Low-temperature specific-heat data C(T) of two Na0.35CoO2. 1.3H2O samples (I and II) with temperature T down to 0.6 K without and with magnetic field of 8 T are presented. The normal-state linear coefficient of specific heat γn, Debye temperature ΘD, superconducting transition temperature Tc, specific heat jump at Tc, ΔC/γnsTc, and superconducting volume of fraction (SVF) are 14.89 mJ/mol K2, 503, 4.7 K, 1.96, and 26.6% for sample I and 13.94 mJ/mol K2, 362, 4.5 K, 1.45, and 47.4% for sample II, respectively. Because the superconducting properties may depend on the water content of sample, it is found that the better quality (higher SVF) of sample, the nodal order parameter is better than BCS isotropic s-wave model in describing the gap function of this interesting compound Na0.35CoO2. 1.3H2O.
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