Accession Number : AD0671905

Title :   DEFECT STRUCTURE FERROELECTRICS (DIELECTRIC AND STRUCTURAL INVESTIGATIONS OF FERROELECTRICS POSSESSING DEFECT STRUCTURES).

Descriptive Note : Final rept. Sep 61-Sep 68,

Corporate Author : ILLINOIS UNIV URBANA DEPT OF CERAMIC ENGINEERING

Personal Author(s) : Tennery,Victor J. ; Hang,Kenneth W.

Report Date : 15 JUL 1968

Pagination or Media Count : 38

Abstract : 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<x=or<0.40 when the ratio of N:P was within the limits 1:2 to 2:1. A ferroelectric pseudomonoclinic perovskite phase was observed at 25 degrees C when 0=or<x-or<0.10 in the series studied. (Author)

Descriptors :   (*FERROELECTRIC CRYSTALS, *PHASE STUDIES), CRYSTAL STRUCTURE, SOLID SOLUTIONS, X RAY DIFFRACTION, PIEZOELECTRIC EFFECT, ENTROPY, ENTHALPY, TRANSITION TEMPERATURE, CALORIMETRY, SODIUM COMPOUNDS, POTASSIUM COMPOUNDS, STRONTIUM COMPOUNDS, CADMIUM COMPOUNDS, NIOBATES

Subject Categories : Physical Chemistry
      Crystallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE