氷エレクトレットの作製と電荷量

Abstract

Ferroelectric ice, ice XI, existing at the cryogenic temperature of 1 atm is a very interesting material because of its high electrical stability at low temperature and its low environmental impact. However, the ice XI formation process is very difficult. The dielectric properties of ice are governed by the behavior of the hydrogen ions, protons. Protons in ice can hop along lattice defects at a relatively high temperature, e.g., 253 K. At a cryogenic temperature such as 77 K, proton movement in ice is difficult. To obtain polarized ice, we applied DC voltage to normal ice, ice Ih, at 253 K and cool it down to 77 K with voltage application. In this process, protons in ice hop to the cathode side at 253 K and stop moving at 77 K, therefore polarization fixed there. The polarized ice is called "ice electret." The electrical properties and structure of ice electret have not yet been clarified. We produced ice electret using the aforementioned method and observed its depolarization current. We changed the application time and magnitude of voltage in during the formation process and measured the charged stored in the ice electrets produced. The results show that the stored charge in ice electret increases with application time and amplitude of voltage.