In this study, a ZnS film of 8-mm thickness was prepared on graphite using a hot-wall-type CVD technique. The ZnS thick film was then hot isostatically pressed under different pressures (125–205 MPa) in an argon atmosphere. The effects of pressure were systematically studied in terms of crystallographic orientation, grain size, density, and transmittance during the HIP process. X-ray diffraction pattern analysis revealed that the preferred (111) orientation was well developed after a pressure of 80 MPa was applied during the HIP process. A high transmittance of 61.8% in HIPZnS was obtained under the optimal conditions (1010oC, 205MPa, 6 h) as compared with a range of approximately 10% for the CVD-ZnS thick film under a 550-nm wavelength. In addition, the main cause of the improvement in transmittance was determined to be the disappearance of the scattering factor due to grain growth and the increase in density.

We develop a purification process of Hg2Br2 raw powders using a physical vapor transport(PVT) process, which is essential for the fabrication of a high performance acousto-optic tunable filter(AOTF) module. Specifically, we characterize and compare three Hg2Br2 powders: Hg2Br2 raw powder, Hg2Br2 powder purified under pumping conditions, and Hg2Br2 powder purified under vacuum sealing. Before and after purification, we characterize the powder samples through X-ray diffraction and X-ray photoelectron spectroscopy. The corresponding results indicate that physical properties of the Hg2Br2 compound are not damaged even after the purification process. The impurities and concentration in the purified Hg2Br2 powder are evaluated by inductively coupled plasma-mass spectroscopy. Notably, compared to the sample purified under pumping conditions, the purification process under vacuum sealing results in a higher purity Hg2Br2 (99.999 %). In addition, when the second vacuum sealing purification process is performed, the remaining impurities are almost removed, giving rise to Hg2Br2 with ultra-high purity. This high purification process might be possible due to independent control of impurities and Hg2Br2 materials under the optimized vacuum sealing. Preparation of such a highly purified Hg2Br2 materials will pave a promising way toward a high-quality Hg2Br2 single crystal and then high performance AOTF modules.

MCFC 작동온도인 650˚C에서 음극의 creep과 소결에 의한 구조적 변형을 막기 위해 기계적 합금법에 의한 Ni-WC분말을 합금화하여 변형에 대한 저항성을 증대시키고자 하였다. 80시간동안 어트리션 밀링을 실시한 분말은 XRD 분석결과 결정규칙이 파괴된 비정질 상을 보였다. 제조된 분말은 적당한 점도의 슬러리로 제조후 테이프 캐스팅법에 의해 green sheet를 제조하였다. 제조된 박판의 두께는 0.9mm였고, 평균 기공 크기는 3~5μm, 기공율은 55%였다. 소결체의 XRD 분석결과 2차성은 생성되지 않았으며, SEM 및 dot-Mapping image를 통해 Ni matrix 안에 W 입자가 미세하고 균일하게 분포되어 있어 고용강화 및 분산강화를 통해 Ni 음극의 기계적 특성을 향상시킬 것으로 기대된다.

MCFC(Molten Carbonate Fuel Cell) 작동온도인 650˚C에서 Ni 음극의 Creep 및 소결에 대한 저항성을 개선시키고자 Ni-W(WC) 복합재료를 기계적 합금법으로 제조하였다. 기계적 합금화한 분말의 XRD분석결과 밀링시간이 증가함에 따라 재료의 규칙적인 결정이 파괴되어 비정질화 되어가는 경향을 보였다. 소결은 1280˚C의 수소분위기에서 10시간 행하였다 소결된 시편의 dot-mapping 및 TEM 분석결과 Ni-W 계면에서의 2차상 관찰되지 않았으나 0.1μm 이하의 W이 Ni 기지내에 미세하고 균일하게 분포되어 있는 것으로 나타났다. 이와같이 미세하고 균일하게 분포되어 있는 W은 고용강화 및 분산강화 효과를 통하여 Ni음극의 기계적 특성을 향상시킬 것으로 기대된다.