Effects of Irradiation on the Thermal Conductivity of Synthetic Sapphire

Abstract

The thermal conductivity between 2° and 100°K has been measured on synthetic sapphire single crystals and on sintered alumina, before and after reactor and γ-ray irradiations. Reactor irradiation appears to introduce two types of thermal resistivity-producing defects, one of which is dominant at low temperatures. The only effect of γ irradiation is an extra thermal resistivity at low temperatures which saturates for quite small doses. This saturation value seems to depend on the initial perfection of the crystal and is increased by reactor produced damage. At present, detailed information about the defects cannot be derived from thermal conductivity measurements alone.

Thermal conductivity of germanium crystals with different isotopic compositions

“…5 we believe that our data in this region are less reliable than those taken in Moscow.͔ The maximum of (T) amounts to 10.5 kW/mK near 16.5 K for 70 Ge͑99.99%͒, which is the highest value of measured for Ge, higher than the thermal conductivity maximum of sapphire ͑6 kW/mK near 35 K͒ and comparable to that of silver ͑11 kW/mK near 8 K͒. Comparable or higher conductivities have been reported for isotopically enriched diamond, 22,23 sapphire, 67 LiF, 36,43 and also for NaF. 68 The isotopically most disordered sample shows, as expected, the lowest thermal conductivity measured for undoped germanium ͑0.75 kW/mK near 14.5 K͒.…”

Cryogenic Properties of Inorganic Insulation Materials for ITER Magnets: A Review

“…Data from Borodai and Suzdal'tsev [1975] .........10 Berman [1952], Berman et al [1960], Alterovitz et al [1975], Nemoto et al [1985], and citations therein] Data from Burk [1962] and Touloukian et al [1977;citations therein] Data from Wachtman et al [1962] and Touloukian et al [1977;citations therein] Data from Gmelin [1967;1969] (sintered) and Barron et al [1959] Burk [1962] and Touloukian et al [1977;citations therein] Breaking strength of annealed soda-lime glass rods vs. temperature for three periods of load application.…”

Hypersonic Absorption in Quartz at Temperatures Below 30°K

“…Before the interaction the energy of these fast thermal waves will be distributed equally Replacing AN according to (7) by A/co0, we find (dW/dt) = (9/4:)NkTy 2 uS 2 , which is now independent of the collision time 0. The ultrasonic absorption coefficient, which is defined (with W=acoustic energy flux=p^0 3 <5' 2 ) as…”