Síntese e Caracterização Elétrica do Composto Cerâmico Bifásico Trititanato de Sódio e Hexatitanato de Sódio

Abstract

Systems based on sodium ion and titanium oxide have proven to be of great potential for such applications: solid state electrolytes and electrodes, sensors and photocatalysis. Materials with high ionic conductivity have wide utility as a battery element. However, basic physical properties are still discussed. The bifasic ceramic system composed of Na2Ti3O7 and Na2Ti6O13 was produced from a solution of sodium hydroxide and titanium isopropoxide dissolved in isopropyl alcohol, synthesized by sonochemical method, thermally treated and sintered. The identification of lattice parameters, phases and crystallite size of NTO (system formed by sodium hexatitanate + sodium trititanate) - without heat treatment and NTO - Heat treated systems were carried out by rietveld refining of the samples diffractograms. The raman spectrus of NTO - Pure and NTO - Treated systems were fitted with lorentzian curves which enabled the identification of the experimentally activated vibrational modes. Two sintering temperatures were tested on the disk-shaped sample, 900°C and 1000°C. The superficial region and fracture morphologies were analyzed in order to obtain both the external and internal region micrographs. The characterization of electrical properties, the conduction mechanism study and the identification of electric charge carries of any system are of great value when we are looking for system with potential for application as a battery element. In this present work, electrical characterization was performed by electrical impedance spectroscopy. Impedance measurements with frequency and temperature variation were performed. Detailed analysis of the electrical response in different formalities were performed. The identifications of the maximum frequency values in the diagram Z''xlnf, maximum values of electrical module in the diagram M''xlnf and maximum values of σDC through curve fitting with Jonscher equation in the diagram σ'xlnf enabled the system activation energy identification.The energy activation values were calculated by tree differences formalizes, and are respectively Ea = 0,298 ± 0,02eV$, Ea = 0,178 ± 0,004eV, Ea = 0,357 ± 0,01eV.