Heat capacity near first order phase transitions and the magnetocaloric effect:: An analysis of the errors, and a case study of Gd5(Si2Ge2) and Dy

The heat capacity measured in an adiabatic heat pulse calorimeter with nonzero heat capacity suffers from intrinsic errors in the vicinity of a first order phase transition. When these errors are carried over into the calculation of the magnetocaloric effect, the latter also suffers from large systematic errors. The sources of the intrinsic errors in the heat capacity near the first order phase transition temperature and the procedures to minimize them are discussed. The experimental heat capacity data of Gd-5(Si2Ge2) and ultra pure Dy, both of which exhibit first order phase transition, are used to confirm the theoretical conclusions. (C) 1999 American Institute of Physics. [S0021-8979(99)06323-9].