tailieunhanh - Influence of lithium content on the structure and ionic conductivity of perovskite La(2/3)−xLi3xTiO3 made by double mechanical alloying method

In these samples, a change of symmetry from tetragonal to orthorhombic is observed for sample with lithium content x = . Structural modifications were obtained mainly due to the cation vacancies ordering along the c-axis, which disappeared gradually when the lithium content increased. At room temperature, the maximum values of grains and grain boundaries conductivities of the La(2/3)−xLi3xTiO3 samples were found to be of ×10−3 S/cm and ×10−5 S/cm, respectively. The temperature dependence of ionic conductivity obeyed a non-Arrhenius behaviour. At temperature from 30 to 125 oC, the activation energy for grain and grain-boundary conductivity was found to be of ∼ eV and ∼ eV, respectively. | Communications in Physics, Vol. 24, No. 3S1 (2014), pp. 33-39 DOI: INFLUENCE OF LITHIUM CONTENT ON THE STRUCTURE AND IONIC CONDUCTIVITY OF PEROVSKITE La(2/3)−x Li3x TiO3 MADE BY DOUBLE MECHANICAL ALLOYING METHOD LE DINH TRONG Hanoi Pedagogical University E-mail: trongldsp2@ Received 20 June 2014 Accepted for publication 20 August 2014 Abstract. Perovskite La(2/3)−x Li3x TiO3 samples with 6 x 6 were prepared by a double mechanical alloying method. Structure and Li+ -ion conductive properties of the La(2/3)−x Li3x TiO3 samples were investigated. Most of the analyzed perovskite samples exhibit a double unit cell. In these samples, a change of symmetry from tetragonal to orthorhombic is observed for sample with lithium content x = . Structural modifications were obtained mainly due to the cation vacancies ordering along the c-axis, which disappeared gradually when the lithium content increased. At room temperature, the maximum values of grains and grain boundaries conductivities of the La(2/3)−x Li3x TiO3 samples were found to be of ×10−3 S/cm and ×10−5 S/cm, respectively. The temperature dependence of ionic conductivity obeyed a non-Arrhenius behaviour. At temperature from 30 to 125 o C, the activation energy for grain and grain-boundary conductivity was found to be of ∼ eV and ∼ eV, respectively. Keywords: double mechanical alloying; perovskite structure; lithium onic conductivity, impedance spectra. I. INTRODUCTION Recently, ionic conducting solid materials have received considerable attention due to their potential applications in all-solid-state ionic batteries, energy storage and conversion, electrochromic displays, and in environmental monitoring electrochemical sensors, etc [1]. These materials are non-toxic solid electrolytes exhibiting easy preservation and comfortable use. From many works it is seen that a family of the perovskite structure of La(2/3)−x Li3x TiO3 .