 10 tetrahedron (Fig. 11.12), where the 4 vertices represent the pure elements, the 48 positions on the edges (6 x 8) represent the binary alloys, the 112 positions on the faces (4 x 28) represent the ternary alloys, and the 56 inner positions represent the quaternary alloys to give a total of 220 different compositions. The addition of a fifth element increased the library composition by 1 (element) -1- 32 (4 x 8, binary alloys) + 168 (6 x 28, ternary alloys) -1- 224 (4 x 56, quaternary alloys) = 425 different compositions, giving a total number of 645 library individuals for L9 (Fig. 11.12). 

Up to now, research on ternary metal hydrides based on magnesium and alkaline or alkaline earth metals has not produced alloys with practical hydrogen storage characteristics [250]. However, study of quaternary alloys is a new fleld that is worth investigating and could give practical hydrogen storage systems [250]. 

As their name implies, shape-memory alloys are able to revert back to their original shape, even if significantly deformed (Figure 3.24). This effect was discovered in 1932 for Au-Cd alloys. However, there were no applications for these materials until the discovery of Ni-Ti alloys (e.g., NiTi, nitinol) in the late 1960s. As significant research has been devoted to the study of these materials, there are now over 15 different binary, ternary, and quaternary alloys that also exhibit this property. Other than the most common Ni-Ti system, other classes include Au-Cu-Zn, Cu-Al-Ni, Cu-Zn-Al, and Fe-Mn-Si alloys. 

The BFS method has been applied to a variety of problems, ranging from the determination of bulk properties of solid solution fee and bee alloys and the defeet strueture in ordered bee alloys [28] to more speeifie applieations ineluding detailed studies of the strueture and eomposition of alloy surfaees [29], ternary [30] and quaternary alloy surfaees and bulk alloys [31,32], and even the determination of the phase strueture of a 5-element alloy [33]. Previous appheations have foeused on fundamental features in monatomie [26] and alloy surfaces [29] surface energies, reconstructions, surface structure and surface segregation in binary and higher order alloys [34,35] and multilayer relaxations [36,37]. While most of the work deals with metallic systems, the lack of restrictions on the type of system that can be studied translated into the extension of BFS to the study of semiconductors [38]. 

Volume 170 of the Journal of Crystal Growth (1977) is devoted to MOCVD, with many papers compounds of groups II-VI. A discussion of the chemistry of precursors is P. O Brien, M, A. Malik, M. Chunggaze, T. Trindade, J. R. Walsh (p. 23). An illustration of the power of the technique to grow the quaternary alloy ZnMgSSe is the paper by M. Heuken, J. Sollner, W. Taudt, S. Lampe, H. Hamadeh (p. 30). 

Photographs 4 and 5, Plate IIIa, refer to the ternary and quaternary alloys containing about 3 % and 11 % of copper respectively. 

Each of alloying additions contributes to increased hot hardness of ternary and quaternary alloys. Zr and / -elements have this effect at all the temperatures studyied, and V and Nb act up to 400°C for ternary alloys or to 600°C for quaternary alloys. 

There exists many III-V ternary and quaternary alloys, and we just mention here the In, ( a ,As family, that has many applications in microelectronics. The variation of the direct band gap of these alloys at RT is given by ... 

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