Spectral control of thermal radiation emitted from rectangular microcavities (0.5x0.5x0.5μm³) was investigated through emission experiment at a high temperature. The microcavities were fabricated on a mirror-like finished Ni metal surface. Through measurement of normal spectral emittance, the maximum emittance was obtained at a wavelength around 0.86-0.88μm which was very close to that (0.894μm) estimated from the cavity resonance theory. The emittance reached the maximum value of 0.95 and then decreased drastically with respect to wavelength from the cut-off wavelength. On longer wavelength range from 1.7μm, it was equal to the emittance from mirror-like finished surface.

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Thermal properties of sintered SiC polycrystal and single crystal at micrometer-scale were quantitatively measured by using a thermal microscope with thermo-reflectance and periodic heating techniques. The average value of thermal effusivity of the polycrystal was almost equal to that measured by laser flash technique. While the thermal effusivity of the single crystal was homogeneous, that of the polycrystal was heterogeneous. The portions of very low thermal effusivity were found to correspond to pores present. The thermal effusivities from the region excepting the pore portions in the sintered SiC were in the range of 21.0 to 25.8 kJ·s^-0.5m^-2K^-1and the variation of the thermal effusivity was estimated about 5 kJ·s^-0.5m^-2K^-1.

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