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Specific Heat of Ni(NH 3 ) 2 Ni(CN) 4 ·2C 6 H 6 at Low Temperature

1971; Physical Society of Japan; Volume: 30; Issue: 4 Linguagem: Inglês

10.1143/jpsj.30.1054

1347-4073

Shoichi Nagata, Tsuyoshi Maruyamauchi, Takashi Watanabe,

Advanced Chemical Physics Studies

The hear capacity C p of powdered specimen of Ni(NH 3 ) 2 ·Ni(CN) 4 ·2C 6 H 6 has been measured between 1.3 and 10°K. A sharp λ-shaped anomaly for antiferromagnetic phase change has been found at 2.39±0.01°K. The total entropy change which was measured is 15.91 ( J /mol°K), but total magnetic ordering entropy is Rln (2 S +1)=9.13 ( J /mol°K) with S =1 for ground state of nickel ion. The excess entropy is assumed to be due to the hindered rotations of NH 3 group. The low temperature asymptotic form for the heat capacity is C p ∝1/ T 2 e - Δ / T , where the amount of magnetic elementary excitation energy Δ is 8.85°K.