Low Temperature Specific Heat of Ni(NO3)2.6H2O; Antiferromagnetic Interactions.
CARNEGIE-MELLON UNIV PITTSBURGH PA DEPT OF PHYSICS
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Measurements of the specific heat of nickel nitrate hexahydrate for 0.5 T 12K reveal a Schottky anomaly with Cp max1.373 calmole-K at Tmax2.35K. The experimental data are explained by the complete splitting of the S1 ground state triplet, with levels separated successively by 4.80K and 3.26K. The lattice contribution is found to be 4.11 x 10 to the -4th power x T cubed calmole-K. The discrepancies between the level spacings as deduced from these measurements and from the reported powder susceptibility data are removed by taking into account a small antiferromagnetic exchange interaction Ak 0.6K in a molecular field approximation. The total magnetic entropy change is found to be within 0.6 of the theoretically predicted value for a spin 1 system. Author
- Solid State Physics