Published

2017-01-01

RESISTIVIDAD ELÉCTRICA Y COEFICIENTE SEEBECK EN COMPUESTOS DEL TIPO Ca(La)MnO PREPARADOS POR EL MÉTODO DE REACCIÓN DE ESTADO SÓLIDO

ELECTRICAL RESISTIVITY AND SEEBECK COEFFICIENT IN Ca(La)MnO COMPOUNDS PREPARED BY SOLID STATE REACTION METHOD

Keywords:

Materiales termoeléctricos, compuestos CaLaMnO, propiedades de transporte. (es)
Termoelectric materials, CaLaMnO compounds, transport properties. (en)

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Authors

  • Jorge I. Villa Grupo de Materiales Termoeléctricos, Departamento de Física, Universidad Nacional de Colombia, Bogotá, Colombia.
  • Julio E. Rodríguez Grupo de Materiales Termoeléctricos, Departamento de Física, Universidad Nacional de Colombia, Bogotá, Colombia.
Utilizando el método de reacción de estado sólido se prepararon muestras policristalinas del compuesto Ca1-xLaxMnO3 (0 ≤ x ≥ 0.15). Sus propiedades de transporte se estudiaron en función de la temperatura y el contenido de lantano, a partir de mediciones de resistividad eléctrica ro(T) y coeficiente Seebeck S(T) en el rango de temperatura entre 100 y 290K. Las propiedades estructurales y morfológicas se estudiaron mediante estudios de difracción de rayos-X (XRD) y microscopia electrónica de barrido (SEM), respectivamente. El coeficiente Seebeck es negativo en todo el rango de temperatura estudiado, indicando una conducción dada por portadores de carga negativos, su magnitud disminuye con el contenido de lantano desde |-261| mV/K hasta |-120| mV/K. La resistividad eléctrica muestra un comportamiento de carácter semiconductor, descrito mediante un mecanismo tipo hopping de pequeños polarones. Las propiedades termoeléctricas de los compuestos obtenidos se evaluaron a través de su factor de potencia termoeléctrico PF, el cual alcanza valores máximos cercanos a 2mW/K2cm, estos valores permiten considerar esta familia de compuestos como posibles materiales útiles en aplicaciones termoeléctricas.

By using the solid state reaction method samples of  Ca1-xLaxMnO3 (0 ≤ x ≥ 0.15) were prepared. Their transport properties were studied by electrical resistivity rho(T) and Seebeck coefficient S(T) measurements as a function of temperature and lanthanum content, in the temperature range between 100 and 290K. The structural and morphological properties were studied by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM), respectively. The Seebeck coefficient is negative throughout the studied temperature range indicating a conduction given by negative charge carriers, its magnitude decreases with the lanthanum content from |-261| mV/K to |-120| mV/K. The electrical resistivity shows a semiconducting behavior, it was interpreted in terms of small polaron hopping model. Thermoelectric properties of the obtained compounds were studied by the thermoelectric power factor PF, which reaches maximum values around 2mW/K2cm, these values become this kind of ceramics promising thermoelectric compound, to be used in technological applications.

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