| Summary: | 碩士 === 國立中正大學 === 物理所 === 96 === As revealed in the power X-ray diffraction and crystallographic data, the partial substitution of Y with (La1-XYX)NiC2 could be systematic up to the solubility limit near x=0.35. The variation of room temperature lattice parameters, a, b, c and V of these substitutional intermetallic samples are consistent with one would expect from a chemical pressure effect. Magnetic, electrical or heat capacity measurements indicate the change in Tc with x is similar to the change in the lattice parameter and the Tc decrease rate is dTc/dx=-6.98 K. According to the BCS theory, the stiffening of the lattice under pressure may change both the electron-phonon coupling strength V0 and the electron density of state at the Fermi level, N(Ef), leading to the decrease of Tc value in the (La1-XYX)NiC2 system.
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