Dielectrical properties and conduction mechanism of quinoline Schiff base and its complexes

摘要

The synthesized Schiff base ligand 8-hydroxyquinoline-7-formylidene-4-amino-1-phenyl-2,3-dimethylpyrazolin-5-one (SQL) and its Cu(II), VO(IV) and UO2(II) complexes are characterized by various physicochemical techniques. The thermal properties, dielectric properties, alternating current conductivity (sigma (ac)) and conduction mechanism of SQL and its complexes (1-6) are investigated in the frequency range of 0.1-100 kHz and temperature range 298-583 K. The temperature and frequency dependence of the real and the imaginary part of the dielectric constant are studied. The values of the thermal activation energy of conduction mechanism for SQL and its complexes under investigation are calculated at different test frequencies, and found to be in the range 0.0023-0.0798 eV for Delta E (1) and 0.0897-1.296 eV for Delta E (2). The ac conductivity, sigma (ac), is related to the frequency as sigma (ac) alpha omega (S) where the behavior of the exponent S with temperature determines the operating conduction mechanism. The correlated barrier hopping model is found to be the dominant conduction mechanism for SQL and its complexes (1) and (3-5), and the values of the maximum barrier height (W (m)) are calculated for SQL and its complexes (1) and (3-5). The quantum-mechanical tunneling is the dominant conduction mechanism for complexes (2) and (6).