The persistence of the magnetocaloric effect in (La1-x)A(x)(0.67)Ba0.33Mn1.05O3-δ

Polycrystalline samples of (La1-xAx)0.67Ba0.33Mn1.05O3-δ, with A being a mixture of lanthanides containing 66% La, 22% Nd, 8% Pr and 4% Ce, were prepared by the glycine-nitrate method, with target compositions of x = 0, 0.33, 0.67 and 1. The effect of the mixture of lanthanides on the Curie temperature, TC, and the magnetocaloric properties was investigated.

The prepared samples are single phase, with space group R-3c. The lattice parameters and average A-site ionic radius, rA decrease linearly with x while the size disorder, as characterized by the variance, σ2, increases from 0.014 to 0.017 with x. As x is increased, the increase in σ2 drives a linear decrease in TC.

The magnetic entropy change, ΔSM, for a field change of 1 T is obtained by magnetization measurements, giving a maximum value of 1.7 J/kg K, and a relative cooling power, RCP, of 43 J/kg, independent of x. These results suggest that replacing lanthanum with a mixture of lanthanides is a realistic way to tune the working temperature of magnetocaloric manganites while maintaining a constant magnetocaloric effect.