Dielectric Characteristics of Sr Sm and Zr Doped Bulk Batio3 and Optical Properties of Sr Doped Batio3 Thin Films Prepared By Pulsed Laser Deposition

Abstract

Structural, microstructural, and dielectric properties of co-doped ceramics with co-dopant at A site (Sr, Sm) and B site (Zr) in ABO3 of BaTiO3 solid solution were prepared through sol-gel and calcinated at 1473 K for 3 hours followed by sintering at 1723 K for 4 hours at atmospheric condition. The dielectric properties of the BaxSr(1-x)TiO3 pellets prepared by sol-gel method revealed that Curie temperature decreased on replacing Ba by Sr. Dielectric studies revealed higher dielectric constant and low dielectric loss for Ba0.6Sr0.4TiO3 compared to that of other two compositions. Polarization-electric field (P-E) hysteresis loop measurements of Ba0.6Sr0.4TiO3 ceramic pellet revealed that the saturated polarization and remanent polarization were found to increase steadily up to the temperature of 165 K and then decrease drastically at about 323 K as a consequence of ferroelectric to para-electric transition. newline(Ba1-xSmx) (Ti0.75Zr0.25) O3-and#948; (BSTZO) with x = 0.02, 0.04, and 0.06 mol % of ceramic compounds were prepared by solid state reaction route. Oxygen vacancy concentrations were determined by in-situ high temperature Raman spectroscopy in the temperature range of 301-773 K. (Ba0.6Sm0.4) (Ti0.75Zr0.25) O3-and#948; composition has shown higher dielectric constant (2010) and lower loss tangent with varying frequencies from 100 Hz to 20 MHz due to its lower oxygen vacancy concentration and higher particle size compared to other compositions. newlineThe thesis also deals with Ba0.6Sr0.4TiO3 thin films deposited by PLD method on Si (100) and quartz substrates at different substrate temperature and oxygen partial pressure. X-ray diffraction results revealed that the thin films were amorphous when the substrate temperature was up to 673 K and newlinevii newlinethe crystallinity was found to be improved at the substrate temperature of 873 K. There was an increase in the lattice parameter value from 3.97 to 4.01 Å with an increase in the oxygen partial pressure. UV-visible spectroscopy showed that the band gap of the BST films deposited on quartz