Indium elemental properties

The platinum-group metals (PGMs), which consist of six elements in Groups 8— 10 (VIII) of the Periodic Table, are often found collectively in nature. They are mthenium, Ru rhodium, Rh and palladium, Pd, atomic numbers 44 to 46, and osmium. Os indium, Ir and platinum, Pt, atomic numbers 76 to 78. Corresponding members of each triad have similar properties, eg, palladium and platinum are both ductile metals and form active catalysts. Rhodium and iridium are both characterized by resistance to oxidation and chemical attack (see Platinum-GROUP metals, compounds). 

The low-melting-point (157 °C), silver metal is mainly used in alloys to decrease the melting point. Combined with tin, lead, and bismuth to produce soldering metal for wide temperature ranges. The element is highly valuable in the electronics age as its unique properties are ideal for solar cells, optoelectronics, and microwave equipment. The arsenide is used in lasers and is also suitable for transistors. ITO (indium tin oxide) is a transparent semiconductor with wide application in displays, touchscreens, etc. In the household, indium as an additive prevents the tarnishing of silverware. Some electronic wristwatches contain indium batteries. 

A note of caution is necessary when deahng with these materials. It is not trivial to distinguish between CuInS(Se)2 and some phases of Cu—S(Se). Diffraction and optical properties may be similar. Elemental analysis is particularly important to verify inclusion of indium in the films and in the correct ratio. A fingerprint of the chalcopyrite XRD is the presence of a weak peak at 26 = 17-18°, corresponding to the (101) chalcopyrite reflection. This is often not seen, although this could be either because the deposit is not chalcopyrite or because weak peaks are usually not seen in nanocrystaUine materials with particularly small crystal size. 

Other important physical properties of indium arc given under Chemical Elements. 

The periodic trends in main-group elements become apparent when we compare the binary compounds they form with one specific element. All the main-group elements, with the exception of the noble gases and, possibly, indium and thallium, form binary compounds with hydrogen, so these hydrides can be examined to look for periodic trends. We meet the binary hydrides several times in this chapter and the next, so, at this stage, we confine the discussion to a brief survey and see how their properties reveal periodic behavior. 

The chemical properties of indium are typical of those of Group 13 of the Periodic Table. Most of indium s oxides, salts, and compounds involve the +3 oxidation state (e.g., In203, In[N03]3> and InCl3) many of these compounds are electron-pair acceptors, forming addition compounds with donor molecules (e.g., InBr3 py, py = pyridine). Neutral, cationic, and anionic complexes are also known. Several interesting compounds are derived from the +1 and +2 oxidation states of the element. 

Boron, aluminum, gallium, indium, and thallium are members of group 13 of the Periodic Table. Some important properties of these elements are given in Table 13.1.1. 

Silicon, diamond, and metal deposition are all examples of elemental deposition. Compounds, particularly oxides, are also deposited by chemical vapor deposition. Some of the important oxides deposited as thin films include SiC>2, BaTiC>3, LiNbC>3, YBa2Cu30,. indium-doped SnC>2, and LiCoC>2. These materials have properties such as superconductivity or lithium ionic conductivity that make their production as thin films a much-studied area of research. If the oxide is to be deposited on the bare metal (e.g., depositing SiC>2 onto Si), chemical vapor deposition is not really needed. Controlling the oxygen partial pressure and temperature of the substrate will produce the oxide film Whether the film sticks to the substrate is another question The production of SiC>2 films on Si is an advanced technology that the integrated-circuit industry has relied on for many years. Oxide films on metals have been used to produce beautiful colored coatings as a result of interference effects (Eerden et al., 2005). 

The Group 13 elements have the same relationship to the alkaline earth elements that the alkaline earth elements have to the alkali metals, that is, the group properties are modified by the presence of a third valence electron. The elements of Group 13 are boron, aluminum, gallium, indium, and thallium. Except for boron, which may be classified as a semimetal, these elements tend to show metallic properties. 

In 1991, Li and Chan reported the use of indium to mediate Barbier-Grignard-type reactions in water.12 The work was designed on the basis of the first ionisation potentials of different elements, in which indium has the lowest first ionisation potential relative to the other metallic elements near it in the periodic table. On the other hand, indium metal is not sensitive to boiling water or alkali and does not form oxides readily in air. Such special properties of indium indicate that it is perhaps a promising metal for aqueous Barbier-Grignard-type reactions. Indeed, it appears that indium is the most reactive and... 

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