ANNEALING OF REACTOR RADIATION DAMAGE IN LEAD AND BISMUTH TELLURIDES
Reactor irradiations of specimens of n-type and p-type lead and bismuth tellurides were carried out to neutron doses of 5 x 10/sup 19/ fast (E > 1 Mev) neutrons/cm/sup 2/ and 6 x 10/sup 20/ thermal neutrons/cm/sup 2/ at an irradiation temperature of 60 plus or minus 20 deg C. Comparison of pre- and postirradiation electrical properties of duplicate specimens irradiated with and without cadmium shields indicated that, for these exposures, the principal damage is caused by fast neutrons. This confirmed earlier results obtained from similar specimens irradiated to fast and thermal neutron doses one-quarter as great. Comparison of the results of the two experiments indicated that damage caused by fast neutrons tends to saturate at a dose of 1 to 2 x 10/sup 19/ fast neutrons/cm/ sup 2/. Hall coefficient data indicated that the major portion of damage to electrical and thermal conductivity and Seebeck coefficient of n-type PbTe could be attributed to depression of electrical carrier concentration. This is tentatively attributed to a bombardment-induced trapping level 0.037 volts below the bottom of the conduction band. Annealing experiments performed with the irradiated n-type PbTe indicated complete recovery of measured properties for the cadmiumshielded specimen at temperatures in the range of 140 to 200 deg C. Small unannealable changes tn electrical properties of the unshielded specimen were, within experimental and calculational uncertainties, attributable to increases in carrier concentration caused by transmutation-induced increases in iodine doping level. Similar results were obtained in the case of n-type Bi/sub 2/Te/sub 3/. Damage to p-type PbTe was not completely removed by annealing. Cold-work experiments carried out on this brittle material indicated that the unannealed damage may be caused by effects associated wtth the encapsulation procedures. The largest changes in electrical properties before annealing were observed in the case of the initially undoped p-type Bi/sub 2/Te/sub 3/, in which Seebeck and Hall coefficients showed a reversal in sign as a result of the irradiation. (auth)
- Research Organization:
- Knolls Atomic Power Lab., Schenectady, N.Y.
- DOE Contract Number:
- W-31-109-ENG-52
- NSA Number:
- NSA-16-012178
- OSTI ID:
- 4806171
- Report Number(s):
- KAPL-2159
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-62
- Country of Publication:
- United States
- Language:
- English
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THE EFFECTS OF REACTOR IRRADIATION ON THE THERMOELECTRIC PROPERTIES OF LEAD AND BISMUTH TELLURIDES
ANNEALING OF NEUTRON RADIATION DAMAGE IN p-TYPE PbTe
Related Subjects
ANNEALING
BISMUTH COMPOUNDS
CADMIUM
CARRIERS
COLD WORKING
DEFECTS
ELECTRIC CONDUCTIVITY
ENERGY LEVELS
FAST NEUTRONS
HALL EFFECT
IMPURITIES
IODINE
IRRADIATION
LEAD COMPOUNDS
NEUTRON BEAMS
QUANTITY RATIO
RADIATION DOSES
RADIATION EFFECTS
SAMPLING
SATURATION
SEEBECK EFFECT
SEMICONDUCTORS
SHIELDING
TELLURIDES
TEMPERATURE
THERMAL CONDUCTIVITY
THERMAL NEUTRONS
THERMOELECTRICITY
TRAPS