Universality Of The Dynamic Process Of Thermal Expansion And Its Appearance In High-Tc Superconductors

In this paper, the dynamic proceess of thermal expansion and its appearance in high-Tc superconductors and some other materials are studied. It includes three parts: study of the universality of dynamic process of thermal expansion, study of the dynamic process of thermal expansion of high-Tc superconductors near Tc and study of the dynamic length change of Nd-glass cylinder under the excitation of Xe light. The macroscopic mechanism and microscopic mechanism of dynamic process of thermal expansion are discussed. Besides, an automatic measurement of low-temperature specific heat and a measurement of thermal diffusivity of thin film was established and some samples were measured.In the experimental study of the universality of dynamic process of thermal expansion, a 0.1μs CO₂ laser pulse with wavelength 10.6μm and pulse power 1J/cm² is used as heating pulse. Using the direct observing method, the dynamic thermal expansion processes of Al, Ni, Cu, Ni-Cr-Mn-Si alloy, amorphous films and paper are observed. The rear-surface temperature rise history of some samples have been detected by (Hg,Cd)Te infrared radiation pyrometer. The universality of dynamic process of thermal expansion has been verified in the experiment.The dynamic process of thermal expansion has the following characteristics:...