Comment on '[N(CH3)3H]2ZnCl4: Ferroelectric properties and characterization of phase transitions by Raman spectroscopy'

TL;DR

This paper critiques a previous study on [N(CH3)3H]2ZnCl4, highlighting inconsistencies in ferroelectric phase transition observations and emphasizing the need for further investigation into its phase behavior.

Contribution

The paper provides a critical analysis of existing claims about the ferroelectric properties and phase transition nature of the compound, questioning prior conclusions based on experimental discrepancies.

Findings

No ferroelectric hysteresis observed below 282 K

Dielectric loss significantly exceeds dielectric constant

Phase transition likely of first order, contrary to previous claims

Abstract

The authors of paper commented claim that trimethylammonium tetrachlorozincate crystal shows at 282 K the ferroelectric-paraelectric phase transition. But no ferroelectric hysteresis loop was observed below this temperature. Moreover, in the low-temperature phase the ferroelectric domain walls should exist giving dielectric relaxation in a low frequency electric field. The authors conclude that the phase transition is of the second order. This conclusion is contrary to the DSC data where the phase transition has a strong first order character. In the whole measured temperature range the dielectric loss is 100 times higher than the real part of dielectric constant.