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Articles you may be interested inEvidence for field enhanced electron capture by EL2 centers in semiinsulating GaAs and the effect on GaAs radiation detectors A. S. EPSTEIN with the rate of cooling in the above region. Silver selenide powders 14 were compacted using 0.05 g/addition and a pressure of 70000 Ib/in. 2 • The disks were heated at a rate of ",3 deg/min and sintered at 200°C for 15 min. Sample temperatures were monitored using an Land N recorder which recorded the voltages of the thermocouples inserted in the sample. The samples were cooled at various rates. It was noted that the most important region to control in the cooling curve in order to directly influence the figure of merit was where (3 phase grain growth occurred, i.e., the temperature 14 The silver/selenium ratio was > 2.0 and between 2.0 and 2.28. Different batches of silver selenide may have slightly differen t ratios. range mentioned above. The results of our investigation are shown in Fig. 5. The abscissa in Fig. 5 is actually plotted in terms of the time to cool from the supercooled phase transition temperature (117°C) to 93°C. This is the cooling in the (32 phase and is the region of (32 phase grain growth. It is noted from Fig. 5 that a maximum in figure of merit appears to occur around 7 min. Extremely slow or fast cooling rates give figures of merit at room temperature of "'2XlO~3 per degree. ACKNOWLEDGMENT

Work Performed Under Contract No. NAS-7-100-954328 Battelle Columbus Laboratories Cofumbus, Ohio U.S. Department of Energy Solar Enery-DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government.

An experimental Peltier refrigerator utilizing thermoelements of annular configuration has been designed, constructed, and operated. The thermoelectric materials used are p- and n-type Bi2Te3 with ρp=2×10−3 ohm-cm, ep=180 μvolts/°C, ρn=8.5×10−4 ohm-cm, and en=−150 μvolts/°C. The device has been operated under ``no-load'' conditions over a range of power inputs and has exhibited a maximum ΔT of 49°C. A simple theory relating to the performance of Peltier thermocouples is derived. Experimental performance of the device is shown to agree with theoretical predictions within experimental error.

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