New crystallization of nano-crystals by high pressure

高压结晶的优点是将成核过程与复杂的结晶过程区分开来，并能改变溶质在常压下的溶解度。压力可以以声速扩展到系统中，这与浓度和温度完全不同，浓度和温度的速度受到扩散率和热导率的限制。我们可以有新的仪器来研究4000巴以上的溶液。在自由活塞型小瓶中可以轻松更换溶液。我们首次观察到两种铵盐在高压下的成核现象，并发现随着压力的增加，两种铵盐的溶解度会降低。这两种盐可以通过高压结晶。此外，两种铵盐在乙醇水溶液中的高压过饱和溶液中均能成核，高压结晶过程中均存在两种铵盐的介稳区。当盐在溶液中的溶解度较小时，介稳区的宽度较大。用动态光散射法测定了高压下影响晶核生长的乙醇溶液粘度。随着压力的增加，乙醇水溶液的粘度变得很大，这会限制晶核的生长。此外，还测量了高压下乙醇水溶液的电导率。我们可以开发新的具有偶极子的高压电池。在高压下，两种铵盐在乙醇水溶液中的电导率均显著降低。本计画之研究结果，为后续计画提供了一种利用成核过程在高压下高速充电的新方法。

The advantages of high pressure crystallization are to distinguish the nucleation process from complicated crystallization processes, and to change the solubility of solute at atmosphere pressure. The pressure can expand into the system at speed of sound, and that is quite different from concentration and temperature which speeds are limited by diffusivity and thermal conductivity. We could have the new apparatus to investigate the solution at more than 4000 bar. The solution can be easily changed in the free-piston type vial. We first observed the nucleation of two ammonium salts at high pressure, and found that the solubility of two ammonium salts could be decreased as pressure increased. Those two salts could be crystallized by high pressure. Moreover, two ammonium salts in aqueous ethanol solution were nucleated at supersaturated solution by high pressure, and the metastable zones for two ammonium salts were found in high pressure crystallization. The width of metastable zone was large when the solubility of salt was small in the solution. The viscosity of ethanol solution that influences the growth of crystal nuclei was also measured at high pressure by DLS method. The viscosity of aqueous ethanol solution became very large as pressure increased, and that could limit the growth of crystal nuclei. In addition, electric conductivity of aqueous ethanol solution was also measured at high pressure. We could developed new high pressure cell having dipoles. The electric conductivities of two ammonium salts in aqueous ethanol solution decreased considerably at high pressure. As a results of this project, we could have new method to charge electron in battery at high speed at high pressure by nucleation process for further project.