Defect Structure Ferroelectrics (Dielectric and Structural Investigations of Ferroelectrics Possessing Defect Structures)

摘要

Thermal and X-ray diffraction studies of the system Na(x)K(1-x)NbO3 have revealed the presence of phase boundaries at approximately 82.5, 67.5 and 52.5 mole percent NaNbO3 at 25 degrees C in addition to the one previously reported very near the NaNbO3 end member. The optimum piezoelectric properties observed in this system are apparently associated with compositions near the latter boundary. Calorimetric determinations of the enthalpy and entropy changes associated with the ferroelectric-ferroelectric and ferroelectric-paraelectric transformations in the system clearly revealed the presence of the phase boundaries. No multiple cell perovskite structures were observed in the system at NaNbO3 concentrations below about 70 mole percent. Solid solution was observed in the system Na(1-x)Sr(N)Cd(P)NbO3 where N+P=x/2 between 0=or