Silver amorphous materials

The first chemical work on calabash curare was carried out in 1897 by Boehm (8), who isolated a highly active amorphous material which was named curarine. This was soluble in water and insoluble in ether, so it is probable that Boehm was handling a mixture of crude quaternary alkaloids. Much later (1935), King described (9) the preparation of an equally active amorphous quaternary iodide from the bark of S. toxifera. However, the first isolation of well-characterized crystalline alkaloids was achieved by H. Wieland and his school (10-13). Calabash curares were extracted with methanol, and the water-soluble quaternary alkaloids in the extract were precipitated as the reineckate salts this mixture was then fractionated by adsorption chromatography on alumina. The various reineckate fractions so obtained were converted into the corresponding chlorides by successive treatment with equivalent quantities of silver sulfate and barium chloride some of the quaternary alkaloids then crystallized as the chlorides or as the picrates. C-Curarine1... 

Silver fulminate is considered as an extremely dangerous primary explosive to handle due to its high sensitivity, particularly to electric discharge and friction. It is more sensitive than MF with respect to both of these initiation stimuli. The sensitivity to electric discharge is extreme, particularly when it is dry [92]. The sensitivity of silver fulminate depends on its crystal form the amorphous form is less sensitive to impact than the crystalline form. However, since it is practically impossible to produce purely amorphous material without any crystals the whole mass might be nearly as sensitive as the crystalline form itself [29]. Taylor and Buxton published preparation of SF in form of fine crystals with an impact sensitivity significantly lower than MF (no explosion from 32.7 cm for 1/2 kg hammer vs. only 12.7 cm for MF) approaching values typical for lead azide [93]. Comparison of impact sensitivity of SF with other common primary explosives is shown in Fig. 2.15. 

The clear solution, obtained by centrifuging a solution of the oxide in aqueous ammonia which had been treated with silver nitrate until precipitation started, exploded on two occasions after 10-14 days storage in closed bottles in the dark. This was ascribed to slow precipitation of amorphous silver imide, which is very explosive even when wet [1], When silver oxide is dissolved in ammonia solution, an extremely explosive precipitate (probably Ag3N4) will separate. The explosive behaviour is completely inhibited by presence of colloids or ammonium salts (acetate, carbonate, citrate or oxalate). Substitution of methylamine for ammonia does not give explosive materials [2],... 

New approaches to the synthesis of SVO cathode material have been reported. In 1995, Takeuchi and Thiebolt patented a new preparation for SVO cathodes prepared via addition of elemental silver to vanadium compounds present in an anhydrous mixture. Oxygen-deficient SVO compounds were found, as well as compounds designed to provide a desired shape in the electrical discharge curve of the cell [59], Following this work in 1996, Takeuchi and Thiebolt patented several methods for the preparation of amorphous SVO prepared by chemical addition reaction at temperatures high enough to melt the mixture, coupled with rapid cooling... 

Impure (amorphous) boron is a brown powder, but the pure element forms shiny, silver-grey crystals. Properties including its high melting point and low electrical conductivity make B an important refractory material (see Section... 

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