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Second-order optical properties of thermally poled arsenicgermanium sulfide glasses have been investigated. Parallel studies of glass structure changes upon poling and/or visible cw-laser irradiation and complete SHG quantitative analysis have been performed. Key parameters and poling mechanisms influencing largely SHG stability and efficiency have been pointed out.

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We report on the compaction of anhydrous BaCl 2 powders under severe plastic deformation and the conversion of their native orthorhombic cotunnite crystalline structure into a fine-grained cubic fluorite structure. This conversion, supported by x-ray diffraction and transmission electron microscopy data, and which enables the production of highly dense ceramics of BaCl 2 , occurs 500 o C below the known phase transition temperature of 925 o C for this material at 1 atm. We discuss this phase change in the context of a stress-induced polymorphic transformation and its implication on the fabrication of transparent ceramics for scintillator applications.