Silicon silver halides

These incorporate membranes fabricated from insoluble crystalline materials. They can be in the form of a single crystal, a compressed disc of micro-crystalline material or an agglomerate of micro-crystals embedded in a silicone rubber or paraffin matrix which is moulded in the form of a thin disc. The materials used are highly insoluble salts such as lanthanum fluoride, barium sulphate, silver halides and metal sulphides. These types of membrane show a selective and Nemstian response to solutions containing either the cation or the anion of the salt used. Factors to be considered in the fabrication of a suitable membrane include solubility, mechanical strength, conductivity and resistance to abrasion or corrosion. 

In practice, three types of membrane based on silver halides are used. The oldest type is based on silver halide precipitate in a matrix of silicone rubber. 

Silicones, 5,113-114,135-136,261 Silk, 33-34,47, 61, 66,171 Silly Putty, 125-126,262 Silver Spencer 129 Silver halide, 122 Single-site catalysts, 106-107 Smart materials, 206-209, 218 for food packaging, 206-207 for military applications, 208 sensors for, 207,208 shape-memory polymers, 207-208 Society of Automotive Engineers (SAE), 121 Sodium acrylate, 122 ... 

Many other materials were studied as matrix materials for diffuse reflectance spectroscopy. Beside the previously noted alkali halides, other examples are silver halides, diamond, germanium, silicon, and chalco-genide glass, preferably of small particle diameters. For an extensive survey on different matrices, see Ref. °l... 

The well-known demonstrations by metallurgists that heterogeneous nucleation in metals and alloys (e.g., nucleation of pearlite) frequently occurs at dislocations (67, 68), were the precursors of the remarkable experiments of Mitchell aZ. (69-75) who decorated dislocations in transparent crystals of silver halides by exposure to light. The photo-lytic silver was precipitated along dislocations which were thereby rendered visible in the optical microscope. An extension of this technique was effected by Dash (76-80), who succeeded in decorating dislocations in opaque silicon by preferential precipitation of copper which could be detected under infrared illumination. Dash strikingly demonstrated... 

Membrane (Silicone rubber with silver halide)... 

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