DEFECT STRUCTURE FERROELECTRICS (DIELECTRIC AND STRUCTURAL INVESTIGATIONS OF FERROELECTRICS POSSESSING DEFECT STRUCTURES).
Final rept. Sep 61-Sep 68,
ILLINOIS UNIV URBANA DEPT OF CERAMIC ENGINEERING
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Thermal and X-ray diffraction studies of the system NaxK1-xNbO3 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 Na1-xSrNCdPNbO3 where NPx2 between 0orxor0.40 when the ratio of NP was within the limits 12 to 21. A ferroelectric pseudomonoclinic perovskite phase was observed at 25 degrees C when 0orx-or0.10 in the series studied. Author
- Physical Chemistry