QUARTZ CRYSTAL AGING EFFECTS.

An investigation was made to reduce the aging and increase the reliability of quartz resonators. Average aging rates of 81.9 to 500 kHz units at 85C ranged from 0.15 to 0.28 ppmwk for a period of 4500 hours subsequent to an initial aging phase of 60 days. Units having lolished edges performed less well than others having a state-of-the-art edge finish. The average aging of 123 3 MHz resonators at 85C was 1.7 pp10 to the 9th powerwk during 4500 hours. Aluminum plated units mounted in evacuated HC-27U holders averaged 0.72 pp10 to the 9th powerwk versus 1.5 pp10 to the 9th powerwk for gold plated ones. The average Q values were 1.2 and 0.75 x 10 to the 6th power respectively. Annular-field excitation of plano-convex 5 MHz units reduced aging rates to 110 that of conventionally-plated control units and the Q was doubled. Frequency spectra suffered no degradation. X-ray topography indicated oscillation was confined to the central 316 in. diameter zone for plano-convex units but extended over the entire plane-parallel zone 0.340 in. diameter of units with beveled edges. The annulus was external to the active zone in the case of the plano-convex units and their Q values were four times greater. Aging of 10 MHz resonators at 125C indicated container dependency rates for units in T-5 12 holder were greater than for those in HC-27U. Serious outgassing or higher initial pressures in the T-5 12 holder are indicated. Author