Dielectric, ferroelectric and non-linear optical behavior of crystalline erbium tartrate dihydrate

The dielectric, ferroelectric and non-linear optical behavior of erbium tartrate dihydrate crystals is studied. The dielectric constant has been measured as a function of temperature and frequency. The crystals of erbium tartrate dihydrate show an anomalous dielectric behavior as a function of temperature: the dielectric constant increases with temperature, attains a peak around 235 °C and then decreases as the temperature goes beyond 235 °C. The dielectric anomaly at 235 °C is suggested to be due to ferroelectric phase transition brought about in the material. The experiment on polarization versus electric field shows a hysteresis loop thereby establishing the ferroelectric nature of erbium tartrate dihydrate. The results of thermal study show that the material is thermally stable up to a temperature of about 240 °C. The non-linear optical study shows that erbium tartrate dihydrate has second harmonic generation efficiency comparable to that of potassium dihydrogen phosphate (KDP).