Effect of high temperature sintering on the structural and the magnetic properties of La1.4Ca1.6Mn2O7

We investigate the effect of sintering temperature on the structural and magnetic properties of La1.4Ca1.6Mn2O7 double perovskite manganite compound prepared by the sol-gel route. Three sintering temperatures (1273, 1473 and 1673 K) are utilized for the heat treatment. Regardless of the sintering temperature, the tetragonal crystal structure with the I4/mmm space group is stable. However, a reduction in a and an increase in c lattice parameters along with a significant increase in crystallite-size occur on increasing the sintering temperature. This is also accompanied by the growth of grains. Grain-growth and changing crystallite-sizes account for the changes in magnetization, Curie temperature and magnetic entropy-change values. As the sintering temperature increases from 1273 to 1673 K the Curie temperature increases from 225 to 268 K and the magnetic entropy-change increases from 0.58 to 3.1 J kg(-1) K-1 respectively. (C) 2010 Elsevier B.V. All rights reserved.