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DIELECTRIC CONSTANT AND LOSS MEASUREMENTS ON HIGH-TEMPERATURE MATERIALS. Technical Report 182

Technical Report ·
OSTI ID:4140106
Measurement techniques for the frequency range 10/sup 2/ to about 2.5 x 10/sup 10/ are discussed for temperatures to 1650 deg C. These include the use of bridges, resonant circuits, standing-wave methods, and resonant cavities. Data on crystals of Al/sub 2/O/sub 3/, Cr/sub 2/O/sub 3/, MgO, LaAlO/sub 3/, Y/sub 2/O/ sub 3/; on multicrystalline bodies of Al/sub 2/O/sub 3/, BeO, MgO, Mg/sub 2/SlO/ sub 4/, Ta/sub 2/O/sub 5/, T hO; on glass ceramics, silica glass, and BN are presented over smaller temperature and frequency ranges. Pyrolitic BN has a low loss tangent (0.0004 at 1375 deg C, 4.8 x 10/sup 9/cps) and a low temperature coefficient of dielectric constant. Some aluminas and silicas exhibit loss tangents of ca. 0.0006 at 1000 deg C in the microwave region. Microwave losses are due partly to the charge transfer responsible for lowfrequency conductivity and to the vibration spectra of infrared absorption. Both losses are increased by the addition of impurities. (auth)
Research Organization:
Massachusetts Inst. of Tech., Cambridge. Lab. for Insulation Research
NSA Number:
NSA-18-007214
OSTI ID:
4140106
Report Number(s):
NP-13431
Country of Publication:
United States
Language:
English