Molybdenum arsenide

Molybdenum Arsenide, MoAs2, is formed10 by heating powdered molybdenum for 36 hours with arsenic at 570° C., the excess of arsenic then being removed by sublimation. It is a black powder of density... 

Molybdenum arsenide has not been prepared. Molybdous arsenate is formed as a grey precipitate when molybdous chloride is treated with sodium arsenate the precipitate first redissolves but afterwards becomes permanent. Molybdic arsenate, obtained in a similar manner from molybdic chloride, has been described by Berzelius, who also considered that an acid salt was produced on dissolving moly bdic hjrdrate in excess of arsenic acid, since the solution turned blue on standing. ... 

Fission products that are compatible with the uraninite crystal stmcture—the REE, yttrium, neodymium, and zirconium—were largely retained in the uraninite core, the reactor clays, minor phosphate phases, and uranium and zirconium silicate phases (Gauthier-Lafaye et ai, 1996). Lighter REE—lanthanum, cerium, and praseodymium—were partially lost from the reactor. Einally, molybdenum, technetium, mthe-nium, rhodium, and other metallic elements were retained in the metal/metal oxide inclusions and arsenide/sulfide inclusions in the core, and in the reactor clays (Hidaka et ai, 1993 Jensen and Ewing, 2001). 

MnAs MANGANESE ARSENIDE 1035 Mo02CI2 MOLYBDENUM DICHLORIDE DIOXIDE 1074... 

Magnesium arsenide Martonite Methyl bromide Methyl fluoride Methyl mercaptan Methyl sulfate Molybdenum fluoride Nickel carbonyl Nitrogen peroxide Nitrogen trifluoride Nitrosomethylurethane Oleum (fuming sulfuric acid) Oxygen difluoride Paranitro benzyl chloride... 

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. 

Classical reagents such as azomethine-H and curcu-min are frequently used in boron determination. Azomethine-H is used, for example, in boron determination in plants, geochemical materials, and soils. Curcumin is used in determination of boron as an impurity in silicon-doped galHum arsenide used in electronics and in high-purity molybdenum. The microgram per gram limit of detection (LOD) is attained when curcumin or 4-methoxy-azomethine-H (420 nm) is used. However, boron is also determined by the formation of the macrobicyclic complex Fe(Nx) (3) (BOH) (2) in the nioxime-boric acid-Fe(II) system (447 nm). 

---