Growth of high quality barium titanate crystals for neuro-computers

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BaTiO_3 is one of the best photo-refractive materials for experimental researches on the optical-neuro-computings, because it has a good figure of merit and sufficiently high response. However, because many studies for the crystal growth have not been done, it is very difficult to obtain the cry cvls on commercial basis stably. This has been a severe problem for proceeding the experimental researches on optical computing.In the present research, we investigated the growth technique of BaTiO_3 crystals of good quality, in order to get the crystals of enough quality for optical computing experiments.First, the photo-refractive effects have been reconsiderates for considering to use in the optical computing. Next, the present condition of experimental researches have been surveyed in order to clarify what kinds of qualities becomes the problems in experimental work. Third, based upon these, the crystal conditions were investigated using both an induction heating and a resistance heating growth units. As a result, we found out the one of the most impotrant factor was temperature stability. We also tried to grow thin film type BaTiO_3 crystals by the pulsed laser deposition method. In this case, we found out that the origin of impurities (in this case, particles) and could discuss how to avoid the undesirable particles. Finally, we also proposed and demonstrated a new technique for coating of BaTiO_3 crystals at room temperature which is much lower than a BaTiO_3's phase transition temperature of 120.