Structural and electrical properties of LiBa2V5O15 ceramics

A polycrystalline sample of LiBa2V5O15 (LBV) was prepared by a mixed-oxide method at low temperature (560 C). Preliminary structural analysis suggests that the compound has an orthorhombic unit cell and crystal structure. Scanning electron micrographs of the compound show a densely packed grain distribution over the entire surface of the sample. Detailed studies of the dielectric properties of the compound as a function of temperature at various frequencies suggest that the compound has a dielectric anomaly at 319 C. Some electrical parameters of LBV were measured using a complex impedance spectroscopy technique in a wide range of temperature (24-500 C). The complex impedance plots show that there are two major contributions of impedance, bulk (grains) and grain boundary, and there is a non-Debye type of dielectric dispersion. The ac/dc conductivity was found to increase with increasing temperature. The activation energy of the compound was found to be 0.38 eV. This value of activation energy suggests that the conduction process is of mixed type (ionic-polaronic and space charge generated from the oxygen ion vacancies). (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)