Síntesis del Material Cerámico Monofásico Bi0,7La0,3Fe0,9Ti0,1O3,05 y Estudio de su Conductividad Eléctrica

Moyano, María1; Lascano, Luis1

1Escuela Politécnica Nacional, Departamento de Física, Quito, Ecuador

Resumen: Uno de los materiales ferroicos interesante por sus potenciales aplicaciones es la ferrita de bismuto, BiFeO3, pero su síntesis como fase pura estable y su conductividad eléctrica relativamente alta, son dos problemas aún por superar. El objetivo del presente trabajo fue dopar a la ferrita de bismuto con lantano y titanio de manera tal de sintetizar el compuesto monofásico y reducir dicha conductividad con respecto a la ferrita de bismuto no dopada. Para ello, se sintetizó material cerámico de composición Bi0,7La0,3Fe0,9Ti0,1O3,05. La síntesis se realizó mediante el método convencional de reacción en estado sólido. La obtención del compuesto monofásico tuvo lugar a la temperatura de calcinación de 950°C. Mediante espectroscopía de impedancia compleja se determinaron valores de conductividad eléctrica del material en función de la temperatura, así como la energía de activación correspondiente. La conductividad ocurre mediante difusión de iones y sigue la ley de Arrhenius, con una variación del valor de la energía de activación en torno a los 300°C, que sería a su vez la temperatura de Néel del compuesto. La conductividad eléctrica del material dopado es menor que aquella de la ferrita de bismuto para temperaturas entre 180 y 500°C, y la extrapolación a temperatura ambiente proporciona una conductividad del orden de 10-14 S/cm. transmisión.

Palabras clave: multiferroico, ferrita de bismuto, conductividad, Néel.

Synthesis of Single-Phase Ceramic Material Bi0,7La0,3Fe0,9Ti0,1O3,05 and Study of Electrical Conductivity

Abstract: One interesting ferroic material is bismuth ferrite, BiFeO3, due to its potential applications. However, the synthesis of an stable pure phase material and its relatively high conductivity, are still two problems to overcome. The aim of this work was to synthesize a single phase bismuth ferrite material doped with lanthanum and titanium to reduce the conductivity compared to the undoped bismuth ferrite. Thus, a ceramic material of the composition Bi0,7La0,3Fe0,9Ti0,1O3,05was synthesized by a conventional solid state reaction with a calcination temperature of 950 °C. The electrical conductivity as a function of temperature of the obtained phase pure material as well as the corresponding activation energy were determined by complex impedance spectroscopy. The conductivity occurs by diffusion of ions and follows the Arrhenius law, with a variation of the activation energy at around 300 °C, which is at the same time the Néel temperature of the compound. The electrical conductivity of the doped material is lower than that of undoped bismuth ferrite at temperatures between 180 and 500 °C, and the extrapolation to room temperature provides a conductivity in the order of 1-14 S/cm.

Keywords: multiferroic, bismuth ferrite, conductivity, Néel.

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