Ferroelectric Thin Films of Betaine Phosphite, Glycine Phosphite and of Their Deuterated Analogs

Abstract

Results of investigation of structural and dielectric properties of thin films of betaine phosphite, glycine phosphite and of their deuterated analogs are presented. The films were obtained by the evaporation method on different substrates. The ferroelectric phase transition is followed by a strong dielectric anomaly of film structures which depend on the substrate type (piezoelectric or non-piezoelectric). A strong dielectric non-linearity was observed near the phase transition in deuterated betaine phosphite films. In the films with a high deuteration degree the substitution of deuterium by hydrogen ions on the surface and interdiffusion of these ions inside the film was analyzed on the basis of dielectric measurements. Specific features of dielectric hysteresis loops for deuterated betaine phosphite and glycine phosphite film structures are discussed.

Keywords:

• Amino-acid ferroelectrics
• thin films
• isotope diffusion
• polarization switching, phase transitions, dielectric properties

Acknowlegments

The authors thank Dr. G. A. Pankova for preparation of DBPI and DGPI single crystals and N. V. Zaitseva for X-ray analysis.