No abstract

Pairs of 99.999%-pure platinum wires were irradiated with equal doses below 10°K and annealed simultaneously. The recovery spectrum of both wires was closely identical. However, when one of the wires was quenched prior to the irradiation, the irradiation-damage recovery was remarkeably different from that of the unquenched wire: The ratio of the rate of recovery of the quenched to the unquenched wire was nearly 1 from 10 to 24°K, near 2 from 24 to 27°K, and near 0 from 28 to 32°K. The amount of recovery of the quenched sample was enhanced 7% over the unquenched sample. These results are strong evidence for long-range (uncorrelated) migration of an interstitial near 28 °K. Only a few percent recovery takes place in either the quenched or the unquenched sample between 35 and 300°K. These observations, combined with other relevant experimental results and calculations based on chemical rate theory, provide evidence that the defects remaining above 35 °K are mainly trapped interstitials, di-interstitials, and vacancies. Stage III is due to the release of trapped interstitials and the migration (or dissociation) of dimers. The vacancies migrate near 600 °K (stage IV).

The electrical resistivity increase per unit electron flux (damage rate) of 99.999%-pure 0.0002-in.-thick platinum foils was measured as a function of incident electron energy from 1.3 to 2.1 MeV near 9°K. Reasonable agreement between the theoretical displacement cross section, calculated with a unit displacement probability, and experimental data is achieved with an effective threshold displacement energy of 36 eVand a Frenkel resistivity of 6X10 -4 ti cm per unit fractional concentration] Frenkel pairs. The ratio of the damage rate of platinum to that of gold is nearly independent of the electron energy for 45 eV

t a c k a t K1 open. As the vent fully opens, the power to the motor is interrupted by a cam-switch arrangement at the motor. However, K1 and K2 remain energized as they are supplied by the voltage leading to the cam-switch circuitry. When the door is closed, this voltage is also removed and K1 is de-energized. The 110 VAC contacts close at K1 and remain closed at K2 because of the charge on C1; thus, K3 is energized. The pair of contacts at K3, paralleling the manually operated start switches, are closed for a time period determined by C1 (approximately 1 second), and a new cycle is initiated.Switch S1 in the circuit allows selection of the automatic repetitive temperature programming, or, when in the manual position, disconnects K3 so that programming is restricted to one cycle only.

Publication costs assisted by the North American Rockwell Corp.The electrochemical behavior of the Ti(III) |Ti(IV) couple was investigated in methanol solutions containing 0.02-0.22 M chloride ion and 0.02-7.0 M water. The presence of two electrochemically distinct Ti(III) complexes was observed and the mechanism of the electrode processes was shown to consist of the reactions e-+ Ti(IV) ^Ti(IH)(a) (E1/2 ~-0.4 V); Ti(III)(a) + H20 ^Ti(III)(b) + C1"(K); Ti(III)(b)T i(IV) + e~( E1/2 ~0.1 V). The equilibrium constant K was evaluated from pulse polarographic and cyclic voltammetric data to be 0.029 ± 0.006. The reaction rates have been calculated from the kinetic contribution to the kinetic polarographic current, and the parameters ks and a of the first electron transfer reaction were estimated from pulse polarographic data. Combining these results with electron spin resonance measurements, the species Ti(III)(a) comprised [TiCl2(CH3OH)4]+ and [TiCl(CH3OH)5]2+. These two species equilibrate rapidly on an electrochemical time scale. Ti(III)(b) was assigned the structure [TiCl(CH3OH)4H20]2+. In addition, the Ti(IV) in methanol containing more than 0.3 M H20 contains at least one more water ligand than the Ti(III), based on the negative shift of the half-wave potential with the concentration of water.