Bismuth arsenides

Bismuth Arsenides.—When bismuth and arsenic are melted together there is no evidence of chemical combination. The two elements are only slightly miscible in the molten state 7 and separate completely on solidification if an open vessel is used, but according to Heike 8 they are perfectly miscible if melted in a sealed tube. Descamps 9 melted a mixture of bismuth and excess of arsenic under fused boric oxide, keeping the temperature as low as possible, and obtained a product of density 8-45 and approximate composition Bi3As4, but it is doubtful whether this was a definite compound. 

Cobalt is the thirtieth most abundant element on earth and comprises approximately 0.0025% of the earth s cmst (3). It occurs in mineral form as arsenides, sulfides, and oxides trace amounts are also found in other minerals of nickel and iron as substitute ions (4). Cobalt minerals are commonly associated with ores of nickel, iron, silver, bismuth, copper, manganese, antimony, and 2iac. Table 1 Hsts the principal cobalt minerals and some corresponding properties. A complete listing of cobalt minerals is given ia Reference 4. 

In Moroccan deposits, cobalt occurs with nickel in the forms of smaltite, skuttemdite, and safflorite. In Canadian deposits, cobalt occurs with silver and bismuth. Smaltite, cobaltite, erythrite, safflorite, linnaeite, and skuttemdite have been identified as occurring in these deposits. AustraUan deposits are associated with nickel, copper, manganese, silver, bismuth, chromium, and tungsten. In these reserves, cobalt occurs as sulfides, arsenides, and oxides. 

Arsenic and antimony are metalloids. They have been known in the pure state since ancient times because they are easily obtained from their ores (Fig. 15.3). In the elemental state, they are used primarily in the semiconductor industry and in the lead alloys used as electrodes in storage batteries. Gallium arsenide is used in lasers, including the lasers used in CD players. Metallic bismuth, with its large, weakly bonded atoms, has a low melting point and is used in alloys that serve as fire detectors in sprinkler systems the alloy melts when a fire breaks out nearby, and the sprinkler system is activated. Like ice, solid bismuth is less dense than the liquid. As a result, molten bismuth does not shrink when it solidifies in molds, and so it is used to make low-temperature castings. 

The radii in the lowest row of the table were obtained by a number of approximate considerations. For instance, if we assume the bismuth radius to bear the same ratio to the interatomic distance in elementary bismuth as in the case of arsenic and antimony, we obtain (Bi) = 1.16— 1.47 A. A similar conclusion is reached from a study of NiSb and NiBi (with the nickel arsenide structure). Although the structures of the aurous halides have not been determined, it may be pointed out that if they are assumed to be tetrahedral (B3 or Bi) the interatomic distances in the chloride, bromide, and iodide calculated from the observed densities1) are 2.52, 2.66, and 2.75 A, to be compared with 2.19, 2.66, and 2.78 A, respectively, from pur table. 

Photoanodic dissolution in the presence of air and its promotion by methyl viologen was also observed for alkaline solutions of colloidal cadmium phosphide, CdjPj and cadmium arsenide, CdjAsj Bismuth sulfide, Sb Sj, photo-dissolves in the presence of air mainly according to... 

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. 

In his Elements of the Art of Assaying Metals, Johann Andreas Cramer pointed out the close association of bismuth with arsenic and cobalt. Every ore of Bismuth, said he, as is shewn by the chemical analysis, is reduced to the State of Ore by Arsenide For this goes out of it by Sublimation. You find m the same Ore that Kind of Earth that gives an azure Colour to Glasses, of which we have already spoken in the Article of Cobalt. Whence it is evident that the Ore of Bismuth may widiout Impropriety be called Cobalt of Bismuth The more, because you will find in any ore of Bismuth the same Principles as in Cobalt, only in a different Propoition (55). This close association of bismuth and cobalt m nature made it difficult for eaily chemists to distinguish between them (56). 

Nickel is often used as matrix modifier in the determinations of arsenic and selenium. Nickel stabilizes arsenic up to about 1700 K, and selenium up to about 1500 K. This is presumably due to the formation of thermally stable nickel arsenide and nickel selenide. Nickel can also be used to stabilize bismuth, antimony, and tellurium. In addition, copper, silver, molybdenum, palladium, and platinum salts have been proposed as stabilizers for these elements. Palladium and platinum are the most suitable matrix modifiers for both inorganically and organically bound tellurium. Pretreatment temperatures up to 1320 K can be used. The effect of different matrix modifiers on the determination of antimony are shown in Figure 74. Without matrix modifiers the losses of antimony begin at 1000 K. Palladium, molybdenum, and nickel are the most suitable to stabilize antimony and with these modifiers pretreatment temperatures up to about 1600 K can be used. 

Volclay 351CER Volclay HPM-75 Volclay KWK 200 Volclay KWK Food Grade Volclay NF-BC Xtra Gel 215-114-8 Gallium arsenide 215-125-8 Boron oxide 215-127-9 Barium oxide 215-128-4 Barium peroxide 215-134-7 Bismuth oxide 215-135-2 Bismuth telluride 215-136-8 Bismuth subnitrate 215-137-3 Calcium hydroxide Calcium Hydroxide BC 802 Calcium Hydroxide HP Fluorox E... 

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