Classical Physics

   

Empirical Reassessments of Lattice Defect Properties in High-Purity Gold

Authors: Raymond John Sonoff

Analyses of extensive sets of quenched-in resistance data obtained over wide ranges in elevated temperature, quench rate, and isothermal annealing time for multiple specimens have led to establishment of the following determinations: 1. Confirmation of the reliability of a graphical back extrapolation technique(B.E.T.) for ascertaining no-loss equilibrium vacancy concentrations over the temperature range from 400oC through 925oC. 2. In general, for straight downquench treatments involving quench temperatures ranging from 750oC to 925oC and/or moderate to large sink density specimens, diffusion-limited models appear to be required to describe the annealing kinetics, whereas chemical rate equation models appear to be required when low sink density specimens and/or quench temperatures ranging from 400oC to 700oCare involved wherein losses are found to be proportional to an effective time-of-quench parameter. 3. Estimates for the vacancy formation energy and vacancy formation entropy over the temperature range from 400oC to 925oC. 4. An estimate for the heat of solution of helium in pure gold ascertained over the temperature range from 400oC to 550oC. 5. Graphically-represented insights that reveal the nature of isothermal annealing kinetics for many of the elevated temperature Q&A series treatments to be essentially diffusion-limited, exhibiting losses that generally reflect tA2/3 or tA1/2 dependencies during the decay period down to at least 1/e of the fraction remaining of Normalized Quenched-In Resistance. 6. Evidence that metastable residual resistance (MRR) levels result when elevated temperature Q&A series treatments involving TQ ≥ 700oC, TA ≤ 500oC, and isothermal annealing times beyond one hour are performed. 7. Determinations of parameters, such as vacancy defect chemical potential, effective vacancy migration energies, mean relaxation times, instantaneous vacancy activation energies, and absolute macroscopic sink efficiency. 8. Graphically-represented insights regarding the influence of vacancy defect chemical potential upon a) absolute macroscopic sink efficiency, and b) values for instantaneous vacancy activation energies, especially as annealing temperatures approached the associated quench temperature. 9. Insight as to the nature, density, and associated vacancy concentration of secondary defects considered responsible for metastable residual resistance levels was accomplished via Transmission Electron Microscopy (TEM) observations of two gold ribbon foils previously subjected to Q&A's involving TQ at 800oC and 900oC, respectively, followed by contiguous, prolonged anneals for one hour at 385oC and 340oC, respectively, and subsequent preparation for TEM methods. 10. An estimate for sink structure recovery activation energy at 950oC was obtained from analyses of monitored straight downquench ΔRQN(also referred to NQIR) magnitudes associated with quenches from 800oC performed on specimens that had been initially subjected to direct deformation followed by a series of several extended HTA treatments at 950oC each lasting for a number of hours and followed by an 800oC straight downquench to assess what changes occurred in NQIR values. Extensive sets of data involving five-mil diameter pure 99.9999 weight percent(6N) pure gold wires maintained in situ during subjection to thermal treatments and subsequent lattice defect electrical resistance determinations at liquid helium temperatures have been analyzed. As a consequence of these studies, quantitative estimates for numerous lattice defect parameters were made possible, and insights into the interrelationships among many of these parameters were revealed. From analyses of data associated with various sets of elevated temperature treatments that were performed, quantitative determinations for each of the following parameters were achieved: 1. Melting Point Resistance Ratio for Gold 2. Establishment of a temperature-time profile defined as a Long-Term Anneal(LTA) treatment to asymptotically approach "vacancy-free" residual resistance levels for potentiometric resistance measurements conducted at 4.2oK. 3. "No Loss" Normalized Quenched-In Resistance NQIR(T) Ξ QIR(T)/R(40oC) 4. "No Loss" Vacancy resistivity∆ρV(T) 5. "No Loss" equilibrium vacancy concentration CV(T) 6. Vacancy formation energy (EFV) 7. Vacancy formation entropy (SFV) 8. Heat of solution of helium in pure gold 9. Effective vacancy migration energy EMV(eff) 10. Remaining Vacancy Supersaturation Ratios VSR(TQ, TA, tA) defined as ≡ [Cv(TQ,TA, tA) - Cv(TA, tA)]/Cv(TA, tA → ∞) 11. Vacancy defect chemical potential μv(TQ, TA, tA) 12. Absolute macroscopic sink efficiency € 13. Variations in time exponent (m) during NQIR(TQ, TA, tA) Q&A series treatments 14. Metastable Residual Resistance (MRR) Levels for Q&A series treatments 15. Initial annealing rates (IARs) defined as{[NQIR(TQ, TA, tA= 0) - NQIR(TQ, TA, ΔtA(initial))] / (ΔtA(initial)) }, wherein ΔtA(initial)is the duration time of the shortest isothermal anneal (hence the added descriptor initial)for the overall NQIR(TQ, TA, ΔtA) series treatment. 16. Mean relaxation times tme and defined as NQIR(TQ, TA, tA= 0) / {[NQIR(TQ, TA, tA= 0) - NQIR(TQ, TA, (ΔtA(initial))] / (ΔtA(initial))} 17. Instantaneous Vacancy Activation energy EMV(act) 18. Post-direct deformation sink structure recovery activation energy

Comments: 537 Pages.

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[v1] 2020-06-18 18:19:16

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