Phases Coexistence of Hydrogen-Bonded Mixed Ferroelectric and Antiferroelectric Crystals

Abstract

The problem proton-glass and ferroelectric phases coexistence in Rb_1−x (NH₄) _x H₂AsO₄ (RADA) and K_1−x (NH₄) _x H₂PO₄ (KADP) crystals based on dielectric studies up to temperature 0.3 K is presented. The measurements were performed in the helium-3 cryostat in the temperature range from 300 K to 0.3 K. Glass behavior for the RADA is present even for a small concentration x = 0.01, whereas for the KADP the proton glass occurs for a concentration x > 0.05. The partial phase diagrams of RADP and KADP as a function of fractional ammonium concentration x and temperature T are presented.

Keywords:

• Ferroelectric
• proton glass
• low temperature
• coexistence