The ferroelectric (1-x)[Pb(Mg1/3Nb2/3)O3]-xPbTiO3 (PMN-PT) solid solutions prepared with suitable x and synthesis techniques is technologically important for fabrication of some solid state devices such as piezoelectric transducer, actuator, FERAM etc. PMN-PT (in ceramics, thin films or single crystal forms) can be prepared with high piezoelectric coefficients, useful for devices, for example, high dielectric constant and low dielectric loss etc. It is well known that the crystallite/particle size plays an important role in tailoring ferroelectrics properties. In such materials a decrease in particle size causes a reduction in the ferroelectric distortion of the lattice and makes the diffuse ferroelectric phase transition. In some cases, typical antiferroelectric materials become ferroelectrics due to small particle size, particularly in thin films. Also, the variation of size led to an increase in the coercive field (Ec), and a decrease in the remanent polarization (Pr). For that reason, it is believed that ferroelectricity can be suppressed by fabrication of fine particles and very thin films. However, recent experiments identified ferroelectric ground states in Pb(Zr,Ti)O3 (PZT) films with thicknesses ranging from 80 to 4 nm. A stable ferroelectric phase was also observed for PbTiO3 with thicknesses down to 3 unit cells (1.2 nanometers). Though some work has already been reported in the recent past, detailed and systematic studies on ultrathin films remain an attractive/fascinating subject to study the size effects of ferroelectric. The absences of similar studies on ferroelectrics with high piezoelectric response such as PMN-PT system justify the present research project. In view of the above importance and discussion, we have mainly planned to study the structural, dielectric and electrical properties of PMN-PT ferroelectrics system. The main objectives of this research project are: i) Synthesis of homogeneous and good quality fine powder to produce ferroelectric ceramics and thin films of the PMN-PT system; ii) Detailed studies of structural, microstructural and electric properties of the PMN-PT system; iii) Studies of dielectric properties of solid solution PMN-PT (ceramics and thin films) in a wide range of temperature and frequency; iv) Studies of the nature of phase transition using polarization reversal and other methods; v) Studies of the effect of an ac and dc electric field on dielectric properties of PMN-PT ceramics and thin films as a function of frequency and temperature; vi) Studies of electrical properties of the PMN-PT using a complex impedance spectroscopy technique (CIS) and vii) Studies of the size effects on ferroelectric properties of ceramics/thin films of PMN-PT.
News published in Agência FAPESP Newsletter about the scholarship: