We have measured the heat capacity of liquid 3 He in silver sinter at pressures from 0 MPa up to 3.31 MPa and in the temperature range from about 1 up to 28 mK. The heat capacity in the normal fluid is found to be the sum of the heat capacity of bulk normal fluid and a temperature-independent heat capacity ⌬C due to amorphous solid layers on the silver sinter surface, where ⌬Cϭ7.3Ϯ6.8 J K Ϫ1 m Ϫ2 corresponds to 1Ϯ1 amorphous solid layers. This value is in rough agreement with other results, including solid 3 He and 3 He adsorbed on Vycor and silver sinter, and differs from the value for liquid 3 He in silver sinter reported by Schrenk and König. Our result indicates that the amorphous solid layers on a large surface area yield a universal ⌬C in unit area throughout liquid, solid, and adsorbed 3 He in contact with a large surface. The superfluid transition temperature of the liquid 3 He in the silver sinter is in good agreement with the theory of Kjäldman and Kurkijärvi when taking the pore diameter to be 3400 Å, and our observations differ from the results of Schrenk and König.
We have observed an excess specific heat in bcc solid 3 He at low temperatures and at pressures between the melting pressure and 46 bar. The excess specific heat is nearly independent of temperature. In the solid just above the melting pressure, the magnitude of the anomaly is about 2.5 times larger than that at high pressures. Except for the solid near the melting pressure, the magnitude is constant with pressure and is nearly the same as that in liquid 3 He in Vycor. This anomaly of the specific heat in solid 3 He is explained in terms of the amorphous surface solid on a disordered substrate.
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