Coexistence of Antiferroelectric and Proton Glass States in Mixed K_0,26(NH₄)_0.74H₂PO₄ Crystal Under Restricted Geometry Conditions

Abstract

The dielectric response of K_0,26(NH₄)_0.74H₂PO₄–SiO₂ composite prepared by embedding of corresponded salts into porous SiO₂ glass with 320 nm average pore diameter has been studied at the temperature range of 10–300 K. The transition from paraelectric to antiferroelectric (AFE) phase in implanted particles is detected at T_N ≈ 45 K. Below ≈ 20 K the specific dispersion of dielectric response indicates a transition into proton glass (PG) state. It was found that the average time of dielectric relaxation follows the empirical Vogel—Fulcher law. Obtained results speak in favor of the coexistence of AFE and PG phases at low temperatures.

Keywords:

• Proton glass
• antiferroelectric
• mixed crystal
• composite
• porous glasses
• phase transition
• phase coexistence

Acknowledgments

This work was supported by Russian Foundation for Basic Research (grant no. 08-02-01089-a) and by Wroclaw University of Technology.