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Influence of the Calcination Temperature on the Optical and Mechanical Properties of Y2O3-MgO Nanocomposite

Yong S.-M., Choi D. H., Lee K., Ko S.-Y., Cheong D.-I.

Archives of Metallurgy and Materials

2018

Vol. 63, iss. 3

1481--1484

Y2O3-MgO nanocomposites are one of the most promising materials for hypersonic infrared windows and domes due to their excellent optical transmittance and mechanical properties. In this study, influence of the calcination temperature of Y2O3-MgO nanopowders on the microstructure, IR transmittance, and hardness of Y2O3-MgO nanocomposites was investigated. It was found that the calcination temperature is related to the presence of residual intergranular pores and grain size after spark plasma sintering. The nanopowders calcined at 1000°C exhibits the highest infrared transmittance (82.3% at 5.3 μm) and hardness (9.99 GPa). These findings indicated that initial particle size and distribution of the nanopowders are important factors determining the optical and mechanical performances of Y2O3-MgO nanocomposites.

Effects of an external magnetic field on the perpendicular magnetic anisotropy of electrodeposited micro-patterned arrays

Jeung W. Y., Choi D. H., Lee K. H.

Materials Science

2003

Vol. 21, No. 1

147-154

We have investigated effects of an external magnetic field on PMA (perpendicular magnetic anisotropy) for electrodeposited continuous films and micro-patterned arrays. For continuous films, external magnetic field gave rise to a highly aligned grain structure with a PMA. Our results indicated that the effect of applied magnetic field is apparent only under specific current density. XRD patterns showed that electrodeposited continuous Co films consist of hexagonal cobalt only and have strong texture for grains with c-axis lying perpendicular to the film plane. The patterned arrays were fabricated by UV-LIGA process, and PMA was modified by changing the aspect ratio of patterned arrays. Our results suggest that there is a critical aspect ratio at which PMA dominates in-plane anisotropy. For the patterned arrays, however, an external magnetic field was little effective due to large concentration polarization.