High-resolution, high-sensitive ac calorimeter.

Abstract

A high-resoln., high-sensitivity, automated ac calorimeter capable of heat capacity measurements of very small samples (m < 20 mg) with a temp. resoln. of a few mK in the ac mode is described. This calorimeter also can be operated in the relaxation mode to provide abs. heat capacity values with precision and accuracy of around 2%. This calorimeter was tested by measuring the heat capacity of gadolinium over its ferromagnetic phase transition. The results agree well with the literature data giving, however, substantially better resoln. of the heat capacity in the crit. region.