Low-Temperature Thermal Conductivity of Irradiated and Swept Synthetic Quartz.

Scope of Study. This study was concerned with the measurement of the thermal conductivities of three different synthetic quartz samples. Thermal conductivity measurements were taken for two samples, Electronic grade sample, EG-S, and Premium Q sample, PQ-S, on the range of 4.5 to 140K. Premium Q sample, PQ-E11 was run over the 1.6 to 48K range of temperature. Two sample holder systems were used. The effects of radiation damage at room temperature and of electrolyzing in the presence of hydrogen were studied. Findings and Conclusions. The shape of the thermal conductivity versus temperature curves were characteristic for single crystal insulating materials. Irradiation of samples EG-S and PQ-S at room temperature did not cause significant differences with the thermal conductivity of as-received samples. For sample PQ-E11 a dip centered near 5K was introduced into its thermal conductivity after it was irradiated at room temperature. This result suggested a resonant phonon scattering caused by either the Al-OH or the {Al(,e+)}('0) centers. In order to determine whether the resonant scattering was caused by the Al-OH centers or by the {Al(,e+)}('0) centers, sample PQ-E11 was electrolyzed in hydrogen, this sweeping removed the alkalis and replaced them with hydrogen to form Al -OH centers. The {Al(,e+)}('0) centers were also removed by the process. The sweeping process significantly increased the thermal conductivity maximum. The dip in the thermal conductivity versus temperature curve near 5K was still present. Thus, the Al-OH center is the most likely cause of the resonant scattering.