Growth of high quality barium titanate crystals for neuro-computers

BaTiO_3具有良好的性能和足够高的响应，是光神经计算实验研究的最佳光折变材料之一。然而，由于对晶体生长的研究还很少，因此很难稳定地获得商业化的晶体。这已经成为进行光学计算实验研究的一个严峻问题。在本研究中，我们研究了高质量BaTiO_3晶体的生长技术，以期获得足够质量的光学计算实验晶体。首先，对光折变效应进行了重新考虑，以考虑在光学计算中应用。其次，对实验研究的现状进行了综述，以澄清实验工作中存在的问题。第三，在此基础上，利用感应加热和电阻加热生长单元研究了晶体条件。因此，我们发现温度稳定性是最重要的因素之一。我们还尝试用脉冲激光沉积法生长薄膜型BaTiO_3晶体。在这种情况下，我们发现了杂质（在这种情况下是颗粒）的来源，并可以讨论如何避免不良颗粒。最后，我们还提出并演示了一种在室温下对BaTiO_3晶体进行涂层的新技术，该技术远低于BaTiO_3的相变温度120℃。

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.