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Dedensification (up to 10% of the theoretical density inweakening of the electrical properties. 20 This has been previously demonstrated on hot-pressed BaTiO 3 samples during some instances) occurs at temperatures of .1320؇C during the sintering of commercial undoped BaTiO 3 powders. The annealing treatments. 21 The purpose of this paper is to clarify the principles of expansion of the rigid, interconnected network of large, rounded grains that grow by the Ostwald ripening effect dedensification processes during the sintering of undoped BaTiO 3 . The occurrence (or absence) of a dedensification step, as can explain the dedensification that is observed. The isotropic anomalous grain growth results from the appearance well as its magnitude and onset temperature, are discussed and correlated with anomalous grain growth, the grain-boundary of a liquid phase at }1320؇C and induces tensile stresses on the residual porous fine-grained matrix. No dedensification liquid phase, and the sintering pressure. A phenomenological was observed at temperatures of ,1320؇C, despite anisoexplanation involving expansion of the large grain skeleton will tropic anomalous grain growth.be proposed.

A new scheme for coding optical signals using the polarization of light is described. The coding response is shown to be linear and invariant. As a consequence of the vectorial nature of the electromagnetic waves, this response takes a sinusoidal shape, which limits the number of channels to three. An application to fiber optics transmissions is presented; an experimental 50-m link is described. The performance and loss of the system are discussed as well as the influence of specific factors, such as the coherence length of the source and the random mode-coupling. As a conclusion, the compatibility of this new multiplexing principle with other multiplexing methods is examined.

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