NUCLEAR RADIATION Detector Materials This Symposium, Chaired by E
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CERAMICS FROM SOLUTIONS: sol-gel and fine powder technologies During the last thirty years, of submicron dimensions is being having well defined properties at techniques for making ceramic revealed by electron optic methods. significantly lower firing temperatures materials with well defined properties Some applications of sol-gel promises to revolutionize the ceramic have increasingly relied on soluble techniques are well advanced. industry during the coming decades. salts and metal-organic precursors to Extensive work on spherical nuclear As volume increases the cost of most meet exacting chemical purity, fuel forms was presented and the metal organics will decrease homogeneity and microstructural variety of optical coatings available dramatically. When the overall requirements. The resulting was described. A new class of cermets economics are considered, sol-gel and improvements m reactivity, was presented that can be expected to fine particle ceramic technologies in compositional control and process possess unusual electrical properties. combination with advanced heating flexibility have greatly extended our The results of a determination of the methods such as microwave will ability to make novel, utilitarian structure of vanadium pentoxide gels displace many traditional ceramic materials that are well beyond the were presented. Antistatic coatings processing methods. limits believed to exist when only made from these gels have been used naturally occurring minerals were to coat over five million square available. This symposium reviewed meters of photographic film in DON E. HARRISON these developments and it gave an France. Novel switching and display Westinghouse R&D Center indication of the advances that will be devices were also described that are RUSTUM ROY made in the near future. based on vanadium and tungsten gels. The Pennsylvania State University Sol-gel techniques permit mixing of A new gel-glass, high-level nuclear multicomponent systems on a waste form was demonstrated to molecular level that decreases successfully immobilize reprocessing diffusion distances sufficiently to waste. Principal Support lower the maturing temperature by The preparation of silicon carbide hundreds of degrees. Several speakers fibers from silanes and silizanes was Army Research Office, described how these complex described as well as the carbothermic Metallurgy and Materials Science structures are becoming understood reduction of sol-gel derived Division (P. Parrish) in terms of the specifics of the precursors to make sinterable silicon metal-organic precursor and gellation carbide powders. Supplemental Support history. The complex morphologies The ability to reproducibly make a of these structures within a structure wide range of ceramic materials Westinghouse Electric Company NUCLEAR RADIATION detector materials This symposium, chaired by E. E. Several clear developments and E.E. HALLER Haller of Lawrence Berkeley trends can be summarized: high Lawrence Berkeley Laboratory and Laboratory, and by H. W. Kraner and purity germanium has completely U. of California, Berkeley W. A. Higenbotham of Brookhaven displaced lithium-compensation of p H.W. KRANER National Laboratory, provided a type material as a means of producing Brookhaven National Laboratory forum for nine invited papers and ten large sensitive detector volumes and W.A. HIGINBOTHAM contributed papers addressing the prospects are good for the same Brookhaven National Laboratory status and problems of semiconductor application m silicon; bismuth and scintillator detector materials. germanate may also displace Invited papers reviewed the growth thallium-activated sodium iodide as Principal Support and utilization of silicon, germanium, the workhorse scintillator for many cadmium telluride and mercuric applications; mercuric iodide and Department of Energy, Office of iodide semiconducting materials and cadmium telluride continue to mature Health and Environmental sodium iodide, bismuth germanate as high-Z, room temperature Research (R. W. Wood and J. and cadmium tungstate scintillators. semiconductor materials for many Goldstein) Contributed papers discussed surface special applications, including X-ray preparation of silicon, growth of high spectrometry; and, finally, a large arc Supplemental Support purity silicon, growth of and contact light sensitive silicon photodiode has to mercuric iodide and the use of demonstrated sufficient gain to prove Canbe"a Industries silicon photodiodes to sense Nai(Tl) useful as a solid state photomultiplier EG&G ORTEC scintillators. viewing Nai(Tl) light. Harshaw Chemical Company PAGE 10, MRS BULLETIN, NOVEMBER/DECEMBER 1982 .