Structural evolution and electrical properties of the biphasic compound α-Al2O3:MgAl2O4

Magnesium ion doped alpha-Al2O3 (Mg:Al2O3) with different Mg concentrations (0,1, 3,5 and 10 mol%) was prepared through chemical co-precipitation method. Structural analysis by XRD and Raman spectroscopy revealed the dominant alpha-Al2O3 phase along with spine! MgAl2O4 as secondary phase. Impedance analysis signalized that the grains are dominating in the electrical conduction process. The electrical relaxation process was temperature dependent and non-Debye type. Electrical conductivity of Mg:Al2O3 increased with temperature as well as with Mg content. The 10 mol% showed increased conductivity from 1.1 to 4.1 mu S/cm at 475 degrees C. It followed the Arrhenius behavior and the mechanism for conduction was proposed by a model where conduction is taking place via grain and grain boundary ionic path. Universal scaling behavior electrical modulus was achieved at a given measuring temperature showing that the dynamic process occurring at different frequencies exhibit the same thermal activation process and independent of Mg ion concentrations. (C) 2017 Elsevier Ltd. All rights reserved.