Dielectric nonlinear properties of pyridinium tetrafluoroborate single crystal near the ferroelectric phase transition

Pyridinium tetrafluoroborate (PyBF4) single crystals have been grown and their dielectric properties around the ferroelectric phase transition at 237.3 K were studied. The electric permittivity was measured as a function of temperature as the dc electric field ranged between 0 and 1100 kV/m. The electric permittivity was also measured at constant temperature as a function of the electric field intensity, which was changed slowly in the range 0–650 kV/m. Detailed measurements of spontaneous polarization were done by means of a Sawyer–Tower circuit and a pyroelectric method. The results of the experimental studies were analyzed in the framework of the classical dielectric state equation and the nonlinearity coefficient B was estimated. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)