Stages in ferroelectric transition of TGS

Abstract

Ferroelectric crystal triglycine sulfate (TGS) present distinct properties, in the ferro phase, on four temperature stages: Tc-45-40-35-30 (25)°C for all measured parameters. The lower limit of the ferroelectric transition was for first time estimated to be about 24 °C down the Curie point. Crystals grown by slow solvent evaporation in para phase, were cleaved and polished plates were silver paste painted as electrodes. Alpha-A Novocontrol spectrometer was used for dielectric spectroscopy measurements (1–10⁶ Hz), crossing down-up-down the Curie point, between 65 °C and −120 °C at a pace of 0.6 °C/minute. Surprisingly, in all three runs Z2, Z3, Z5 crystal properties appear unstable on the temperature interval 45 °C-Tc. In the run Z3, the conductivity falls down two order of magnitude, 4 °C before crossing up the Curie point. The frequency coefficient N shows distinct ranges of linear temperature dependence on the interval 25–45 °C showing, in Arrhenius coordinate, the activation energies close to the values of A.C. conductivity. On the zone 45 °C-Tc, N coefficient shows also a non-Arrhenius temperature dependence. At the other end, down 25 °C towards zero Celsius, N increases rapidly from 0.2 towards 0.8, suggesting the influence of the ferro transition was closed. Literature data of some other parameters were listed, to sustain the temperature stages.

Keywords:

• TGS dielectric spectroscopy
• ferroelectric unstable stage
• conductivities
• activation energies
• limited transition

Acknowledgement

Author is really indebted to Dr. Constantin-Paul Ganea from the National Institute of Materials, Bucharest-Magurele, for data registration and for excellent collaboration. He is also grateful to candidate for Dr. degree Dan Marinel for his active collaboration in rebuilding graphics from literature, listed here.

Disclosure statement

No potential conflict of interest was reported by the author(s).