The Sintering Effect of Magnetic Entropy Change on ${\rm Ba}_{2}{\rm FeMoO}_{6}$

Abstract

The magnetocaloric effect and magnetization behavior have been analyzed in the double-perovskite Ba <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> FeMoO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> compound with the sintering temperature at 1273, 1373, and 1473 K. Samples were fabricated by conventional solid-state reaction method. X-ray diffraction measurements revealed that all the samples are single phase in cubic structure. Detailed investigations of the influence of sintering on magnetic entropy behavior of the sample exhibited the variation of <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TC</i> . The magnetic entropy changes, Δ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SM</i> of about 0.98 ~ 1.93 J/kg K were obtained in the temperature range of 320-330 K for the Ba <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> FeMoO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> compound. The values of Δ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SM</i> are increased two times with increasing sintering temperature from 1273 to 1473 K. The enhancement of the magnetic entropy change is believed to be due to changes in the microstructure of the samples. It seems to favor the increase of magnetic order, which changes magnetic part of the entropy of a solid around the magnetic ordering temperature.