Determination of standard entropy of formation of Al 11Nd 3 by heat capacity measurement from near absolute zero Kelvin

Abstract

The thermodynamic properties of Al 11Nd 3 were investigated by measuring the heat capacities, C p , from near absolute zero (2 K) to 300 K by the relaxation method. In the low temperature range of 2–15 K, three λ-type thermal anomalies were found. The third law entropy of Al 11Nd 3(Al 0.786Nd 0.214) at 298 K was obtained by the integration of polynomials for measured C p . The result was as follows: S 298 ( A l 0.786 N d 0.214 ) ( J K − 1 mo l − 1 ) = − 35.12 ± 0.35. Using this value, the entropy of mixing and the standard entropy of formation at 298 K were obtained as follows: Δ mix S 298 ( A l 0.786 N d 0.214 ) ( J K − 1 mo l − 1 ) = − 2.32 ± 0.39 , Δ f S 298 ° ( A l 11 N d 3 ) ( J K − 1 mo l − 1 ) = − 32.5 ± 5.5.