Antimony property

Shanthi E, Dutta V, Baneqee A and Chopra K L 1980 Electrical and optical properties of undoped and antimony-doped tin oxide films J. Appi. Rhys. 51 6243-51... 

Bromine has a lower electron affinity and electrode potential than chlorine but is still a very reactive element. It combines violently with alkali metals and reacts spontaneously with phosphorus, arsenic and antimony. When heated it reacts with many other elements, including gold, but it does not attack platinum, and silver forms a protective film of silver bromide. Because of the strong oxidising properties, bromine, like fluorine and chlorine, tends to form compounds with the electropositive element in a high oxidation state. 

Acryhc and modacryhc fibers are sold mainly as staple and tow products with small amounts of continuous filament fiber sold in Europe and Japan. Staple lengths may vary from 25 to 150 mm, depending on the end use. Eiber deniers may vary from 1.3 to 17 dtex (1.2 to 15 den) 3.2 dtex (3.0 den) is the standard form. The appearance of acryhcs under microscopical examination may differ from that of modacryhcs in two respects. Eirst, the cross sections (Eig. 1) of acryhcs are generally round, bean-shaped, or dogbone-shaped. The modacryhcs, on the other hand, vary from irregularly round to ribbon-like. The modacryhcs may also contain pigment-like particles of antimony oxide to enhance their flame-retardant properties. 

Table 2. Properties of Antimony Pentoxide and Sodium Antimonate...

Sodium Antimonate. Sodium antimonate [15593-75-6] Na SbO, another antimony synergist of commercial importance, has an antimony content of 61—63 wt % and a bulk density of 39.4—46.4 kg/m. Properties are given in Table 2. It is made by oxidizing antimony trioxide using sodium nitrate and caustic. It is a white powder and has a pH of around 9—11 when dissolved in water. 

Another approach to durable press—flame retardancy uses a combination of a cross-linking system, antimony(III) oxide, and a bromine-containing reactive additive, namely dibromoneopentyl glycol, to achieve dual properties (120,121). 

Properties. Antimony pentafluoride [7783-70-2], SbF, is a colorless, hygroscopic, very viscous liquid that fumes ia air. Its viscosity at 20°C is 460 mPa-s(=cP) which is very close to the value for glycerol. The polymerization of high purity SbF at ambient temperature can be prevented by addition of 1% anhydrous hydrogen fluoride, which can be removed by distillation prior to the use of SbF. The pure product melts at 7°C (11), boils at 142.7°C,... 

Table 1. Mechanical Properties of Lead—Antimony Alloys ...

Excellent antifriction properties and good hardness (qv) make lead—antimony—tin alloys suitable for journal bearings. The alloys contain 9—15 wt % antimony and 1—20 wt % tin and may also contain copper and arsenic, which improve compression, fatigue, and creep strength important in bearings. Lead—antimony—tin bearing alloys are Hsted in ASTM B23-92 (7). 

Rea.ctivity ofLea.d—Ca.lcium Alloys. Precise control of the calcium content is required to control the grain stmcture, corrosion resistance, and mechanical properties of lead—calcium alloys. Calcium reacts readily with air and other elements such as antimony, arsenic, and sulfur to produce oxides or intermetaUic compounds (see Calciumand calciumalloys). In these reactions, calcium is lost and suspended soHds reduce fluidity and castibiUty. The very thin grids that are required for automotive batteries are difficult to cast from lead—calcium alloys. 

Wrought lead—calcium—tin alloys contain more tin, have higher mechanical strength, exhibit greater stabiUty, and are more creep resistant than the cast alloys. RoUed lead—calcium—tin alloy strip is used to produce automotive battery grids in a continuous process (13). Table 5 Hsts the mechanical properties of roUed lead—calcium—tin alloys, compared with lead—copper and roUed lead—antimony (6 wt %) alloys. 

Lead—copper alloys are specified because of superior mechanical properties, creep resistance, corrosion resistance, and high temperature stabiUty compared to pure lead. The mechanical properties of lead—copper alloys are compared to pure lead, and to lead—antimony and lead—calcium alloys in Tables 4 and 5. 

Tia is also used as an ahoyiag element ia lead—antimony alloys to improve fluidity and to prevent drossiag, ia lead—calcium alloys to improve mechanical properties and enhance electrochemical performance, ia lead—arsenic alloys to maintain a stable composition, and as an additive to low melting alloys. 

Other early match-like devices were based on the property of various combustible substances mixed with potassium chlorate to ignite when moistened with strong acid. More important was the property of chlorates to form mixtures with combustibles of low ignition point which were ignited by friction (John Walker, 1827). However, such matches containing essentially potassium chlorate, antimony sulfide, and later sulfur (lucifers), mbbed within a fold of glass powder-coated paper, were hard to initiate and unreHable. 

Solders are alloys that have melting temperatures below 300°C, formed from elements such as tin, lead, antimony, bismuth, and cadmium. Tin—lead solders are commonly used for electronic appHcations, showing traces of other elements that can tailor the solder properties for specific appHcations. 

Solders. In spite of the wide use and development of solders for millennia, as of the mid-1990s most principal solders are lead- or tin-based alloys to which a small amount of silver, zinc, antimony, bismuth, and indium or a combination thereof are added. The principal criterion for choosing a certain solder is its melting characteristics, ie, soHdus and Hquidus temperatures and the temperature spread or pasty range between them. Other criteria are mechanical properties such as strength and creep resistance, physical properties such as electrical and thermal conductivity, and corrosion resistance. 

Other important uses of stannic oxide are as a putty powder for polishing marble, granite, glass, and plastic lenses and as a catalyst. The most widely used heterogeneous tin catalysts are those based on binary oxide systems with stannic oxide for use in organic oxidation reactions. The tin—antimony oxide system is particularly selective in the oxidation and ammoxidation of propylene to acrolein, acryHc acid, and acrylonitrile. Research has been conducted for many years on the catalytic properties of stannic oxide and its effectiveness in catalyzing the oxidation of carbon monoxide at below 150°C has been described (25). 

Antimony may be added to copper-base alloys such as naval brass. Admiralty Metal, and leaded Muntz metal in amounts of 0.02—0.10% to prevent dezincification. Additions of antimony to ductile iron in an amount of 50 ppm, preferably with some cerium, can make the graphite fliUy nodular to the center of thick castings and when added to gray cast iron in the amount of 0.05%, antimony acts as a powerflil carbide stabilizer with an improvement in both the wear resistance and thermal cycling properties (26) (see Carbides). 

Antimony is also used as a dopant in n-ty e semiconductors. It is a common additive in dopants for siHcon crystals with impurities, to alter the electrical conductivity. Interesting semiconductor properties have been reported for cadmium antimonide [12050-27-0] CdSb, and zinc antimonide [12039-35-9] ZnSb. The latter has good thermoelectric properties. Antimony with a purity as low as 99.9+% is an important alloying ingredient in the bismuth teUuride [1304-82-17, Bi Te, class of alloys which are used for thermoelectric cooling. 

---