Linear and non-linear dielectric spectroscopy on ammonium doped Rochelle salt

TL;DR

This study investigates the dielectric properties of ammonium-doped Rochelle salt across various concentrations, revealing a new electrically ordered phase and providing updated insights into its complex phase diagram using advanced spectroscopy techniques.

Contribution

It offers new experimental data on the dielectric response of Rochelle salt with ammonium doping and identifies a previously unreported electrically ordered phase.

Findings

Detection of a new electrically ordered phase for 0.18<x<0.89

Detailed analysis of relaxation features in dielectric response

Qualitative modeling for x=0 and x=0.15

Abstract

In this work we present a thorough investigation of the mixed system of Rochelle salt doped with ammonium, with 0<=x<=1 for [Na(K{1-x}(NH4)x)C4H4O6 * 4H2O]. This interesting system is known to exhibit a rich phase diagram with a variety of polar and non-polar phases. However, most of the earlier investigations date back many decades and the experimental advances made since then should enable new insight into the physical nature of its phase diagram. We studied single crystals of 18 doping concentrations using linear and non-linear frequency-dependent dielectric response spectroscopy. In the low field measurements a variety of relaxation features are detected and analyzed in detail. The results for two concentrations of x=0 and x=0.15 are described qualitatively with a simple model. Possibly the most important outcome of the present work is the detection of a new electrically ordered phase for concentrations 0.18<x<0.89.