Direct measurement of the magnetocaloric effect in La0.67Ca0.33MnO3

Polycrystalline perovskite La0.67Ca0.33MnO3 was synthesized by a sol-gel method. Its adiabatic temperature change Delta T-ad induced by a magnetic field change was measured directly. At 268 K, near its Curie temperature T-C, Delta T-ad of La0.67Ca0.33MnO3 induced by a magnetic field change of 2.02 T reaches 2.4 K. The latent heat Q and magnetic entropy change -Delta S-M induced by a magnetic field change were calculated from the temperature dependence of Delta T-ad and zero-field heat capacity C-p. The maximum values of Q and -Delta S-M in La0.67Ca0.33MnO3 induced by a magnetic field change of 2.02 T are 1.85 J g(-1) and 6.9 J kg(-1) K-1, respectively. The former is larger than the phase transition latent heat of heating or cooling, which is about 1.70 J g(-1). (c) 2005 Elsevier B.V. All rights reserved.