Microstructural evolution of 0.75PMN-0.25PT ferroelectrics synthesized by hydroxide co-precipitation method and their dielectric properties

摘要

Abstract 0.75PMN-0.25PT, a relaxor ferroelectric composition has been synthesized by hydroxide co-precipitation method. In order to study the evolution of microstructure the composition under investigation has been sintered in the temperature range of 1000-1280 ℃. Effects of sintering temperature on microstructural properties and hence on crystalline phase, density, dielectric, ferroelectric and piezoelectric properties of the 0.75PMN-0.25PT ceramics have been systematically investigated. It is observed that the 0.75PMN-0.25PT ceramics sintered at 1250 ℃ gives highest values of dielectric constant ε_(max) and maximum polarization Pmax, while highest observed value of piezoelectric coefficient d33 is 480 pC/N at sintering temperature Ts equal to 1280 ℃ which are associated with the compact microstructure of the samples. In addition, the nature of phase transition as depicted from temperature dependent dielectric behavior has been analyzed in terms of diffusivity parameter 8 and degree of diffuseness y. The room temperature Raman spectroscopy technique has been used to identify the vibration modes in the PMN-PT. Raman spectra recorded as a function of temperature is used to understand the ferroelectric phase transition of the sample.