AC conductivity and dielectric response of bulk vanadyl 2,3-naphthalocyanine.

The ac conductivity and dielectric response of bulk vanadyl 2,3-naphthalocyanine (VONPc) were investigated from 1 Hz to 106 Hz, at temperatures range from 288 K to 403 K. Thermal stability of the material was studied using thermogravimetric analysis (TGA). The structure phase was investigated using X-ray diffraction (XRD). The total conductivity was found to follow the universal power low σ(ω,T) = σ dc + Aωs. A temperature dependence and values greater than unity (super linear behavior) of the exponent factor s were found. Various types of activation energies were calculated and discussed. The calculated values of activation energies were found to be 0.27 eV, 0.23 eV and 0.21 eV for bulk conductivity (E b), dc conductivity (E dc) and relaxation process (E τ), respectively. The best conduction mechanism model that fit the observed exponent factors' values and behavior is the jump relaxation model as described by Funke. The real and the imaginary parts of the dielectric constant was observed to decrease as the frequency increases. The recorded value of the dielectric constant at high frequency is 3.3. • Ac conductivity and dielectric response of bulk vanadyl 2,3-naphthalocyanine (VONPc) were investigated using impedance spectroscopy technique. • Very good thermal stability up to 500 ᵒC was found. • Bulk conductivity, dc conductivity and the relaxation process activation energies were calculated. • Super linear frequency (s >1) and a temperature dependent of the frequency exponent factor. • The jump relaxation model as proposed by Funke was used to explain the conduction mechanism inside the material. [ABSTRACT FROM AUTHOR]