Effects of crystallization kinetics on the dielectric and electrical properties of BiFeO_(3) films

BiFeO_(3)thin films were prepared using the chemical solution route on Pt/TiO_(2)/SiO_(2)/Si(100)substrates under different crystallization kinetics.The crystallization kinetic effects on the dielectric and electrical properties have been investigated.These properties included dielectric permittivity,electric modulus,electrical conductivity measurements as a function of the temperature(300-525 K)and frequency(10^(2)-10^(6)Hz),and leakage current measurements electric field range±30 kV/cm at room temperature.The differences observed in conductivity and current density of the BiFeO_(3)films were discussed in terms of possible defects induced by the crystallization kinetic.An anomalous relaxor-like dielectric behavior characterized by a broad maximum in the real dielectric permittivity as a function of temperature and the low-frequency dielectric dispersion has been observed.The nonexpected peaks in the real permittivity were accompanied by increasing at least four orders in the conductivity’s magnitude at high temperatures.The origin of the relaxor-like dielectric anomalies is discussed,suggesting that the dielectric permittivity peaks are artifacts due to carrier migration correlated to the onset of the Maxwell-Wagner effect.

Exploring the electromechanical response and electric field-induced dielectric anomalies in PMN-PT electroceramics

Electromechanical and dielectric properties of PMN-PT ferroelectric ceramics are investigated.In particular,dielectric response studies focus on the investigation of the influence of the DC applied electric field on the dielectric permittivity as a function of temperature and frequency.Results reveal an electric field driven dielectric anomaly in the dielectric permittivity curves,e(E),which in turn prevails in the whole ferroelectric phase region and continuously vanishes for temperatures near the paraelectric-ferroelectric phase transition temperature.A schematic model for the domains dynamics of the studied material is proposed taking into account the simultaneous contribution of both 90°and 180°domains walls.