Copper-germanium alloy

Youdelis WV and Youdelis RA (1981) Silver-copper-germanium alloys (potential for oral restorations). Can Dent Assoc J 47 101-106. 

The converter consists of 1,536 pairs of thermopiles made of silicon-germanium alloy (Si 85% by mass, Ge 15% by mass) with n- and p-conductivity. Each module of 16 thermopiles is mounted on the inner surface of the hermetically sealed steel vessel. To provide for a good contact on the reactor heating, each module is pressed on the reflector by gas bellows elements. On the hot side, the keyboard consists of molybdenum plates, on the cold one - of copper bridges. To prevent an electric contact (shorting), insulating plates of beryllium oxide are used on the hot and cold sides. The excess heat is removed from the reactor-converter by shaped enamel-coated copper fins with an emissivity of at least 0.9 (O Fig. 59.2). 

In substitutional metallic solid solutions and in liquid alloys the experimental data have been described by Epstein and Paskin (1967) in terms of a predominant frictional force which leads to the accumulation of one species towards the anode. The relative movement of metallic ion cores in an alloy phase is related to the scattering cross-section for the conduction electrons, which in turn can be correlated with the relative resistance of the pure metals. Thus iron, which has a higher specific resistance than copper, will accumulate towards the anode in a Cu-Fe alloy. Similarly in a germanium-lithium alloy, the solute lithium atoms accumulate towards the cathode. In liquid alloys the same qualitative effect is observed, thus magnesium accumulates near the cathode in solution in bismuth, while uranium, which is in a higher Group of the Periodic Table than bismuth, accumulated near the anode in the same solvent. 

Uses. In metallurgy for hardening copper and lead alloys to prepare GaAs for electronic devices, doping agent in germanium and silicon solid state products, special solders. 

The supplanting of germanium-based semiconductor devices by silicon devices has almost eliminated the use of indium in the related alloy junction (see Semiconductors). Indium, however, is finding increased use in III—V compound semiconductors such as indium phosphide [22398-80-7] for laser diodes used in fiber optic communication systems (see Electronic materials Fiber optics Light generation). Other important indium-containing semiconductors include indium arsenide [1303-11-3], indium antimonide [1312 -1-0], and copper—indium—diselenide [12018-95-0]. 

Effect of Increasing Valency of Solute. It has been found that when size-factors are favourable extended solid solutions are most lilcely to be formed when the metals concerned have atoms with the same number of outer-layer electrons, i.e. when they have the sa ne valency. When size-factors arc favourable and valencies unequal tin4 extent of solid solubility will decrease as the difference between the respective valencies increases. To examine the effect of the valency-factor we may consider the extent of the solid solubility in copper ((1u).of the favourable size-factor but increasing valency metals, zinc (Zn), gallium (Ga), germanium (Ge) and arsenic (As), and in silver (Ag) of the corresponding favourable size-factor metals, cadmium (Cd), indium (In), tin (Sn) and antimony (8b). The necessary atomic diameters and valency data (vide p. bl), and the results of experimental work on these1 alloys, as far as the primary solid solutions are concerned, an1 summarised in Fables IX (a) and (h). 

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