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Continuity in Phase Transition Behavior between Normal and Diffuse Phase Transitions in Complex Perovskite Compounds

1992; Institute of Physics; Volume: 31; Issue: 9S Linguagem: Inglês

10.1143/jjap.31.3241

1347-4065

Makoto Kuwabara, Seiji Takahashi, Koji Goda, Kenji Oshima Kenji Oshima, Koichiro Watanabe Koichiro Watanabe,

Acoustic Wave Resonator Technologies

The phase transition behavior in the systems of (1- x )Pb(Mg 1/3 Nb 2/3 )O 3 - x PbTiO 3 (PMN-PT) and 0.99Pb 1- y La 2 y /3 TiO 3 -0.01MnO 2 (PLT) relaxor ferroelectrics has been investigated to explore the nature of diffused phase transitions (DPT) in these materials. All the dielectric constant (ε)-temperature ( T ) characteristics for these materials above the Curie point have been found to be described by the equation (1/ε-1/ε m ) 1/ n =( T - T m )/ C ′ , where ε m is the maximum dielectric constant of a material, T m is the temperature giving ε m , and n and C ′ are constants changing with composition. In the system PMN-PT, the value of n was found to change continuously from 1.0 for PT to 2.0 for PMN without any irregularity. The value of n for the materials of the system PLT also shows a similar variation with La content, and moreover, two C ′ versus T m plots obtained for the two systems PMN-PT and PLT show substantially the same behavior. The nature of DPT is considered to be closely connected with compositional and structural variations, which determine the spatial size and morphology of ferroelectric domains below the Curie point.