STUDI MENGENAI STRUKTUR DAN STUDY OF THE STRUCTURE AND DIELECTRIC PROPERTIES OF Pb1-XSrXTiO3 SOLID SOLUTION FOR ITS USE AS NOVEL PIEZOELECTRIC MATERIAL

• Main Author: Agustina, Elsye
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/34914
• Institution: Institut Teknologi Bandung

Titanate compounds have attracted much attention because they often display ferroelectric behavior. Among them, PbTiO3 (PTO) is particularly interesting because of its large ferroelectric polarization and its large piezoelectric response when it exists in solid solution with PbZrO3. This large electromechanical response is due to the existence, for a particular composition PbZr0.52Ti0.48O3, of a phase transition known as the Morphotropic Phase Boundary (MPB). In the search for new, lighter, and less toxic piezoelectric materials, it is important to learn if these highly piezoelectric phase boundaries can be created in other systems and by other means. One of the ideas is to create MPB’s in thin films using epitaxial strain. To try this possibility we propose to investigate Pb1- xSrxTiO3 (PSTO), which is a solid solution of PbTiO3 (PTO) and SrTiO3 (STO). This material has a Curie temperature and lattice constants that can be changed depending on the compositions of Pb and Sr. At Pb-rich compositions, the crystal structure will become tetragonal and at Sr-rich composition will be cubic. This is due to the fact that PTO has a tetragonal structure at room temperature and is ferroelectric up to its Currie Temperature of 765 K, while STO has a cubic structure at room temperature. Apart from this difference, the similarity in the structure of these two titanate perovskites allows Vegard’s law to be fulfilled in the whole composition range. This adjustable character makes PSTO thin films ideal to tune the size of the unit cell and, therefore, the amount of strain (mismatch between the unit cells of the film and the substrate) on a particular substrate. In this work, we focused on the bulk properties of the Pb1-xSrxTiO3 solid solution. PSTO pellets were made by solid state reaction using conventional ceramic methods for various compositions. X-ray diffraction confirms the evolution of the peak from cubic structure at x=1 to tetragonal at x=0. Dielectric measurement was performed on the frequency range from 100 Hz to 1 MHz starting from room temperature to 773 K in order to investigate the ferroelectric- paraelectric transition temperatures as a function of composition. The transition temperature is shown to be mask by signatures of grain boundary and interfacial conductivity. In order to extract the intrinsic dipolar responses, the dielectric constant data were analyzed with the so-called Cole-Cole plots. The 80% lead composition sample is then used as the target for thin film with SrTiO3 substrate. The thin film formed is characterized by thin film XRD, AFM, and PFM. The hysteresis loop occurred but the strain given is unsuccessful because the surface strain breaks into domain.