Green Synthesis of Ba1−Sr TiO3 ceramic nanopowders by sol-gel combustion method using lemon juice as a fuel: Tailoring of Microstructure, ferroelectric, dielectric and electrical properties

Abstract

Abstract 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 (Ec) 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 μC/cm2 and Ec = 2.1242 kV for pristine BaTiO3 sample. Dielectric constant (e’) 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 ρ) 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.