Development of ferromagnetic spinels for optical isolation at 10. 6. mu. m
Vacuum hot pressing was used to fabricate CdCr/sub 2/S/sub 4/, CdCr/sub 2/Se/sub 4/ and (1-x) CdCr/sub 2/S/sub 4/.x CdCr/sub 2/Se/sub 4/ discs with diameters of 1.25 cm from fine powders and small single crystals to relative densities as high as 99.6%. Optical attenuation coefficients of approx. 1.0 cm/sup -1/ at 10.6 m were obtained for CdCr/sub 2/S/sub 4/, and values of 12.1 cm/sup -1/ and 14.9 cm/sup -1/ for the selenide and sulfur-selenide mixture. Two-and-three-phonon absorption bands were found to limit the transmission of CdCr/sub 2/S/sub 4/ at lambda > 10 ..mu..m. Extrinsic absorption mechanisms caused the higher attenuation coefficients in CdCr/sub 2/Se/sub 4/ and the mixture. The main extrinsic mechanisms at long wavelengths were free carrier absorption (in CdCr/sub 2/Se/sub 4/) and an impurity absorption band at 16.3 ..mu..m due to Cr/sub 2/O/sub 3/. At short wavelengths the attenuation coefficient was dominated by scattering from pores and second phases. Free carrier absorption was found to be induced by free selenium present in the starting powders. Suppression of this absorption was achieved by optimizing the hot-pressing procedure in order to remove free selenium. The presence of pores was attributed to incomplete densification arising from the presence of second phases (CdSe and Cr/sub 2/Se/sub 3/) and the absence of plastic deformation as a densification mechanism. Laser damage thresholds of 250 MWcm/sup -2/ and 100 MWcm/sup -2/ were measured at 10.6 ..mu..m for CdCr/sub 2/S/sub 4/ and CdCr/sub 2/Se/sub 4/, respectively.
- Research Organization:
- Rochester Univ., NY (USA). Inst. of Optics
- DOE Contract Number:
- AS02-76DP40050
- OSTI ID:
- 5224947
- Report Number(s):
- DOE/DP/40050-9
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
360601* -- Other Materials-- Preparation & Manufacture
360603 -- Materials-- Properties
CADMIUM COMPOUNDS
CADMIUM SELENIDES
CADMIUM SULFIDES
CHALCOGENIDES
CHROMIUM COMPOUNDS
CHROMIUM SELENIDES
CHROMIUM SULFIDES
DENSITY
FABRICATION
HOT PRESSING
INORGANIC PHOSPHORS
MATERIALS
MATERIALS WORKING
OPTICAL PROPERTIES
PHOSPHORS
PHYSICAL PROPERTIES
PRESSING
SELENIDES
SELENIUM COMPOUNDS
SEMICONDUCTOR MATERIALS
SULFIDES
SULFUR COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
360601* -- Other Materials-- Preparation & Manufacture
360603 -- Materials-- Properties
CADMIUM COMPOUNDS
CADMIUM SELENIDES
CADMIUM SULFIDES
CHALCOGENIDES
CHROMIUM COMPOUNDS
CHROMIUM SELENIDES
CHROMIUM SULFIDES
DENSITY
FABRICATION
HOT PRESSING
INORGANIC PHOSPHORS
MATERIALS
MATERIALS WORKING
OPTICAL PROPERTIES
PHOSPHORS
PHYSICAL PROPERTIES
PRESSING
SELENIDES
SELENIUM COMPOUNDS
SEMICONDUCTOR MATERIALS
SULFIDES
SULFUR COMPOUNDS
TRANSITION ELEMENT COMPOUNDS