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Cubic–tetragonal–orthorhombic phase transition sequence in 0.5PbMg 1/3 Nb 2/3 O 3 –0.5PbTiO 3 and 0.36PbMg 1/3 Nb 2/3 O 3 –0.64PbTiO 3 single crystals

2006; IOP Publishing; Volume: 18; Issue: 42 Linguagem: Inglês

10.1088/0953-8984/18/42/009

1361-648X

A. Kania, Ph. Daniel, Aneta Slodczyk,

Microwave Dielectric Ceramics Synthesis

X-ray powder diffraction, Raman scattering and dielectric studies of 0.5PbMg1/3Nb2/3O3–0.5PbTiO3 (0.5PMN–0.5PT) and 0.36PbMg1/3Nb2/3O3–0.64PbTiO3 (0.36PMN–0.64PT) single crystals were carried out over a wide temperature range. The structural investigations revealed the existence of two structural phase transitions. The first one, from the paraelectric cubic () to the ferroelectric tetragonal (P4mm) phase, occurs at 505 and 575 K for 0.5PMN–0.5PT and 0.36PMN–0.64PT, respectively. The second one, from the tetragonal to orthorhombic ferroelectric (Pmm 2) phase, is observed at 292 K for 0.5PMN–0.5PT and at 235 K for 0.36PMN–0.64PT. The Raman investigations confirmed the existence of those phase transitions. The lowest frequency mode behaves like a soft mode. The dielectric investigations showed a sharp maximum of ε'(T) at TC, characteristic for normal ferroelectrics. Some evidence of the tetragonal–orthorhombic phase transition was detected by the dielectric and pyroelectric studies of only the polarized samples.