Ferroelectric-Paraelectric Phase Transition in Triglycine Sulphate via Piezoresponse Force Microscopy

Abstract

Triglycine sulphate (TGS) is a widely studied ferroelectric material due to its high pyroelectric coefficients and pure 2nd order phase transition of the order-disorder type. In this work, we report local piezoelectric properties and domain evolution in TGS via piezoresponse force microscopy (PFM) where the ferroelectric-paraelectric phase transition and its domain structure are visualized in a single image while slowly heating the crystal during scanning. Thus, the y-coordinate of the scan represents the temperature and serves as a temperature “lens” to zoom in peculiarities of the domain evolution and paraelectric-ferroelectric phase boundary. Strong shift of the Curie point and broad peak of the second harmonic PFM signal are rationalized in terms of the stabilization of ferroelectric phase at the surface and large contribution of the dielectric constant to the local electromechanical measurements.

Keywords:

• TGS
• piezoresponse force microscopy
• surface phase transition
• domain structure

Acknowledgments

This work was carried out in the frame of Ciência-2007 (UMINHO-CF-06) and Ciência-2008 programs of the Fundação para a Ciência e a Tecnologia (FCT) of Portugal. MW acknowledges the support of a research fellowship from the Polish Ministry of Science and Higher Education, grant No. 657/MOB/2011/0. DK was supported by the Federal Program “Research and Development in priority development areas of scientific and technological complex of Russia in 2007–2013.”