41 research outputs found
Clean synthesis of biolubricant range esters using novel liquid lipase enzyme in solvent free medium
PERFORMANCE OF LOOFA-IMMOBILIZED Rhizopus oryzae IN THE ENZYMATIC PRODUCTION OF BIODIESEL WITH USE OF OLEIC ACID IN n-HEXANE MEDIUM
Structural, dielectric and impedance spectroscopy studies of (Na0.5Bi0.5)(Zr0.025Ti0.975)O3 ceramic
cited By 0International audienceStructural, vibrational, dielectric and electrical properties of (Na0.5Bi0.5)(Zr0.025Ti0.975)O3 ceramic synthesized by the solid-state reaction technique have been carried out. The X-ray diffraction analysis was indicated as a pure perovskite phase in the rhombohedral structure. The modes of rhombohedral vibrations were appeared in the experimental Raman spectrum at room temperature. The dielectric and electrical properties of the material were investigated by impedance spectroscopy analysis for a broad range of temperatures (50–560 °C) and frequency domain of 102−106 Hz. The dielectric measurement exhibit two phase transitions: a ferro-antiferroelectric transition followed by an antiferro-paraelectric transition at higher temperatures. Complex impedance analysis was carried out in order to distinct the contribution of the grains and the grain boundaries to the total electrical conduction. The Nyquist plot was proved to be a non-Debye relaxation mechanism. The combined spectroscopic plots of the imaginary part of electric impedance and modulus confirmed the non-Debye type behavior. The frequency dependent ac conductivity obeys the double power law behavior and shows three types of conduction process. The significant decrease of dc conductivity spectrum followed the Arrhenius relationship. The values of calculated activation energy of the compound implied that the electrical conduction is mostly due the high oxygen mobility. © 2017, Springer Science+Business Media, LLC
