22 October 2003 Phase transitions in PbTiO3 microcrystals of different size
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Abstract
PbTiO3 crystal is a model ferroelectric material exhibiting perovskite-type structure, high Curie temperature (Tc = 765 K), large spontaneous polarization (Ps=0.42 Cm-2) and electrical conductivity at TcTc =0.1 Ω-1m-1). A method of preparation of PbTiO3 micro-crystals (size 1 - 50 μm) exhibiting isometric shapes and a method of segregating microcrystals into fractions within a narrow size range has been developed. The present work gives results of investigations on kinetics of the phase transition in micro-crystals exhibiting different dimensions. It has been found that P4mmPm3m phase transition occurs in microcrystals in the presence of a single plane interface of {023}-type. During cooling of micro-crystals, the phase plane is followed by formation of the domain structure, which is a superposition of 180° dielectric domains and 90° domains (i.e. structural twins). The temperature hysteresis of position of the phase boundary is ΔTPT ≈ 7K. Such a situation occurs in case of micro-crystals with dimensions larger than critical size (rcr ≈ 20 μm). In case of r < rcr the plane phase boundary is followed by formation of 180° domains only; the structure of 90° do not longer form. The thermal hysteresis also occurs but its value is two times larger (ΔTPT ≈ 14 - 17 K).
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Zygmunt Surowiak, Evgeni G. Fesenko, Vladimir G. Gavrilachenko, Vladimir D. Komarov, Dionizy Czekaj, "Phase transitions in PbTiO3 microcrystals of different size", Proc. SPIE 5136, Solid State Crystals 2002: Crystalline Materials for Optoelectronics, (22 October 2003); doi: 10.1117/12.518744; https://doi.org/10.1117/12.518744
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