Ageing process halides

Figure 1 Comparison of the spectral power distributions of a metal halide lamp during its aging process. Source Courtesy of Atlas Electric Devices, Inc.

The question of trace ionic contaminants is often overlooked. There is no doubt, however, that trace ions initially present in the polymer or subsequently introduced during the manufacturing process can wreak havoc with the device as well as with device-mounted components as the device ages and the ions migrate. Thus, not only can Na ions migrate to and destroy an FET by lowering the threshold resistance in the gate, halide ions can attack some metals, which may lead to a loss of interfacial adhesion and will certainly lead to a loss of conduction. 

The present article discusses the processes and materials used in photography, with an emphasis on the fundamental mechanisms, but does not describe the corresponding hardware (cameras, etc.), except where this is necessary to understand the process. The creative aspects of photography are also not discussed. While silver halide materials are still important, much more attention must now be given to newer technologies that have come of age at the start of a new century. 

A two-stage, countercurrent molten-salt extraction process is used to extract Am from many kilograms of aged plutonium metal in which Am has grown-in by beta decay of Pu. The purification scheme, based partly on molten-halide/molten-metal studies at the Los Alamos Scientific Laboratory and Argonne National Laboratory, ronoves about 90% of the americium from plutonium metal, typically containing 200 2000 ppm Am [16]. 

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