Green Synthesis of Ba_(1-x)Sr_xTiO_3 ceramic nanopowders by sol-gel combustion method using lemon juice as a fuel: Tailoring of Microstructure, ferroelectric, dielectric and electrical properties

摘要

This article represents a simple, economic and low-temperature green combustion synthesis of Ba1-xSrxTiO3 (BST) ceramic nanopowders for composition x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 with lemon juice as a firing agent. The fabricated nanopowders were characterized by TGA/DSC, XRD, FTIR, FESEM, TEM etc. analytical techniques. XRD analysis reveals the formation of single-phasic tetragonal perovskite structure with no impurity phases for x = 0.0 to 0.2 samples. However, cubic phase was appeared for x = 0.4 to 1.0 samples. FTIR spectroscopic study evidenced the formation of perovskite structure by demonstrating a noticeable band in between 400 and 750 cm(-1). The Scherrer and Williamson-Hall (W-H) analysis was utilized to evaluate the crystallite size. TEM study showed that, spherical shaped and uniform nanocrystalline powders (23-28 nm) were fruitfully synthesized. The saturation electric polarization (Ps), remanence polarization (Pr) and coercive field (E-c) decreases with increase in Sr2+ content expected to be dependent on the creation of oxygen vacancies and occurrence of cubic polymorphs by doping of Sr2+ ions. The ideal ferroelectric characteristics were obtained Ps = 5.6661 mu C/cm(2) and Ec = 2.1242 kV for pristine BaTiO3 sample. Dielectric constant (epsilon') was obtained at room temperature as a function of frequency, which shows exponential decay with the increase of frequency. The Maxwell-Wagner polarization and dipole polarization were existing in the Sr2+-substituted BaTiO3 nanopowders and were responsible for the obtained dielectric properties. The variation of DC-electrical resistivity (log.) versus temperature (300 K-833 K) was observed to be decreased with increasing temperature and Sr2+ substitution; demonstrating that an electrical energy transfer was a thermally stimulated procedure. The Sr2+-substitution has brought an overall enhancement in dielectric and electrical properties. However, the ferroelectric characteristics are weakened, which is primarily attributed to a considerable variation in the micro-structure of the solid.