Hideyuki Kimura

Band structure, magnetic, and transport properties of two dimensional compounds Sr2−xGdxCoO4

The layered perovskite compound Sr2−xGdxCoO4 has not yet been subjected to detailed study so far. In this report, structures, transport, magnetic properties, and first principle calculations will be reported for the two dimensional compounds Sr2−xGdxCoO4 (xu2009=u20090.5, 0.75, 1, 1.25). Rietveld refinement revealed that these compounds are crystallized in K2NiF4-type structures with space group I4/mmm. It was found that the lattice parameter c decreases as x increases. Through the Curies Weiss fitting of the temperature dependent magnetization, it was found that the Sr1.25Gd0.75CoO4 sample exhibits a weak ferromagnetic to paramagnetic transition at about 62u2009K, with a Curie constant of 0.113u2009emu K/mol. Band structure calculations indicated that electrons of these compounds are spin polarized at the Fermi level. The 2-D Variable Range Hopping model fitting indicated that the two dimensional variable range hopping mechanism could be used to account for the conducting mechanism for these samples.

Measurement of Thermal Deformation Utilizing Holographic Interferometry (1st Report). Development of Measurement Apparatus for Thermal Deformation Utilizing Compensation Method of Interferometric Fringes by Correcting Stand.

This paper describes a development of an apparatus for highly accurate measurement of a thermal deformation of a mechanical part. The apparatus makes possible a real time monitoring a microscopic change of the thermal deformation pattern by using real-time holographic interferometry. One of the most important problems to be solved on a measurement of thermal deformation is how to fix a measuring object. When environmental temperature changes, the spurious interferometric fringes are happened by an unnecessary slip between contact surfaces of the measuring object and its holder, due to thermal expansion differences between them. An adjustable correcting stand utilizing piezoelectric elements is developed for a real time compensation of the spurious fringes. The effectiveness of the correcting stand for a precise and real time measurement of the thermal deformation pattern was confirmed experimentally. An air bath that has an optically stable window for observation of the deformation from outside is used for highly accurate control of the temperature of the measuring object. The interferometric fringes are recorded on a thermoplastic plate for real time monitoring of the changing process of the thermal deformation pattern.