An Isothermal Peltier Cell Calorimeter For Measuring the Magnetocaloric Effect

We have developed a method for isothermal calorimetry for the determination of the entropy change in magnetic materials. Heat absorbed and released by the sample at constant temperature is measured by means of Peltier cells, used in an active way to simultaneously measure the heat current and keep constant the sample temperature. In the paper we describe the method, the Peltier cell calibration and the test apparatus. The results obtained on a Gadolinium sample at room temperature under a magnetic field up to 0.9 T are discussed. The comparison with other methods demonstrates the validity of the proposed approach to fulfil the isothermal conditions (DeltaTles5 mK) and to obtain a faster time response