| Summary: | 碩士 === 國立東華大學 === 應用物理研究所 === 98 === This thesis consists of three parts. The first part we present the calibration of the thermal expansion coefficient and dielectric constant measuring system in the temperature range between 6 K and 330 K. The second part we report the investigations of specific heat (CP) and thermal expansion coefficient (α) on the heavy fermion compound CeRu2Al10 to study the mysterious phase transition at 27 K. The final part, we study the dielectric properties for the rutile-based oxides with chemical formula FeTiM1O6 (M1 = Ta, V, Nb, Zr).
Near the phase transition, pronounced anomalous features in these thermodynamic properties are noticed for CeRu2Al10. Analyses of the specific heat data clearly reveal that the phase transition is essentially second-order with the opening of an energy gap of about 100 K over a portion of Fermi surface. Further, by applying the Ehrenfest relation, a rather large increase of T0 under hydrostatic pressure for CeRu2Al10 is obtained, being consistent with the experimental results.
The dielectric constant measurements reveal that the substitution of transition metals with different valence on the M1 site causes a substantial change in the electronic configuration, which in turn significantly alters the dielectric properties for these rutiles. Besides, it is found that the dielectric constant of FeTiM1O6 (M1 = Nb, Zr) increases as the ionic radius increases.
Finally, all experiment results consistently show that the calibration of thermal expansion coefficient and dielectric constant measuring system
VI
have been completed and functional.
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